%0 journal article %@ 0935-9648 %A Blagojevic, N.,Das, S.,Xie, J.,Dreyer, O.,Radjabian, M.,Held, M.,Abetz, V.,Müller, M. %D 2024 %J Advanced Materials %N %P 2404560 %R doi:10.1002/adma.202404560 %T Toward Predicting the Formation of Integral-Asymmetric; Isoporous Diblock Copolymer Membranes %U https://doi.org/10.1002/adma.202404560 %X The self-assembly and nonsolvent-induced phase separation (SNIPS) process of block copolymers and solvents enables the fabrication of integral-asymmetric, isoporous membranes. An isoporous top layer is formed by evaporation-induced self-assembly (EISA) and imparts selectivity for ultrafiltration of functional macromolecules or water purification. This selective layer is supported by a macroporous bottom structure that is formed by nonsolvent-induced phase separation (NIPS) providing mechanical stability. Thereby the permeability/selectivity tradeoff is optimized. The SNIPS fabrication involves various physical phenomena—e.g., evaporation, self-assembly, macrophase separation, vitrification – and multiple structural, thermodynamic, kinetic, and process parameters. Optimizing membrane properties and rationally designing fabrication processes is a challenge which particle simulation can significantly contribute to. Using large-scale particle simulations, it is observed that 1) a small incompatibility between matrix-forming block of the copolymer and nonsolvent, 2) a glassy arrest that occurs at a smaller polymer concentration, or 3) a higher dynamical contrast between polymer and solvent results in a finer, spongy substructure, whereas the opposite parameter choice gives rise to larger macropores with an elongated shape. These observations are confirmed by comparison to experiments on polystyrene (PS)-block-poly(4-vinylpyridine) (P4VP) diblock copolymer membranes, varying the chemical nature of the coagulant or the temperature of coagulation bath. %0 journal article %@ 0033-4545 %A Abetz, V. %D 2024 %J Pure and Applied Chemistry %N 2 %P 259-281 %R doi:10.1515/pac-2023-1130 %T Flexible polymer networks: rubber elasticity and segmental orientation %U https://doi.org/10.1515/pac-2023-1130 2 %X Thermoreversible networks are very attractive materials because of a large variety of suitable thermoreversible chemical bonds which can be used for crosslinking. In future, to certain extent, they may replace so far used irreversibly crosslinked networks and contribute to more sustainable material concepts also in the field of crosslinked elastomers. This paper gives some theoretical basis for understanding the elastic deformation properties of crosslinked polymers and presents some experimental tools for studying deformation behavior not only on a macroscopic length scale but also on a segmental scale. Basic knowledge of these two topics is useful for chemists and material scientists when designing new sustainable elastomeric polymer networks. %0 journal article %@ 1438-7492 %A Klein, F.C.,Vogt, M.,Abetz, V. %D 2024 %J Macromolecular Materials and Engineering %N 3 %P 2300187 %R doi:10.1002/mame.202300187 %T Reprocessable Vanillin-based Schiff Base Vitrimers: Tuning Mechanical and Thermomechanical Properties by Network Design %U https://doi.org/10.1002/mame.202300187 3 %X Bio-based polymer building blocks derived from abundant biomass represent a promising class of monomers for the synthesis of sustainable high-performance polymers. Lignin-derived vanillin is used as a bio-based, aromatic molecular platform for chemical modifications. The use of vanillin aldehyde derivatives as monomers with different alkyl chain length, cured with bio-based and less-toxic di- and triamines, leads to covalent adaptable Schiff base networks and thus enables sustainable and thermally reprocessable high-performance materials without using highly toxic amines. A process is presented to prepare homogeneous films of crosslinked materials that are thermally reprocessable while maintaining their mechanical performance. The network structures, mechanical properties, and thermal stability of the obtained polymeric sheets are characterized in detail. By systematically adjusting the composition of the network building blocks, the mechanical properties could be varied from tough materials with a high elastic modulus of 1.6 GPa to materials with high flexibility and elastomeric behavior with an elongation at break of 400%. Furthermore, the stress–relaxation behavior of stoichiometric and nonstoichiometric Schiff base vitrimers is investigated. The combination of bio-based building blocks and the degradability of Schiff base networks under acidic conditions resulted in sustainable, environmentally friendly, chemically and thermomechanically recyclable vitrimers with self-healing and shape-memory properties. %0 journal article %@ 1873-2976 %A Kerner, M.,Wolff, T.,Brinkmann, T. %D 2024 %J Bioresource Technology %N Part A %P 129917 %R doi:10.1016/j.biortech.2023.129917 %T Efficient supply with carbon dioxide from flue gas during large scale production of microalgae: A novel approach for bioenergy facades %U https://doi.org/10.1016/j.biortech.2023.129917 Part A %X The efficiency of using enriched CO2 from flue gas for large scale production of the green microalgae Chlorella sorokiniana in a bioenergy facade was studied. Using a membrane device, the enrichment of CO2 from heating system flue gas in the low pressure product gas was up to 49 vol% and the CO2 recovery was 62 %. With a static mixer the re-compressed product gas was applied to the culture medium with mean losses during cultivation of only 24 %. Thereby the pH could be maintained at a mean of 6.2 and a temperature always below 28 °C, both optimal for growth of Chlorella sorokiniana. Although PAR solar radiation during midday always exceeded 1000 µmol m−2 s−1 mean photosynthetic efficiency was 0.54 g mol−1. Results indicate that the chosen approach for CO2 supply overcomes the problem of CO2 losses and allows for a more economic and sustainable microalgae production in a bioenergy facade. %0 journal article %@ 2214-7144 %A Usman, M.,Glass, S.,Mantel, T.,Filiz, V.,Ernst, M. %D 2024 %J Journal of Water Process Engineering %N %P 104733 %R doi:10.1016/j.jwpe.2023.104733 %T Electro-sorption and -desorption characteristics of electrically conductive polyacrylonitrile membranes to remove aqueous natural organic matter in dead-end ultrafiltration system %U https://doi.org/10.1016/j.jwpe.2023.104733 %X Electrically conductive (EC) membranes have emerged as an innovative approach in removing natural organic matter (NOM) by electro-sorption (e-sorption) when external anodic potential (AP) is applied. In this study, the EC membranes were established by a forming a porous nanolayer of Pt nanoparticles via magnetron sputtering on both sides of virgin and chemically modified PAN ultrafiltration (UF) membranes. The modified PAN membranes were functionalized with ethylenediamine (PAN-EDA) and sodium hydroxide (PAN-NaOH). The virgin PAN membrane material contains nitrile group and demonstrated a negative zeta potential in the analyzed pH range. The PAN-EDA membrane owned amidine and amine groups, whereas PAN-NaOH membrane possessed carboxyl and amide groups in the membrane matrix. The PAN-NaOH and PAN-EDA membranes exhibited isoelectric points at 3.7 and 7.8, respectively. Electrical field-assisted UF experiments were conducted with Suwannee River NOM in dead-end mode and NOM removal was monitored using different methods of NOM characterization (e.g., SEC, DOC and UV254 absorbance). The results revealed that the non-electrically conductive (NEC) and EC virgin PAN membranes exhibited almost no intrinsic adsorption (at 0 V external potential) and e-sorption of NOM at 2.5 V AP respectively. However, NEC PAN-NaOH and PAN-EDA membranes showed DOC intrinsic sorption loadings of 17 mg·m−2 and 258 mg·m−2 at permeate flux 100 L·m−2·h−1 and pH 7 respectively. In comparison, the DOC e-sorption loadings of the EC PAN-NaOH and EC PAN-EDA membranes at 2.5 V AP were 197 mg·m−2 and 525 mg·m−2 under same test conditions respectively. The NOM e-desorption characteristics of the EC modified PAN membranes were also investigated to regenerate membranes for a sustainable filtration process. The results indicated that the EC PAN-NaOH and PAN-EDA membranes can be regenerated by reversing the electrical polarity almost completely. In conclusions, the outcomes of this work confirm that the presence of the derivatives of amines (e.g., amines, amidine and amide groups) and carboxyl group are necessary in the membrane matrix to induce e-sorption and -desorption characteristics. %0 journal article %@ 0376-7388 %A Zhang, Z.,Rahman, M.,Ternes, I.,Bajer, B.,Abetz, V. %D 2024 %J Journal of Membrane Science %N %P 122270 %R doi:10.1016/j.memsci.2023.122270 %T Engineering Soft Nanochannels in Isoporous Block Copolymer Nanofiltration Membranes for Ion Separation %U https://doi.org/10.1016/j.memsci.2023.122270 %X Membranes with high ion selectivity are important for the separation of ionic species at the Ångstrom scale. Here, we report on positively charged isoporous block copolymer (BCP) nanofiltration membranes with designed soft nanochannels. The isoporous BCP membranes were obtained from the combination of BCP self-assembly and non-solvent-induced phase separation. The well-defined soft nanochannels were engineered via a versatile post-modification approach using a combination of di- and monofunctional alkyl halide. The water permeance and effective pore size of the membranes were fine-tuned within the nanofiltration regime. Both single- and binary-salt retentions demonstrate the capability of separating mono-/divalent cations based on the ionic size difference in Ångstrom scale, charge, and energy to strip away the hydration shells. Especially the real selectivity from the binary-salt systems is > 2 times higher than the selectivity obtained from the single-salt systems, e.g., the real selectivity of K+/Mg2+ is up to 15 for the 10 mM binary-salt mixture with a mole ratio of 1:1. Such enhancement arises from the competition effect regarding energy barrier, size of hydrated ion, and diffusivity. The Na+/Mg2+ binary-salt system with simulating the salt concentration ratio of the seawater illustrates the potential of the resulting membranes to recover the valuable ionic species from water, e.g. Mg, classified as a “critical raw material” in Europe. The Na+/Mg2+ real selectivity is up to 42 with a permeance of 15 L m−2 h−1 MPa−1 at a salt concentration of 10 mM. %0 journal article %@ 0376-7388 %A Ramirez Kantun, M.A.,Weigelt, F.,Neumann, S.,Shishatskiy, S.,Brinkmann, T. %D 2024 %J Journal of Membrane Science %N %P 122519 %R doi:10.1016/j.memsci.2024.122519 %T Temperature stable, polymeric thin-film composite membrane for hydrogen separation %U https://doi.org/10.1016/j.memsci.2024.122519 %X The high temperatures and aggressive chemical conditions of many relevant industrial processes such as the hydrogen production from hydrocarbon fuel sources restrict the use of polymeric membranes for gas separations (GS) that could make such processes more efficient and environmentally friendlier whilst reducing their operational costs. Therefore, this work was centered on the development of a thin-film composite membrane (TFCM) prepared with high-performance polymeric materials capable of withstanding temperatures above 200 °C in industrial GS applications and which could eventually be integrated to perform in situ separations in a reactor. An innovative prototypical three-layered TFCM featuring the polyimide 6FDA-6FpDA as selective layer deposited on a cross-linked (CL) Matrimid® 5218 (Matrimid) porous support prepared on a thermally stable polyphenylene sulfide (PPS) nonwoven was investigated in two different gas permeation experimental facilities in a range from 30 to 200 °C and feed pressures of up to 10 bar. The TFCM exhibited low permeances compensated by outstanding ideal selectivities for H2/CO2, H2/CH4 and O2/N2 gas pairs. This behavior was attributed to the formation of an interpenetrating network between 6FDA-6FpDA and Matrimid, caused by a swelling effect of the solvent used to form the selective layer on the surface of the cross-linked Matrimid porous membrane. A drop in membrane performance was observed above 170 °C due to a reduction in the thermal stability of the CL Matrimid resulting from the opening of the imide rings of the polyimide backbone during the cross-linking reaction. %0 journal article %@ 2637-403X %A Brennecke, F.,Clodt, J.,Brinkmann, T.,Abetz, V. %D 2024 %J Journal of Advanced Manufacturing and Processing %N 2 %P e10175 %R doi:10.1002/amp2.10175 %T Numerical and experimental investigation of the unexpected thickening effect during PolyActive™ coating of TFC membranes %U https://doi.org/10.1002/amp2.10175 2 %X In this work, we used a previously described computational fluid dynamics (CFD) model of a roll-to-roll coating process for the fabrication of thin-film composite membranes to predict the final coating thickness for PolyActive™, a commercially available multiblock copolymer utilized for CO2 removal membranes. We found a strong thickening effect that could not be explained by our previous model. We investigated the process experimentally. In addition, we conducted a variety of simulations with extensions of the initial CFD model. Based on our findings, we conclude that the Marangoni effect, that is, gradients of surface tension that induce secondary flow patterns in the meniscus region, is the most likely source of the observed thickening. We explain the simulation results in order to understand the physical mechanisms at play and to show how especially surface tension gradients that arise from the particular flow structure in the meniscus may explain the additional transfer of polymer solution to the membrane. Finally, we draw some conclusions on future research and give ideas on future improvements of the process. To our knowledge, Marangoni effects for the coating of PolyActive™ were not described so far in the literature, even though it is a well-known polymer for gas separation membranes targeted at CO2 removal. Roll-to-roll coating is a well-established coating method and often believed to be suitable for the scale-up of membrane production, therefore we think that this work will help membrane researchers who are using similar coating devices to be cautious about possible complications in the process. %0 journal article %@ 2077-0375 %A Schuldt, K.,Lillepärg, J.,Pohlmann, J.,Brinkmann, T.,Shishatskiy, S. %D 2024 %J Membranes %N 3 %P 66 %R doi:10.3390/membranes14030066 %T Permeance of Condensable Gases in Rubbery Polymer Membranes at High Pressure %U https://doi.org/10.3390/membranes14030066 3 %X The gas transport properties of thin film composite membranes (TFCMs) with selective layers of PolyActive™, polydimethylsiloxane (PDMS), and polyoctylmethylsiloxane (POMS) were investigated over a range of temperatures (10–34 °C; temperature increments of 2 °C) and pressures (1–65 bar abs; 38 pressure increments). The variation in the feed pressure of condensable gases CO2 and C2H6 enabled the observation of peaks of permeance in dependence on the feed pressure and temperature. For PDMS and POMS, the permeance peak was reproduced at the same feed gas activity as when the feed temperature was changed. PolyActive™ TFCM showed a more complex behaviour, most probably due to a higher CO2 affinity towards the poly(ethylene glycol) domains of this block copolymer. A significant decrease in the permeate temperature associated with the Joule–Thomson effect was observed for all TFCMs. The stepwise permeance drop was observed at a feed gas activity of p/po ≥ 1, clearly indicating that a penetrant transfer through the selective layer occurs only according to the conditions on the feed side of the membrane. The permeate side gas temperature has no influence on the state of the selective layer or penetrant diffusing through it. The most likely cause of the observed TFCM behaviour is capillary condensation of the penetrant in the swollen selective layer material, which can be provoked by the clustering of penetrant molecules. %0 journal article %@ 0024-9297 %A Hub, L.,Koll, J.,Held, M.,Radjabian, M.,Abetz, V. %D 2024 %J Macromolecules %N 5 %P 2273-2286 %R doi:10.1021/acs.macromol.3c02256 %T Amphiphilic block copolymers via blue-light-induced iniferter RAFT ab initio emulsion polymerization in water-alcoholic media %U https://doi.org/10.1021/acs.macromol.3c02256 5 %X Amphiphilic block copolymers comprise a fascinating class of smart materials due to their unique ability to self-organize, making them attractive candidates for a wide range of applications in materials engineering and medical sciences. The synthesis of these copolymers commonly involves harmful solvents, especially in classical living anionic polymerization. With the development of reversible addition–fragmentation chain transfer (RAFT) and polymerization–induced self-assembly (PISA), an environmentally more friendly and versatile method has been established for the synthesis of such amphiphilic block copolymers. Through the utilization of visible light to initiate polymerization through the so-called photoiniferter process, we emphasize the adaptability of this photopolymerization in different scales although the incident light illuminates only the surface area of the reaction vessels. We describe an easily adjustable, blue-light-initiated RAFT PISA approach to synthesize a series of amphiphilic poly(N,N-dimethylacrylamide)–block–polystyrene (PDMA–b–PS) and poly(4-vinylpyridine)–block–polystyrene (P4VP–b–PS) diblock copolymers with low molecular weight dispersities. The polymerizations were conducted as both two-step and semibatch processes. Furthermore, the effect of scalability on the polymerization kinetics was investigated, proving the light-induced RAFT polymerization as a scalable polymerization method in a batch process with a reaction volume of up to 500 mL. The bulk morphology of both resulting diblock copolymers having different weight fractions of the minor and major blocks was analyzed. While a cylindrical PDMA microdomain in a PS matrix can be observed at 20–25% by weight of PDMA, the equivalent composition reveals a spherical morphology of P4VP domains in a PS matrix. In essence, the scalable, rather eco-friendly photoinduced synthesis of tailored, nanostructured block copolymers without harmful solvents significantly increases their suitability for applications. %0 journal article %@ 1944-8244 %A Glaß, S.,Schmidt, M.,Merten, P.,Abdul Latif, A.,Fischer, K.,Schulze, A.,Friederich, P.,Filiz, V. %D 2024 %J ACS Applied Materials and Interfaces %N 16 %P 20990-21000 %R doi:10.1021/acsami.3c18805 %T Design of Modified Polymer Membranes Using Machine Learning %U https://doi.org/10.1021/acsami.3c18805 16 %X Surface modification is an attractive strategy to adjust the properties of polymer membranes. Unfortunately, predictive structure–processing–property relationships between the modification strategies and membrane performance are often unknown. One possibility to tackle this challenge is the application of data-driven methods such as machine learning. In this study, we applied machine learning methods to data sets containing the performance parameters of modified membranes. The resulting machine learning models were used to predict performance parameters, such as the pure water permeability and the zeta potential of membranes modified with new substances. The predictions had low prediction errors, which allowed us to generalize them to similar membrane modifications and processing conditions. Additionally, machine learning methods were able to identify the impact of substance properties and process parameters on the resulting membrane properties. Our results demonstrate that small data sets, as they are common in materials science, can be used as training data for predictive machine learning models. Therefore, machine learning shows great potential as a tool to expedite the development of high-performance membranes while reducing the time and costs associated with the development process at the same time. %0 journal article %@ 2470-1343 %A Aliyev, E.,Emmler, T.,Lillepaerg, J.,Shishatskiy, S.,Dizge, N.,Filiz, V. %D 2024 %J ACS Omega %N 13 %P 15282–15293 %R doi:10.1021/acsomega.3c09042 %T Two-dimensional nanoporous crosslinked polymer networks as emerging candidates for gas adsorption %U https://doi.org/10.1021/acsomega.3c09042 13 %X This paper illustrates the gas adsorption properties of newly synthesized nanoporous cross-linked polymer networks (CPNs). All synthesized CPNs possess N-rich functional groups and are used for the utilization of carbon dioxide and methane. Good gas adsorption and selectivities are obtained for all of the samples. Among the materials, HEREON2 outperforms better selectivity for methane separation from nitrogen rather than zeolites, activated carbons, molecular sieves, covalent organic frameworks, and metal–organic frameworks (MOFs). The accessibility of the N-rich functionalities makes these materials potential candidates for the separation of hydrocarbons via increased polarizabilities. High-pressure adsorption experiments showed that the synthesized two-dimensional nanoporous materials also have a high affinity toward carbon dioxide. HEREON2 powders showed an increased experimental CO2/N2 selectivity of ∼25,000 at 50 bar due to the presence of nitrogen groups in the structure. Fourier-transform infrared spectroscopy (FTIR), solid-state NMR, X-ray diffraction, thermogravimetric analysis, energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were applied for the characterization of the synthesized nanoporous CPNs. The results show a potential new pathway for future CPN membrane development. %0 journal article %@ 0032-3861 %A Safari, M.,Ocando, C.,Liao, Y.,Drechsler, M.,Volk, N.,Schaller, R.,Held, M.,Abetz, V.,Schmalz, H.,Müller, A.J. %D 2024 %J Polymer %N %P 126863 %R doi:10.1016/j.polymer.2024.126863 %T Morphology and Confinement Effects on Crystallization Kinetics in Polyethylene Containing Block Copolymers %U https://doi.org/10.1016/j.polymer.2024.126863 %X This paper investigates the morphology and crystallization kinetics of polyethylene (PE) containing block copolymers, differing in block number (di- vs. triblock copolymers) and composition (ABA triblock co- vs. ABC triblock terpolymers). In these block copolymers, the crystallizable PE block is linked to amorphous poly(methyl methacrylate) (PMMA) and/or polystyrene (PS) blocks, and for one triblock terpolymer, poly(ethylene oxide) (PEO) was introduced as an additional crystallizable block. The topological confinement exerted by the covalent linkage of PE to the other blocks (glassy PMMA and PS, PEO) in combination with the morphological confinement into different PE microdomains (cylinders, lamella) significantly influence the crystallization behavior, resulting in slower crystallization kinetics compared to pure PE. The strongest effects were observed for triblock terpolymers, where the lamellar PE domains are disrupted by PS cylinders or distorted PS domains. This research enhances our understanding of block copolymers with confined crystallizable segments, aiding in tailored material design. %0 journal article %@ 2041-1723 %A Zhang, Z.,Gao, L.,Boes, A.,Bajer, B.,Stotz, J.,Apitius, L.,Jakob, F.,Schneider, E.S.,Sperling, E.,Held, M.,Emmler, T.,Schwaneberg, U.,Abetz, V. %D 2024 %J Nature Communications %N %P 3308 %R doi:10.1038/s41467-024-47007-y %T An Enzymatic Continuous-Flow Reactor Based on a Pore-size Matching Nano- and Isoporous Block Copolymer Membrane %U https://doi.org/10.1038/s41467-024-47007-y %X Continuous-flow biocatalysis utilizing immobilized enzymes emerged as a sustainable route for chemical synthesis. However, inadequate biocatalytic efficiency from current flow reactors, caused by non-productive enzyme immobilization or enzyme-carrier mismatches in size, hampers its widespread application. Here, we demonstrate a general-applicable and robust approach for the fabrication of a high-performance enzymatic continuous-flow reactor via integrating well-designed scalable isoporous block copolymer (BCP) membranes as carriers with an oriented and productive immobilization employing material binding peptides (MBP). Densely packed uniform enzyme-matched nanochannels of well-designed BCP membranes endow the desired nanoconfined environments towards a productive immobilized phytase. Tuning nanochannel properties can further regulate the complex reaction process and fortify the catalytic performance. The synergistic design of enzyme-matched carriers and efficient enzyme immobilization empowers an excellent catalytic performance with >1 month operational stability, superior productivity, and a high space-time yield (1.05 × 105 g L−1 d−1) via a single-pass continuous-flow process. The obtained performance makes the designed nano- and isoporous block copolymer membrane reactor highly attractive for industrial applications. %0 journal article %@ 2077-0375 %A Kinfu, H.H.,Rahman, M.M.,Schneider, E.S.,Cevallos-Cueva, N.,Abetz, V. %D 2024 %J Membranes %N 6 %P 133 %R doi:10.3390/membranes14060133 %T Using the Assembly Time as a Tool to Control the Surface Morphology and Separation Performance of Membranes With a Tannic Acid–Fe3+ Selective Layer %U https://doi.org/10.3390/membranes14060133 6 %X Thin-film composite (TFC) membranes containing a metal–polyphenol network (MPN)-based selective layer were fabricated on a porous polyacrylonitrile support. The MPN layer was formed through coordination-based self-assembly between plant-based tannic acid (TA) and an Fe3+ ion. For the first time, we demonstrate that TFC membranes containing TA-Fe3+ selective layers can separate small organic solutes in aqueous media from equimolar mixtures of solutes. The effect of the assembly time on the characteristics and performance of the fabricated selective layer was investigated. An increase in the assembly time led to the formation of selective layers with smaller effective pore sizes. The tannic acid–Fe3+ selective layer exhibited a low rejection towards neutral solutes riboflavin and poly(ethylene glycol) while high rejections were observed for anionic dyes of orange II and naphthol green B. Permeation selectivities in the range of 2–27 were achieved between neutral and charged dyes in both single- and mixed-solute experiments, indicating the significant role of Donnan exclusion and the charge-selective nature of the membranes. The rejection efficiency improved with an increasing assembly time. Overall, this study demonstrates that the assembly time is a vital casting parameter for controlling the permeance, rejection and selectivity of thin-film composite membranes with a tannic acid–Fe3+ selective layer. %0 journal article %@ 1614-6840 %A Kim, H.,Deng, M.,Fortuin, A.,Würger, T.,Georgopanos, P.,Kramer, D.,Zheludkevich, M.,Höche, D. %D 2024 %J Advanced Energy Materials %N %P 2401266 %R doi:10.1002/aenm.202401266 %T Influence of Simple Salts on Solvent Reduction Stability at Mg-Alloy Anodes Interface: A Potential-Dependent DFT Study %U https://doi.org/10.1002/aenm.202401266 %X The significance of incorporating anion species into electrolyte solvation structures, particularly with doubly charged Mg2 + ions, is investigated using the grand canonical density functional theory (GC-DFT) approach. In an extension of previously established methodology, the work explores the thermodynamic stability in acetonitrile (AN) at the interface with Mg3Bi2 and Mg2Sn. Two different anions, TFSI− and,ClO4-, are strategically incorporated based on energy comparisons. Despite the known chemical compatibility of alloy anodes with the electrolyte solution, the research reveals a novel form of solvent degradation, which is also reported in the case of pure Mg anode with conventional electrolytes. Notably, the AN molecule adjacent to anion species exhibits reduced susceptibility to reduction (−0.8 – −0.4 V vs Mg2 +/Mg) in the lower potential range in comparison with the solvation structure of full dissociation. Charge density difference and density of states analyses detail solvent molecules becoming electrophilic, with the LUMO overlapping with the Fermi level at lower potentials when the electrostatic interaction with anion species are considered. Experimental studies using nuclear magnetic resonance (NMR) spectroscopy and linear sweep voltammetry (LSV) validate the theoretical results, providing a comprehensive understanding. This methodology, augmenting prior approaches, provides valuable guidance for electrolyte composition based on predominant solvation structures in multivalent solutions. %0 journal article %@ 1434-0860 %A Breitenbach, S.,Skoglund, M.,Lillepaerg, J.,Emmler, T.,Mantwill, F. %D 2024 %J Forschung im Ingenieurwesen - Engineering Research %N %P 32 %R doi:10.1007/s10010-024-00752-4 %T On the influence of sorbents on the static stiffness of Air Springs %U https://doi.org/10.1007/s10010-024-00752-4 %X Air Springs are deployed in many technical areas today. In the premium segment of the automotive industry in particular, they are being used more and more frequently. The load-independent spring rate results in a better ride comfort. Since the stiffness of the Air Spring is significantly influenced by the enclosed air volume, this usually leads to a conflict of objectives between the available installation space and the stiffness optimum. To reduce the spring stiffness while maintaining the same design space, Coackley and Elliot describe in their patent the use of adsorbents such as activated carbon in the enclosed air volume of the spring. By binding air molecules to the adsorbent, more air molecules fit into the enclosed Air Spring volume, while the size and pressure of the Air Spring remain the same. This paper describes how the so-called “virtual volume” is created by adsorption and how it can be determined by simplified measurements using a gas pycnometer. Furthermore, it is shown how these measurements are related to the static stiffness of an Air Spring, so that a prediction of the static stiffness of an Air Spring filled with sorbent, in this case activated carbon, is possible by simple pycnometric measurements. %0 journal article %@ 1616-301X %A Lemich, S.B.,Soltau, S.,Weißpflog, M.,Schulze, V.R.,Feliu, N.,Hankiewicz, B.,Abetz, V. %D 2024 %J Advanced Functional Materials %N %P 2400995 %R doi:10.1002/adfm.202400995 %T Defining New Benchmarks of Low CTAB-Concentration-Based Gold Nanorod Synthesis: The Underestimated Potential of Polymer-Directed Anisotropic Growth %U https://doi.org/10.1002/adfm.202400995 %X This work presents new anisotropic growth-directing copolymers suitable for the seed-mediated growth of gold nanorods (GNRs). Copolymers with different architectures are studied. They all contain dimethylaminomethyl methacrylate (DMAEMA) functionalized with 1-bromohexadecane (BHD) as the vital component. For the synthesis of the different copolymers, the photo-iniferter reversible addition–fragmentation chain transfer (photoRAFT) polymerization is used, where DMAEMA is combined with a lower critical solution temperature (LCST) polymer block for better solubility after the functionalization. The results show that the presented copolymers can induce anisotropic growth of gold nanoparticles. Additionally, the influence of the LCST of the water-soluble block and the temperature of the growth solution on the GNR synthesis are investigated. Furthermore, the plasmonic behavior of the resulting GNRs solution is investigated at temperatures around the LCST of the copolymer. %0 journal article %@ 0376-7388 %A Hub, L.,Koll, J.,Buhr, K.,Radjabian, M.,Abetz, V. %D 2024 %J Journal of Membrane Science %N %P 123021 %R doi:10.1016/j.memsci.2024.123021 %T pH-responsive size- and charge-selective block copolymer membrane for the separation of small proteins %U https://doi.org/10.1016/j.memsci.2024.123021 %X Blue-light-induced RAFT polymerization was utilized to synthesize poly(N,N-dimethylacrylamide)–block–polystyrene (PDMA–b–PS) diblock copolymers to obtain 40 g per batch for membrane fabrication. Using a combination of self-assembly and non-solvent induced phase separation (SNIPS), larger isoporous membranes (≈ 0.5 m · 0.3 m) were fabricated with pore diameters of ≈ 25 nm in the dry state and around 4 nm in the wet state. These membranes were post-modified with hydrochloric acid to impart negatively charged, pH-responsive poly(acrylic acid)–block–polystyrene (PAA–b–PS) membranes. While all proteins like cytochrome C, insulin, lysozyme, myoglobin, and ovalbumin were fully rejected by the pristine PDMA–b–PS membrane, the PAA–b–PS membrane demonstrated selective rejection based on protein size and charge, effectively rejecting the proteins with a hydrodynamic radius Rh ≥ 1.9 nm. The PAA–b–PS membrane showed a real selectivity of 4.1 for the positively charged protein cytochrome C compared to the similarly sized, but negatively charged insulin, as well as a real selectivity of 16.1 towards the negatively charged ovalbumin. This illustrates the size- and charge-selective characteristics of the PAA–b–PS membrane for protein separation. %0 journal article %@ 0032-3861 %A Weerathaworn, S.,Meyer, A.,Abetz, V. %D 2024 %J Polymer %N %P 127311 %R doi:10.1016/j.polymer.2024.127311 %T Vitrimers based on block copolymers with diverse block sequences %U https://doi.org/10.1016/j.polymer.2024.127311 %X Vitrimers based on block copolymers give access to adaptable polymer networks where the resulting properties can be adjusted not only by the vitrimer chemistry itself but also can be influenced by the structure of the block copolymer. In this work, linear AB, ABA, and BAB block copolymers are introduced as backbones in vinylogous urethane vitrimers to produce crosslinked materials that are reprocessable and have a wide range of tunable mechanical properties. The narrow-disperse block copolymers were synthesized by photoiniferter reversible addition-fragmentation chain transfer polymerization (photoRAFT). Two different types of hydrophobic A blocks, poly(methyl methacrylate) and poly(ethyl methacrylate) with a higher glass transition temperature compared to the hydrophilic B block, poly(2-hydroxyethyl methacrylate), were chosen. The B block carries the functional groups for further modification to obtain acetoacetylated side groups, which are then transformed to vinylogous urethane crosslinks. It has been found that the architectures of backbones as well as the alkyl substituents in the side groups of the A block influence the final performance of the vitrimers. By adjusting block sequences, the mechanical properties can be varied from hard to tough to elastic materials corresponding to BAB, ABA, and AB block copolymer vitrimers, respectively. These materials are reprocessable and have self-healing as well as shape-memory properties. %0 journal article %@ 1385-8947 %A Cevallos-Cueva, N.,Rahman, M.M.,Kinfu, H.H.,Abetz, V. %D 2024 %J Chemical Engineering Journal %N %P 152775 %R doi:10.1016/j.cej.2024.152775 %T Mass transport mechanism of nitrate selective nanofiltration membranes on the basis of the Donnan steric pore model with dielectric exclusion (DSPM-DE) %U https://doi.org/10.1016/j.cej.2024.152775 %X Nanofiltration (NF) membranes can play an important role to mitigate the nitrate pollution, emphasizing the necessity for understanding its mass transport mechanism to enhance water purification strategies. This study focuses on the nitrate separation capabilities of thin film composite NF membranes having a polyamide (PA) selective layer. The selective layer of the membranes was fabricated through interfacial polymerization, with varying piperazine (PIP) and trimesoyl chloride (TMC) monomer concentrations on porous polyacrylonitrile substrates. We studied their retention on aqueous solutions of PEG 200, single salts (NaCl, NaNO3, Na2SO4), and mixed salts (NaCl + NaNO3 and NaNO3 + Na2SO4). Through a new fitting scheme, the Donnan Steric Pore Model with Dielectric Exclusion (DSPM-DE) was utilized to correlate the PIP and TMC concentrations with the ion transport and exclusion mechanisms responsible for the membranes’ nitrate separation capabilities. The model could simulate the Na+/NO3-/SO42- system but not Na+/NO3-/CL-. Dielectric exclusion and diffusion were the dominant partitioning and transport mechanisms, respectively, explaining the high retentions of sulfate (96 to 99 %) and the negative retentions of nitrate (−24 to 11 %). This study sheds light on the potential of NF membranes having PA selective layers for efficient nitrate/sulfate separation, providing valuable insights into the underlying transport and exclusion mechanisms. %0 journal article %@ 0955-9930 %A Codrington, J.,Varnum, A.A.,Hildebrandt, L.,Pröfrock, D.,Bidhan, J.,Khodamoradi, K.,Höhme, A.L.,Held, M.,Evans, A.,Velasquez, D.,Yarborough, C.C.,Ghane-Motlagh, B.,Agarwal, A. %A Achua, J.,Pozzi, E.,Mesquita, F.,Petrella, F.,Miller, D.,Ramasamy, R. %D 2024 %J International Journal of Impotence Research %N %P %R doi:10.1038/s41443-024-00930-6 %T Detection of microplastics in the human penis %U https://doi.org/10.1038/s41443-024-00930-6 %X The proliferation of microplastics (MPs) represents a burgeoning environmental and health crisis. Measuring less than 5 mm in diameter, MPs have infiltrated atmospheric, freshwater, and terrestrial ecosystems, penetrating commonplace consumables like seafood, sea salt, and bottled beverages. Their size and surface area render them susceptible to chemical interactions with physiological fluids and tissues, raising bioaccumulation and toxicity concerns. Human exposure to MPs occurs through ingestion, inhalation, and dermal contact. To date, there is no direct evidence identifying MPs in penile tissue. The objective of this study was to assess for potential aggregation of MPs in penile tissue. Tissue samples were extracted from six individuals who underwent surgery for a multi-component inflatable penile prosthesis (IPP). Samples were obtained from the corpora using Adson forceps before corporotomy dilation and device implantation and placed into cleaned glassware. A control sample was collected and stored in a McKesson specimen plastic container. The tissue fractions were analyzed using the Agilent 8700 Laser Direct Infrared (LDIR) Chemical Imaging System (Agilent Technologies. Moreover, the morphology of the particles was investigated by a Zeiss Merlin Scanning Electron Microscope (SEM), complementing the detection range of LDIR to below 20 µm. MPs via LDIR were identified in 80% of the samples, ranging in size from 20–500 µm. Smaller particles down to 2 µm were detected via SEM. Seven types of MPs were found in the penile tissue, with polyethylene terephthalate (47.8%) and polypropylene (34.7%) being the most prevalent. The detection of MPs in penile tissue raises inquiries on the ramifications of environmental pollutants on sexual health. Our research adds a key dimension to the discussion on man-made pollutants, focusing on MPs in the male reproductive system. %0 journal article %@ 2198-3844 %A Appold, M.,Rangou, S.,Glass, S.,Lademann, B.,Filiz, V. %D 2024 %J Advanced Science %N %P 2403288 %R doi:10.1002/advs.202403288 %T Enhanced UV Penetration and Cross-Linking of Isoporous Block Copolymer and Commercial Ultrafiltration Membranes using Isorefractive Solvent %U https://doi.org/10.1002/advs.202403288 %X Amphiphilic block copolymers are promising candidates for the fabrication of ultrafiltration membranes with an isoporous integral asymmetric structure. The membranes are typically fabricated by the combination of block copolymer self-assembly and the non-solvent-induced phase separation (SNIPS) process resulting in isoporous integral asymmetric membranes. Certainly, all these membranes lack thermal and chemical stability limiting the usage of such materials. Within this study, the fabrication of completely cross-linked isoporous integral asymmetric block copolymer membranes is demonstrated by UV cross-linking resulting in chemical and thermal stable ultrafiltration membranes. The UV cross-linking process of PVBCB-b-P4VP (poly(4-vinylbenzocyclobutene)-b-poly(4vinylpyridine)) block copolymer membranes in dependency of irradiation time, intensity, distance between membrane and UV source and the wavelength is investigated. Furthermore, it is shown that the penetration depths can be increased by soaking the membranes in wave-guiding solutions before UV cross-linking is carried out. Moreover, a completely new and easy cross-linking strategy is developed based on isorefractive solvents resulting in thermal and chemically stable membranes that are cross-linked through the whole membrane thickness. Finally, the new cross-linking strategy in isorefractive solutions is transferred to commercial PVDF and PAN-co-PVC polymer membranes paving the way for more stable and sustainable ultrafiltration membranes. %0 journal article %@ 0009-286X %A Pashayev, E.,Kandelhard, F.,Georgopanos, P. %D 2024 %J Chemie - Ingenieur - Technik %N 6 %P 805-812 %R doi:10.1002/cite.202300198 %T Sauerstoffempfindlichkeit der RAFT-Polymerisation – Eine Modellierungsstudie %U https://doi.org/10.1002/cite.202300198 6 %X Die reversible Additions-Fragmentierungs-Kettenübertragungspolymerisation, kurz RAFT (reversible addition-fragmentation chain-transfer polymerization) genannt, ist eine Methode zur kontrollierten Synthese von Blockcopolymeren und stellt eine Alternative zu lebenden ionischen Polymerisationen dar. Obwohl sie im Vergleich zu diesen weniger anfällig für Verunreinigungen ist, führt Sauerstoff zur Inhibierung der Polymerisation. In einer vorhergehenden Studie wurde ein Modell zur Beschreibung der Inhibierungskinetik der RAFT-Polymerisation von Styrol entwickelt. Basierend auf diesem Modell wird eine ausführliche Sensitivitätsanalyse bezüglich der kinetischen Koeffizienten durchgeführt. Während die Bildung der Polyperoxide durch Sauerstoffaddition hohe Reaktionsgeschwindigkeiten aufweist, konnten deren weiteren Reaktionen (Wachstum und Terminierung) als geschwindigkeitsbestimmende Schritte identifiziert werden. Außerdem zeigte sich eine proportionale Abhängigkeit der Dauer der Inhibierung mit der Sauerstoffkonzentration. Auf Basis der gewonnen Erkenntnisse wurde einer neue Initiierungsstrategie unter Verwendung verschiedener thermischer Initiatoren zur Optimierung der Polymerisation anhand von Simulationen erfolgreich getestet. %0 journal article %@ 2046-2069 %A Caliskan, E.,Shishatskiy, S.,Abetz, V.,Filiz, V. %D 2024 %J RSC Advances %N %P 9613-9645 %R doi:10.1039/d3ra08398e %T Pioneering the preparation of porous PIM-1 membranes for enhanced water vapor flow %U https://doi.org/10.1039/d3ra08398e %X In this study, porous polymers of intrinsic microporosity (PIM-1) membranes were prepared by non-solvent induced phase inversion (NIPS) and investigated for water vapor transport in view of their application in membrane distillation (MD). Due to the lack of high boiling point solvents for PIM-1 that are also water miscible, the mixture of tetrahydrofuran (THF) and N-methyl-2-pyrrolidone (NMP) was found to be optimal for the formation of a membrane with a developed porous system both on the membrane surface and in the bulk. PIM-1 was synthesized by using low and high temperature methods to observe how molecular weight effects the membrane structure. Low molecular weight PIM-1 was produced at low temperatures, while high molecular weight PIM-1 was obtained at high temperatures. Several membranes were prepared, including PM-6, PM-9, and PM-11 from low molecular weight PIM-1, and PM-13 from high molecular weight PIM-1. Scanning electron microscopy (SEM) was used to image the surface and cross-section of different porous PIM-1 membranes. Among all the PIM-1 membranes (PM) obtained, PM-6, PM-9, PM-11 and PM-13 showed the most developed porous structure, while PM-13 showed large voids in the bulk of the membrane. Contact angle measurements showed that all PIM-1 porous membranes are highly hydrophobic. Liquid water flux measurements showed that PM-6, PM-9 and PM-11 showed minimal water fluxes due to small surface pore size, while PM-13 showed a high water flux due to a large surface pore size. Water vapor transport measurements showed high permeance values for all membranes, demonstrating the applicability of the developed membranes for MD. In addition, a thin film composite (TFC) membrane with PIM-1 selective layer was prepared and investigated for water vapor transport to compare with porous PIM-1 membranes. The TFC membrane showed an approximately 4-fold lower vapor permeance than porous membranes. Based on these results, we postulated that the use of porous PIM-1 membranes could be promising for MD due to their hydrophobic nature and the fact that the porous membranes allow vapor permeability through the membrane but not liquid water. The TFC membrane can be used in cases where the transfer of water-soluble contaminants must be absolutely avoided. %0 journal article %@ 2168-0485 %A Haida, P.,Chirachanchai, S.,Abetz, V. %D 2023 %J ACS Sustainable Chemistry & Engineering %N 22 %P 8350-8361 %R doi:10.1021/acssuschemeng.3c01340 %T Starch-reinforced Vinylogous Urethane Vitrimer Composites: An Approach to Biobased; Reprocessable and Biodegradable Materials %U https://doi.org/10.1021/acssuschemeng.3c01340 22 %X Vitrimers represent permanent and dynamic polymer networks at the same time. The combination of dynamic covalent bonds and widely available, biodegradable, and biobased raw materials enables new polymers with an excellent carbon footprint, mechanical properties, and outstanding features in terms of multiple recycling methods, e.g., thermomechanical, chemical, and biological reprocessing/reusability. Natural corn starch granules have been surface-modified by an acetoacetylation reaction without using any additional solvent and maintaining the inner semicrystalline structure, giving a polyfunctional cross-linker for starch-reinforced vitrimer composites. Vinylogous urethane vitrimer matrices were synthesized by the condensation reaction of fully acetoacetylated glycerol and different diamines, while glycerol and the diamines were deliberately selected as potentially biobased raw materials. Seven different matrix vitrimers were synthesized with a content of 0–70 wt % of modified starch and investigated in terms of their thermal and mechanical properties. In total, 20 elastomeric and thermosetting materials have been prepared, exhibiting high elastic moduli of 2 GPa with short stress relaxation times and a high content of modified starch up to 70 wt %. The composites show low swelling ratios, suppressing the natural gelatinization of starch in water. Moreover, suitable thermomechanical, chemical, and enzymatic recycling methods for closed-loop cycles, remolding, reusability, and biodegradability were developed. %0 journal article %@ 1022-1352 %A Weerathaworn, S.,Abetz, V. %D 2023 %J Macromolecular Chemistry and Physics %N 1 %P 2200248 %R doi:10.1002/macp.202200248 %T Tailor-Made Vinylogous Urethane Vitrimers Based on Binary and Ternary Block and Random Copolymers: An Approach toward Reprocessable Materials %U https://doi.org/10.1002/macp.202200248 1 %X Vitrimers are promising reprocessable materials. To tune their properties, microphase separated block copolymers as backbones play an essential role in the thermal and mechanical properties of the resulting nanostructured networks. In this study, various narrow disperse di- and triblock copolymers containing a hydroxyethyl methacrylate block and, for comparison, random copolymers of the same comonomers are synthesized in a controlled manner by photoiniferter reversible addition-fragmentation chain transfer polymerization. Subsequently, the copolymers are modified by acetoacetate groups and cross-linked with diamines. After curing, the di- and triblock copolymer-based vitrimers exhibit excellent thermal and mechanical properties compared to random ones; moreover, their characteristic properties can be adjusted by different types and amounts of diamines. As the transamination reaction is a thermoreversible exchange reaction, the resulting vitrimers are reprocessable and therefore are recyclable materials. The combining of two of these classes of soft materials, namely vitrimers and block copolymers, leads to materials with a broad spectrum of adjustable mechanical properties for various applications with an improved end-of-life management, when compared to permanently crosslinked thermosets. %0 journal article %@ 1759-9954 %A Meis, D.,Neumann, S.,Shishatskiy, S.,Meis, U.,Filiz, V. %D 2023 %J Polymer Chemistry %N 5 %P 547-561 %R doi:10.1039/d2py00712f %T Thermally stimulated cascade reaction polymer membranes: a promising strategy for an increased hydrogen and propylene purification performance %U https://doi.org/10.1039/d2py00712f 5 %X Thermally stimulated solid-state reactions, forming polybenzoxazoles, from polyimides were reported about two decades ago, and introduced as promising membrane materials by Park et al. in 2007 Meanwhile most of the reported materials still suffer from low conversions at 400 °C and high TRonset temperatures, or low gas permeabilities, as a result of the increasing flexibility to compensate required annealing temperatures. In our study, we present a comprehensive structure–property–performance relationship, based on thermal-, film- and gas separation investigations, supported by molecular modelling and quantum mechanical simulations. Moreover, the execution of the TR process and other thermally triggered structure formations was performed within a molecular dynamics simulation for the first time. This was done in an amorphous cell and its properties, such as the free volume element characterisation with respect to a structure–property analysis done. Our materials provide among the lowest reported TR temperature and the lowest ever reported onset temperature (γE-PI) for a 6FDA-APAF based TRP and full conversion at 350 °C. βM-PI revealed 22% of TR conversion at an annealing temperature of only 300 °C and 84% at 350 °C, leading to several upper-bound performances, an efficient hydrogen and propylene purification performance, while having a good processability and a high chemical resistance, high TR conversion at low TRonset temperatures. %0 journal article %@ 0376-7388 %A Rahman, M. %D 2023 %J Journal of Membrane Science %N %P 121176 %R doi:10.1016/j.memsci.2022.121176 %T Multiblock copolymers containing polyether segments for separation of C4 hydrocarbons %U https://doi.org/10.1016/j.memsci.2022.121176 %X Separation of C4 paraffins and C4 olefins from each other is an underdeveloped sector of membrane gas separation. Permeabilitieis, diffusivities and solubilities of C4 paraffins (i.e. n-butane and isobutane) and C4 olefins (i.e. cis-2-butene, trans 2-butene, 1-butene, isobutylene and 1,3-butadiene) in three commercial polymers- PEBAX 2533, PolyActive1500PEGT77PBT23 and PolyActive4000PEGT77PBT23 are reported in this study for the first time. The aim of this study is to thoroughly understand the single gas permeation mechanism of the C4 paraffins and C4 olefins through the multiblock copolymers. The cohesive energy density of the polyether segments plays a vital role to determine the permeabilities through the polymer. The selectivity of the olefin/paraffin gas pairs are largely dependent on the content of the ether oxygen of the polyether segments. But the selectivity of the paraffin gas pair and the olefin isomer gas pairs are not influenced by the ether oxygen content of the polyether segments of the multiblock copolymers. %0 journal article %@ 1022-1352 %A Lemich, S.,Sobania, N.,Meyer, N.,Schütz, P.,Hankiewicz, B.,Abetz, V. %D 2023 %J Macromolecular Chemistry and Physics %N 3 %P 2200355 %R doi:10.1002/macp.202200355 %T Synthesis of Multiresponsive Gold@Polymer-Nanohybrid Materials Using Polymer Precursors Obtained by Photoiniferter RAFT Polymerization %U https://doi.org/10.1002/macp.202200355 3 %X Combining gold nanoparticles (GNP) with stimuli-responsive polymers is a fascinating field for applications as sensor materials or in biomedical applications. The synthesis of multi-responsive Au@Polymer hybrid systems in an in-situ approach using tailor-made poly(2-(dimethylamino)ethyl methacrylate) (P(DMAEMA)) precursor synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization is introduced. In particular, because of its multi-responsive behavior, P(DMAEMA) is of great interest and was used as the precursor for the synthesis. For the polymerization of the precursor, we introduce an approach, applying the photoiniferter RAFT (photoRAFT) mechanism applicable for tertiary amine-bearing methacrylic monomers like DMAEMA. By varying the chain transfer agents (CTA), the influence of different RAFT Z-groups on the solubility of the Au-hybrids was studied. Aging effects were observed by transmission electron microscopy (TEM) analyses. A comprehensive dynamic light scattering (DLS) study revealed the thermoresponsive behavior of the Au-hybrids in an aqueous solution. The influence of free polymer in solution on the suspension stability was observed. The capability of crosslinking using 1,5-dibromopentane (DBP) and the CO2 sensitivity of the synthesized hybrids expands the area of their potential application. %0 journal article %@ 2040-3364 %A Simon, A.,Zhang, Z.,Abetz, C.,Abetz, V.,Segal-Peretz, T. %D 2023 %J Nanoscale %N 7 %P 3219-3229 %R doi:10.1039/D2NR05477A %T Atomic layer deposition enables multi-modal three-dimensional electron microscopy of isoporous membranes %U https://doi.org/10.1039/D2NR05477A 7 %X Block copolymer (BCP) membranes are promising materials for water purification. They enable the fabrication of integral asymmetric isoporous membranes with high permeability and good selectivity. Commonly, the characterization of such hierarchical structures is performed by conventional electron microscopy (EM) means, namely scanning and transmission electron microscopy (SEM and TEM, respectively). However, due to the inherent lack of contrast between BCP domains, external contrast agents are required to achieve informative, high-resolution imaging. In addition, such EM techniques are typically limited to a certain cross-section or surface morphology only. In this paper, we harness the selective growth of AlOx in the pore-forming domains of the BCP to create an internal and stable contrast difference between the blocks. This in turn allowed us to perform advanced three-dimensional characterization of the membranes with slice-and-view focused ion beam (FIB)- SEM and TEM tomography, providing an understanding of the 3D structure and properties such as 3D geometry of the pores, 3D tortuosity, and 3D permeability. This 3D characterization also provides better correlations between the membrane structure and its performance. Such knowledge can allow better design and fine-tuning of BCP membranes and other membranes for their applications. %0 journal article %@ 2077-0375 %A Rahman, M. %D 2023 %J Membranes %N 2 %P 164 %R doi:10.3390/membranes13020164 %T Membranes for Osmotic Power Generation by Reverse Electrodialysis %U https://doi.org/10.3390/membranes13020164 2 %X In recent years, the utilization of the selective ion transport through porous membranes for osmotic power generation (blue energy) has received a lot of attention. The principal of power generation using the porous membranes is same as that of conventional reverse electrodialysis (RED), but nonporous ion exchange membranes are conventionally used for RED. The ion transport mechanisms through the porous and nonporous membranes are considerably different. Unlike the conventional nonporous membranes, the ion transport through the porous membranes is largely dictated by the principles of nanofluidics. This owes to the fact that the osmotic power generation via selective ion transport through porous membranes is often referred to as nanofluidic reverse electrodialysis (NRED) or nanopore-based power generation (NPG). While RED using nonporous membranes has already been implemented on a pilot-plant scale, the progress of NRED/NPG has so far been limited in the development of small-scale, novel, porous membrane materials. The aim of this review is to provide an overview of the membrane design concepts of nanofluidic porous membranes for NPG/NRED. A brief description of material design concepts of conventional nonporous membranes for RED is provided as well. %0 journal article %@ 0009-286X %A Kandelhard, F.,Georgopanos, P. %D 2023 %J Chemie - Ingenieur - Technik %N 5 %P 754-760 %R doi:10.1002/cite.202200205 %T A Kinetic and Heat Balance Model for Anionic Batch Block Copolymerization of Styrene and Isoprene %U https://doi.org/10.1002/cite.202200205 5 %X Anionic polymerization is an established process for the synthesis of well-defined block copolymers. Due to the high reaction rates, a good knowledge of the process and its heat generation is of great importance for safe reaction control. This is to be achieved by the development and validation of a combined kinetic and heat transport model. The validation of the combined model was based on the experimentally anionic homo-polymerization of styrene that was expanded for the block co-polymerization of styrene and isoprene carried out in cyclohexane in batch reactors. %0 journal article %@ 0888-5885 %A Kandelhard, F.,Pashayev, E.,Schymura, J.,Georgopanos, P. %D 2023 %J Industrial & Engineering Chemistry Research %N 22 %P 8696–8708 %R doi:10.1021/acs.iecr.3c00607 %T Kinetic Modeling of the Synthesis of Poly(4-Vinylpyridine) Macro-Reversible Addition-Fragmentation Chain Transfer Agents for the Preparation of Block Copolymers %U https://doi.org/10.1021/acs.iecr.3c00607 22 %X Reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the most common controlled polymerization techniques to prepare well-defined, rather narrow dispersed polymers due to reduced demands in reactant preparation. Despite these advantages, RAFT polymerization was so far primarily utilized on small laboratory scales. This study presents a first step to a scaled-up RAFT polymerization by developing and experimentally validating a kinetic model on the example of the polymerization of 4-vinylpyridine (4VP), which to date is not described in the literature. With the implementation of the results from modeling, the synthesis process was extended to a medium scale (from 6 to 36 g), while the same high conversions, molar mass, and low dispersity as in the smaller scale were achieved. The process is also optimized regarding the high degree of livingness necessary for using the 4VP polymers as a macro-RAFT agent in the subsequent reaction step for the synthesis of poly(4-vinylpyridine)-b-polystyrene diblock copolymers by RAFT dispersion polymerization. %0 journal article %@ 1862-8338 %A Pashayev, E.,Kandelhard, F.,Georgopanos, P. %D 2023 %J Macromolecular Reaction Engineering %N 2 %P 2200068 %R doi:10.1002/mren.202200068 %T Experimental & Modelling Digital Twin Approach for Polymer Synthesis via Re-initiated Oxygen inhibited RAFT Polymerization %U https://doi.org/10.1002/mren.202200068 2 %X Controlled polymerization techniques like the reversible-addition fragmentation chain transfer polymerization (RAFT) are sensitive to impurities such as oxygen. This work explores the application of re-initiation as a tool to enhance monomer conversion. A kinetic model for the oxygen inhibited RAFT dispersion polymerization for the synthesis of poly(4-vinylpyridine)-b-polystyrene (P4VP-b-PS) is developed. Thus, using the kinetic model, the re-initiation of the inhibited RAFT polymerization is partially (monomer conversion ≤10%) predicted. By implementing the re-initiation as a solution the synthesis of P4VP-b-PS copolymers with the high conversion (>96%) and a good dispersity (≤1.2) is enabled. %0 journal article %@ %A Schymura, J.,Held, M.,Georgopanos, P. %D 2023 %J Macromolecular Chemistry and Physics %N 15 %P 2300119 %R doi:10.1002/macp.202300119 %T Scale-Up synthesis of thermoresponsive polymer particles from poly(N;N-dimethylacrylamide-co-N-isopropylacrylamide)-b-polystyrene via RAFT emulsion polymerization %U https://doi.org/10.1002/macp.202300119 15 %X In this work, the reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization of poly(N,N-dimethylacrylamide-co-N-isopropylacrylamide)-b-polystyrene is developed with the aim of scale-up of the polymer synthesis. Influences on the stability of the emulsion, reaction kinetics, and product quality are examined, compared between small-scale and bench-scale syntheses, and discussed in detail. The block copolymer lattices are studied via temperature-dependent dynamic light scattering measurements in order to investigate the effects of the scale-up on the thermosensitive behavior of the block copolymer and on emulsion stability. Conversion determination and polymer characterization are attained through 1H nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography, respectively. The emulsion polymerization is successfully scaled up after several changes in the reaction composition and shows promising results regarding desired properties of the polymer. %0 journal article %@ 0024-9297 %A Dreyer, O.,Schneider, L.,Radjabian, M.,Abetz, V.,Müller, M. %D 2023 %J Macromolecules %N 17 %P 6880-6890 %R doi:10.1021/acs.macromol.3c01220 %T Evaporation-induced self-assembly of diblock copolymer films in an electric field: a simulation study %U https://doi.org/10.1021/acs.macromol.3c01220 17 %X The self-assembly of cylinder-forming diblock copolymer solutions in the course of solvent evaporation in the presence of an electric field is studied by particle-based simulations. The electric field provides additional control of the evaporation-induced self-assembly (EISA) and enlarges the processing window, which results in the desired formation of cylindrical domains that are perpendicularly oriented to the film surface. Two effects of the electric field are highlighted: (i) If the components of the AB block copolymer exhibit different permittivities, dielectrophoretic forces align the internal AB interfaces along the electric field, rendering parallel cylinders unstable. (ii) If shallow density gradients in the course of EISA give rise to the unfavorable morphology of perpendicular cylinders and subjacent layers of spherical micelles, the application of an electric field results in an elongation of the cylindrical domains and suppresses sphere formation. The beneficial effect of an electric field can be rationalized by the layer evolution model (LEM), previously developed for EISA in the absence of an electric field. %0 journal article %@ 1759-9954 %A Hub, L.,Koll, J.,Radjabian, M.,Abetz, V. %D 2023 %J Polymer Chemistry %N %P 3063-3074 %R doi:10.1039/D3PY00241A %T Blue light-induced iniferter RAFT polymerization in aqueous-alcoholic media as a universal tool for the homopolymerization of various monomer families: kinetic investigations in different scales %U https://doi.org/10.1039/D3PY00241A %X Photo-iniferter RAFT polymerization offers an opportunity to synthesize polymers without the requirements of external initiators. Blue light-induced iniferter RAFT polymerization was performed in a water–ethanol mixture (50 : 50 w/w) as an environmentally friendly, facile and tunable method to prepare well-defined homopolymers of different monomer classes like poly(N,N-dimethylacrylamide) (PDMA), poly(2-dimethylamino ethylacrylate) (PDMAEA) and poly(vinylpyridines) (PVPs). Homopolymers were synthesized on different laboratory scales between 1 g and 75 g. The influence of light intensity and temperature on polymerizations on different scales was investigated. Polymerization conditions were optimized and narrow molecular weight-distributed PDMA (Đ = 1.08–1.30), PDMAEA (Đ = 1.21–1.42), P4VP (Đ = 1.07–1.31) and P2VP (Đ = 1.14–1.35) were synthesized on larger laboratory scales and in short polymerization times (≤ 6 h). This study highlights the versatile usability and adaptability of visible light-induced RAFT polymerization for larger polymer production in a batch process. %0 journal article %@ 0376-7388 %A Raje, A.,Koll, J.,Schneider, E.S.,Georgopanos, P. %D 2023 %J Journal of Membrane Science %N %P 121837 %R doi:10.1016/j.memsci.2023.121837 %T A novel organic solvent-free method for manufacturing polyethersulfone hollow fiber membranes using melt extrusion %U https://doi.org/10.1016/j.memsci.2023.121837 %X Hollow fiber membranes are traditionally manufactured using the spinning process, which takes advantage of the phase separation/inversion for the creation of a porous structure. In this work, the use of melt extrusion led to the fabrication of hollow fiber membranes without the use of organic solvents. Following post-treatment, the fabricated partially dense fibers are transformed into porous fibers. In detail, ternary blends of polyethersulfone/poly(ethylene glycol)/poly(N-vinyl pyrrolidone) (PESU/PEG/PVP) were developed by combining a solvent-free liquid mixture of PEG/PVP into PESU. Using a single screw extruder, this blend was melted and extruded using an annular slit nozzle where PEG functioned as a plasticizer, i.e., decreased processing temperatures, while PVP aided in retaining the hollow fiber geometry. These hollow fibers were comprised of uniformly closed pores, occurring due to the expansion and formation of bubbles of evaporating PEG nucleated by PVP during extrusion. By immersing these fibers into an aqueous solution of sodium hypochlorite (NaOCl), PEG and PVP were removed, which led to an open porous structure with pore sizes between 100 nm and 1 μm throughout the membrane. The outer surfaces of the hollow fibers were found to contain a higher PVP content than the inner surface. As PVP and PESU are miscible, i.e., blended in a single phase, treatment with NaOCl led to the creation of open pores on the outer surface with pore sizes between 10 and 150 nm, thus deeming the outer surface functional as a separation layer. The effect of blend composition, extrusion settings, and post-treatment parameters on membrane morphology, water flux, thermal characteristics, and tensile strength was studied, while after the modification, near-pristine PESU membranes were pursued. A water-flux of 28 L/h m2 bar and a molecular weight cut-off (MWCO) of 90%, 75%, and 40% for poly(ethylene oxide) of an average of 1000 kDa, 400 kDa, and 100 kDa molecular weight, respectively, proved that via extrusion it is possible to produce hollow fiber membranes for ultrafiltration without the use of organic solvents. %0 journal article %@ 2214-8604 %A Winhard, B.F.,Haida, P.,Plunkett, A.,Katz, J.,Domènech, B.,Abetz, V.,Furlan, K.P.,Schneider, G.A. %D 2023 %J Additive Manufacturing %N %P 103776 %R doi:10.1016/j.addma.2023.103776 %T 4D-Printing of Smart, Nacre-Inspired, Organic-Ceramic Composites %U https://doi.org/10.1016/j.addma.2023.103776 %X Additive manufacturing of shape memory polymers has gained tremendous interest in recent years due to their versatile potential applications in various industries, such as biomedicine and aerospace. However, the polymers' mechanical properties, specifically stiffness and strength, often hinder their use in mechanically demanding applications, e.g. as structural materials. In this work we produced nacre-inspired composites with a covalent adaptable network, which enables fast and mechanically lossless self-healing, reshaping, and shape memory capabilities. We demonstrate a novel direct write 4D-printing strategy to print smart, nacre-inspired, organic-ceramic composites based on alumina platelets and vitrimers with up to 3.3 and 26.7 times higher tensile strength and stiffness, respectively, in comparison to the pristine vitrimer. To the best of our knowledge, we introduce for the first time a single step 4D-printing process for nacre-inspired composites, that exploits suspension spreading to align micron sized alumina platelets along a common plane, and which utilizes solvent evaporation to induce polycondensation of the monomers resulting in a vinylogous urethane vitrimer after extrusion of the suspension. This work presents a facile, direct write 4D-printing strategy at ambient printing conditions, establishing a foundation for adaptive additive manufacturing of smart organic-ceramic composites of interest to various industries. %0 journal article %@ 0009-286X %A Wolff, T.,Brinkmann, T.,Scholles, C.,Kerner, M. %D 2023 %J Chemie - Ingenieur - Technik %N %P %R doi:10.1002/cite.202300099 %T Membranbasierte Bereitstellung von CO2 für die dezentrale Algenproduktion in einer Bioenergiefassade %U https://doi.org/10.1002/cite.202300099 %X Diese Studie unterstreicht die Bedeutung einer nachhaltigen Energieversorgung im Hinblick auf den Klimawandel. Es wird ein Weg aufgezeigt, wie eine dezentrale Wärmeversorgung in städtischen Gebieten basierend auf erneuerbaren Energien mit einer Algenproduktion kombiniert werden kann. Die dezentral erzeugten CO2-Emissionen werden mittels Membrantrenntechnik für die Biomasseproduktion nutzbar gemacht. Das Betriebsverhalten der CO2-selektiven Membranmaterialien wurde über einen Betriebszeitraum von fast 10 Jahren beobachtet. Dies liefert einen soliden Nachweis für die Betriebsbereitschaft der Polymermembran und der Membranmodultechnologie. So wird eine weitere Optimierung des Trennverfahrens für zukünftige Anwendungen, auch in einem breiteren Einsatzspektrum, ermöglicht. %0 journal article %@ 0009-286X %A Abetz, V. %D 2023 %J Chemie - Ingenieur - Technik %N 9 %P 1361-1371 %R doi:10.1002/cite.202300066 %T Filtrationsmembranen und spezifische Adsorber auf der Basis von maßgeschneiderten selbst-organiserenden Blockcopolymeren %U https://doi.org/10.1002/cite.202300066 9 %X Blockcopolymere bieten aufgrund ihrer Fähigkeit, selbstorganisierte Strukturen zu bilden, verschiedene Möglichkeiten für die Stofftrennung. Flach- und Hohlfadenmembranen mit regelmäßig angeordneten Poren gleichen Durchmessers und hoher Porenzahldichte können aus selbstorganisierenden Blockcopolymeren hergestellt werden. Die Porengrößen und Funktionalitäten dieser Membranen und damit deren Einsatzmöglichkeiten in der Stofftrennung können auf verschiedenen Wegen eingestellt werden, wobei die Einstellung dieser Parameter an fertigen Membranstrukturen besonders interessant ist. Weiterhin können maßgeschneiderte amphiphile Blockcopolymere zur spezifischen Extraktion von Stoffen aus wässrigen (hydrophilen) Lösungen in organische (hydrophobe) Lösungen eingesetzt werden. %0 journal article %@ 2666-8211 %A Hamedimastanabad, H.,Brinkmann, T.,Wolff, T. %D 2023 %J Chemical Engineering Journal Advances %N %P 100541 %R doi:10.1016/j.ceja.2023.100541 %T Techno-economic assessment of H2 extraction from natural gas distribution grids: A novel simulation-based optimization framework for pressure swing adsorption processes %U https://doi.org/10.1016/j.ceja.2023.100541 %X Green H2 plays an important role in the global energy transition. To improve its supply chain economics, the already existing gas grids can be an interim solution for its storage and transportation infrastructure. Injecting H2 into the gas networks seems straightforward from a process design standpoint. However, the extraction, at the other end of the supply chain, poses challenges, and its feasibility from the techno-economic viewpoint is crucial and can support the further development of such programs. This article presents a rigorous techno-economic and optimization model for this process developed in Aspen Adsorption V11 and MATLAB. This holistic model uses the cyclic steady-state approach of Aspen Adsorption V11, which avoids the redundant computations for achieving the steady-state performance in the dynamic simulation approach and allows for the development of a novel simulation-based optimization framework. The proposed optimization model can be used in other pressure swing adsorption applications to improve the rigorousness of the optimal solution and computational time. The results show that H2 extraction from a distribution grid with 30 mol% H2 and 70 mol% CH4 at 12 bar operating pressure costs $0.8064/kg-H2 and $0.9012/kg-H2 for product purities of 99.00 mol% and 99.97 mol%, respectively. Additionally, this study explores the impact of N2 and CO2 presence in natural gas on H2 separation costs. For natural gas containing CH4: CO2: N2 with a molar ratio of 95:2:3 mixed with 30 mol% H2, the separation cost of the 99.00 mol% pure H2 increases by 11.6% to $0.8998/kg-H2; however, based on the simulation, the purity of 99.97 mol% due to the presence of N2 is not technically achievable. %0 journal article %@ 0376-7388 %A Kinfu, H.H.,Rahman, M.M.,Schneider, E.S.,Cevallos-Cueva, N.,Abetz, V. %D 2023 %J Journal of Membrane Science %N %P 121709 %R doi:10.1016/j.memsci.2023.121709 %T Charge and size selective thin film composite membranes having tannic acid – Ferric ion network as selective layer %U https://doi.org/10.1016/j.memsci.2023.121709 %X Selective membranes that can distinguish between solutes of different physicochemical properties are highly desirable for membrane applications such as nanofiltration. Rapid coordination complex formation of metals and polyphenols triggered the development of thin film composite membranes in the last decade through a green synthesis procedure, eliminating the use of toxic organic solvents. In this work, thin film composite membranes with high selectivity between organic solutes were prepared. They contain a selective layer based on a metal-polyphenol network (tannic acid – ferric ion (TA-Fe3+)) with a thickness of approximately 10 nm thickness. The thin layer was obtained by coating aqueous solutions of the two components on top of a microporous polyacrylonitrile support in a sequential mode. The morphological, chemical and physical properties of the membranes were investigated. The results demonstrate that hydrophilicity, surface charge, and pore size of the membranes can be fine-tuned by varying the TA/Fe3+ ratio of the casting solutions. The separation performance of the membranes was further analyzed by filtration tests. For instance, selectivities in the range of 3.2–20.6 were achieved between uncharged(0)/(−)charged dyes of comparable molecular size, while exhibiting a good selectivity, reaching up to 3 times, between monovalent to trivalent negatively charged dyes. This work paves a way to eco-friendly membrane synthesis for diverse applications in water and wastewater treatment. %0 journal article %@ 0376-7388 %A Zhang, Z.,Rahman, M.,Bajer, B.,Scharnagl, N.,Abetz, V. %D 2022 %J Journal of Membrane Science %N %P 120266 %R doi:10.1016/j.memsci.2022.120266 %T Highly selective isoporous block copolymer membranes with tunable polyelectrolyte brushes in soft nanochannels %U https://doi.org/10.1016/j.memsci.2022.120266 %X We used partial crosslinking of the pore-forming block of quaternized PS-b-P4VP integral asymmetric isoporous membranes as a tool to control the effective pore size in aqueous and alcoholic media. A versatile top-down membrane post-modification approach using a combination of difunctional and monofunctional alkyl halide was employed to obtain well-defined nanochannels containing polyelectrolyte brushes. Mild and scalable gas-solid reactions were used for the membrane post-modification. The permeance of the modified membranes changed systematically over a wide range, proving the potential of using the membrane post-modification technique to tailor the pore size from ultrafiltration to nanofiltration regime. Using a membrane post-modification technique, for the first time a series of integral asymmetric isoporous membranes having equal charge density but distinct effective pore size was successfully prepared. The separation performance based on size and charge is demonstrated by separating 1–2 nm organic molecules (having molecular weights in the range of 248–480 g mol−1) with excellent selectivity and permeance. For example, one of the prepared membranes showed a 2.4 times higher retention of methylene blue (MB+, 319.85 g mol−1) than chrysoidine G (CG+, 248.71 g mol−1) from an aqueous feed solution containing equimolar MB+ and CG + while the permeance was 134 Lm−2h−1bar−1. %0 journal article %@ 1759-9954 %A Haida, P.,Signorato, G.,Abetz, V. %D 2022 %J Polymer Chemistry %N 7 %P 946-958 %R doi:10.1039/D1PY01237A %T Blended vinylogous urethane/urea vitrimers derived from aromatic alcohols %U https://doi.org/10.1039/D1PY01237A 7 %X Vitrimers belong to the class of covalent adaptable networks and are cross-linked polymers, which undergo dynamic, associative exchange reactions under thermal treatment, making these networks permanent as well as dynamic. In this work a feasible synthesis route for the acetoacetylation of aromatic alcohols, which expands the selection of acetoacetate monomers for the synthesis of vitrimers, is introduced. Bisphenol-A, resorcin, 2,7-naphthalenediol and 1,1,1-tris(4-hydroxyphenyl)ethane are chosen as examples for commercially relevant di- and trifunctional alcohols used for countless applications, e.g. epoxy resins, phenolic resins and polyester-networks, which are in general not reprocessable. In contrast, aromatic alcohols provide the basis for the prepared vitrimers, representing a reprocessable alternative to the established materials. Model studies are conducted to enlighten the undergoing condensation, substitution and transamination reactions in the emerging vinylogous urethane/urea mixtures, investigating solvent and catalyst effects and determining activation energies. Utilizing the findings from the model studies for the preparation of vitrimers, 16 elastomeric and thermosetting blended poly(vinylogous urethane/urea) networks are prepared by bulk/solvent polymerization, showing short stress-relaxation times of up to 0.7 s at 130 °C and activation energies of ca. 45–150 kJ mol−1 with a broad range of material properties. Moreover, the materials show remarkable reprocessing, reshaping, shape-memory and self-healing properties. %0 journal article %@ 2212-9820 %A Escorihuela, S.,Cerdá-Moreno, C.,Weigelt, F.,Remiro-Buenamanana, S.,Escolástico, S.,Tena, A.,Shishatskiy, S.,Brinkmann, T.,Chica, A.,M. Serrra, J. %D 2022 %J Journal of CO2 Utilization %N %P 101813 %R doi:10.1016/j.jcou.2021.101813 %T Intensification of catalytic CO2 methanation mediated by in-situ water removal through a high-temperature polymeric thin-film composite membrane %U https://doi.org/10.1016/j.jcou.2021.101813 %X Catalytic CO2 methanation technology can be improved by process intensification, i.e. enabling higher energy efficiency and process sustainability. Here, thin-film composite membranes (TFCM) were developed for in-situ water removal in a catalytic membrane reactor (CMR) for the Sabatier process. The selective separation layer (1.4 μm-thick) of the composite membrane is made of the polyimide 6FDA-6FpDA, a glassy polyimide, which exhibits high permeability and selectivity together with stable function at unprecedented high temperatures (>200 °C), compared to polyimides reported until now (90 °C), thus matching the temperature range of Sabatier reactors. Remarkably, TFCM developed in this work, allow to extract an outstanding amount of water up to 1 m3/(m2·h·bar) at 260 °C. TFCM was implemented for the water removal from the methanation reaction in a CMR operated at 260 °C and using Ni-Todorokite as catalyst. The TFCM-mediated water-extraction enabled to raise both catalytic stability and activity during CMR operation. CO2 conversion stability was greatly improved exhibiting a conversion value of 72 % during the course of the reaction (21 % increase in CO2 conversion), with a water removal of 12.5 % and specific flux of ∼100 g·h−1 m−2. %0 journal article %@ 2073-4360 %A Raje, A.,Buhr, K.,Koll, J.,Lillepärg, J.,Abetz, V.,Handge, U. %D 2022 %J Polymers %N 6 %P 1177 %R doi:10.3390/polym14061177 %T Open-Celled Foams of Polyethersulfone/Poly(N-vinylpyrrolidone) Blends for Ultrafiltration Applications %U https://doi.org/10.3390/polym14061177 6 %X Since membranes made of open porous polymer foams can eliminate the use of organic solvents during their manufacturing, a series of previous studies have explored the foaming process of various polymers including polyethersulfone (PESU) using physical blowing agents but failed to produce ultrafiltration membranes. In this study, blends containing different ratios of PESU and poly(N-vinylpyrrolidone) (PVP) were used for preparation of open-celled polymer foams. In batch foaming experiments involving a combination of supercritical CO2 and superheated water as blowing agents, blends with low concentration of PVP delivered uniform open-celled foams that consisted of cells with average cell size less than 20 µm and cell walls containing open pores with average pore size less than 100 nm. A novel sample preparation method was developed to eliminate the non-foamed skin layer and to achieve a high porosity. Flat sheet membranes with an average cell size of 50 nm in the selective layer and average internal pore size of 200 nm were manufactured by batch foaming a PESU blend with higher concentration of PVP and post-treatment with an aqueous solution of sodium hypochlorite. These foams are associated with a water-flux up to 45 L/(h m2 bar). Retention tests confirmed their applicability as ultrafiltration membranes. %0 journal article %@ 1744-683X %A Oral, I.,Abetz, V. %D 2022 %J Soft Matter %N 5 %P 934-937 %R doi:10.1039/d1sm01815a %T Improved alkali metal ion capturing utilizing crown ether-based diblock copolymers in a sandwich-type complexation %U https://doi.org/10.1039/d1sm01815a 5 %X The compexation behavior of metals with free crown ethers (CE) and diblock copolymer-based CE is investigated. The latter shows at least 10 000 times stronger complexation than free CEs. On this basis, a highly stable CE complex within the polymer for efficient extraction of metal ions from low concentrations, e.g. lithium in seawater, is presented. %0 journal article %@ 2365-709X %A Abetz, C.,Georgopanos, P.,Pistidda, C.,Klassen, T.,Abetz, V. %D 2022 %J Advanced Materials Technologies %N 11 %P 2101584 %R doi:10.1002/admt.202101584 %T Reactive Hydride Composite Confined in a Polymer Matrix: New Insights into the Desorption and Absorption of Hydrogen in a Storage Material with High Cycling Stability %U https://doi.org/10.1002/admt.202101584 11 %X Hydrogen is key to the transformation of today's energy technology toward a sustainable future without carbon dioxide emissions. Hydrogen can be produced from water using renewable or sustainable energy sources such as solar or wind power. It can buffer fluctuations between energy generation and use in all energy sectors, stationary heat, and power, as well as mobility. Safe, fast, and easy to handle solutions for storing and releasing hydrogen are essential for the implementation of hydrogen technology. Among the storage alternatives, metal hydride materials represent a safe and efficient option. For the first time, detailed investigations of the local chemical changes in a confined hydrogen storage material before and after 21 hydrogen-unloading and loading cycles are reported. The system is based on micrometer-sized reactive hydride composite (RHC) particles, namely 6Mg(NH2)2 + 9LiH + 1LiBH4, dispersed in a matrix of poly(4-methyl-1-pentene) (TPXTM). The morphological stability of the confined RHC particles during the reversible and almost complete reaction with hydrogen is visualized in detail, explaining the excellent long-term cycling stability. %0 journal article %@ 2666-8211 %A Hamedi, H.,Brinkmann, T. %D 2022 %J Chemical Engineering Journal Advances %N %P 100249 %R doi:10.1016/j.ceja.2022.100249 %T Valorization of CO2 to DME using a membrane reactor: A theoretical comparative assessment from the equipment to flowsheet level %U https://doi.org/10.1016/j.ceja.2022.100249 %X Carbon utilization plays a pivotal role in the circular carbon economy approach. However, CO2 conversion technologies, including thermocatalytic hydrogenation approaches, entail several challenges such as thermodynamic limits and low kinetic rates. In the pursuit of eliminating these two hurdles, this study aims to highlight the unique synergy and high potential of the combination of two emerging technologies: catalytic zeolite membrane reactor and direct dimethyl ether synthesis over hybrid catalysts of Cu/ZnO/Al2O3/HZSM-5. To this end, an equation-based pseudo homogenous model for a plug flow membrane reactor, previously developed in Aspen Custom Modeler, will be verified using experimental data in the literature and then coupled with the appropriately selected kinetic models, which describe this particular reaction system accurately. This enables us to confidently identify the impact of several membrane reactor's characteristics and process parameters on the conversion and selectivity. We also analyze a membrane-reactor-based dimethyl ether synthesis process and compare it with the conventional counterpart. According to our results, at 7.5 MPa pressure, a membrane-based process design offers 1.5%, 44.5% and 69.4% savings in power, heating and refrigerant utilities, respectively. These reductions correspond to 7.3% improvement in CO2 utilization efficiency as a metric to compare the environmental performance of emerging green fuel/chemicals. %0 journal article %@ 2073-4360 %A Shishatskiy, S.,Makrushin, V.,Levin, I.,Merten, P.,Matson, S.,Khotimskiy, V. %D 2022 %J Polymers %N 3 %P 462 %R doi:10.3390/polym14030462 %T Effect of Immobilization of Phenolic Antioxidant on Thermo-Oxidative Stability and Aging of Poly(1-trimethylsilyl-1-propyne) in View of Membrane Application %U https://doi.org/10.3390/polym14030462 3 %X The effect of phenolic antioxidant Irganox 1076 on the structure and gas permeation behavior of poly(1-trimethylsilyl-1-propyne) (PTMSP) was investigated. Isotropic films as well as thin film composite membranes (TFCM) from pure PTMSP and with added antioxidant (0.02 wt%) were prepared. PTMSP with antioxidant has a significantly higher thermal degradation stability in comparison to pure polymer. The thermal annealing of isotropic films of PTMSP with antioxidant was carried out at 140 °C. It revealed the stability of gas permeation properties for a minimum of up to 500 h of total heating time after a modest permeation values decrease in the first 48 h. X-ray diffraction data indicate a decrease in interchain distances during the heat treatment of isotropic films and indicate an increase in the packing density of macromolecules during thermally activated relaxation. Isotropic films and TFCMs from pure PTMSP and with antioxidant stabilizer were tested under conditions of constant O2 and N2 flow. The physical aging of thick and composite PTMSP membranes point out the necessity of thermal annealing for obtaining PTMSP-based membranes with predictable properties. %0 journal article %@ 1744-683X %A Xu, J.,Abetz, V. %D 2022 %J Soft Matter %N 10 %P 2082-2091 %R doi:10.1039/D1SM01692J %T Double thermoresponsive graft copolymers with different chain ends: feasible precursors for covalently crosslinked hydrogels %U https://doi.org/10.1039/D1SM01692J 10 %X The tailored synthesis of graft copolymers from acrylic and methacrylic monomers can be accomplished solely through photoiniferter reversible addition−fragmentation chain transfer (RAFT) polymerization. Samples with poly[oligo(ethylene glycol) methacrylate] (POEGMA) backbones synthesized under green light irradiation and poly(N-isopropylacrylamide) (PNIPAM) side chains growing under blue light irradiation are presented. As monitored by temperature-dependent dynamic light scattering (DLS) measurements and temperature-variable nuclear magnetic resonance (NMR) spectroscopy, the architecture of the graft copolymers allows unique two-step lower critical solution temperatures (LCST) transitions in aqueous solutions. Meanwhile, different end-groups introduced by the corresponding RAFT agents affect the detailed thermoresponsive behavior remarkably. This RAFT strategy shows more advantages when the multiple trithiocarbonate groups are converted into thiol reactive pyridyl disulfide (PDS) groups via a facile post-polymerization modification. The PDS-terminated graft copolymer can then be regarded as a usable precursor for various applications, such as thermoresponsive hydrogels. %0 journal article %@ 2077-0375 %A Gkika, D.,Filiz, V.,Rangou, S.,Kyzas, G.,Mitropoulos, A. %D 2022 %J Membranes %N 4 %P 433 %R doi:10.3390/membranes12040433 %T Cost Profile of Membranes That Use Polymers of Intrinsic Microporosity (PIMs) %U https://doi.org/10.3390/membranes12040433 4 %X Assessing the financial impact of polymers of intrinsic microporosity, otherwise known as PIMs, at the lab scale has been impeded by the absence of a holistic approach that would envelop all related financial parameters, and most importantly any indirect costs, such as laboratory accidents that have been consistently neglected and undervalued in past assessments. To quantify the cost of PIMs in relation to the risks befalling a laboratory, an innovative cost evaluation approach was designed. This approach consists of three stages. Firstly, a two-fold “window of opportunity” (WO) theory is suggested, dividing the total cost profile into two segments, followed up by a qualitative risk analysis to establish the potential cost components. The last stage builds on a total cost of ownership model, incorporating the two types of WO. The total cost of ownership (TCO) approach was selected to ascertain the costs and construct the cost profile of PIMs, according to laboratory experimental data. This model was applied to the synthesis and physicochemical characterization processes. The quantitative analysis revealed that the most influential parameters for synthesis are accidents and energy costs. This is in contrast with the physicochemical characterization process, where the most important determinant is the energy cost. %0 journal article %@ 0897-4756 %A Meis, D.,Neumann, S.,Filiz, V. %D 2022 %J Chemistry of Materials %N 7 %P 3028-3041 %R doi:10.1021/acs.chemmater.1c03939 %T Reactive Multifunctional Polymer Films Using Thermally Stimulated Cascade-like Reactions: Potential Strategy Employing Modified ortho-Allylation in Polyimides %U https://doi.org/10.1021/acs.chemmater.1c03939 7 %X Polymeric materials, undergoing thermally stimulated reaction cascades, are promising materials and techniques for future custom tailoring of high-performance materials, such as in coating or film, heat resistance, and energy applications. The high atom economy and stimulation in the solid state of readily processable precursors, which lead to complex and usually difficult-to-process materials, make them highly attractive when it comes to the design of new materials. Polyimides and polybenzoxazoles are both known as thermally resistant high-performance materials. Polyimides have been used for the conversion to polybenzoxazoles (PBO) at high temperatures. In our study, we report a set of allylated ortho-hydroxy polyimides (HPIs) that are capable of undergoing a set of consecutive thermally stimulated reactions in a reaction cascade-like manner. The reactions have been investigated in detail by thermokinetic and spectroscopic experiments, supported by means of quantum chemical and molecular dynamic simulations. A significant change regarding the extent of consecutive Claisen rearrangement reactions was observed, depending on the type of allyl derivative and course of annealing. βM-PI thus showed a very high conversion to benzofuran rings, followed by an HPI-to-PBO rearrangement to full conversion at an annealing procedure using only 350 °C, which is the highest conversion at a sub-400 °C annealing protocol for a fluorinated HPI. This is even surpassed in our study by γE-PI, which shows the lowest ever reported onset temperature for a modified HPI and especially for a hexafluoroisopropylidene group-containing HPI backbone, which has been identified as a promising backbone material for membrane applications. These results point out that applying thermal reaction cascades, using modified allyl groups in polyimides, could be a universal strategy to improve the materials’ performance of polyimides for various applications. %0 journal article %@ 1022-1352 %A Xu, J.,Abetz, V. %D 2022 %J Macromolecular Chemistry and Physics %N 15 %P 2200058 %R doi:10.1002/macp.202200058 %T Synthesis of a Degradable Hydrogel Based on a Graft Copolymer with Unexpected Thermoresponsiveness %U https://doi.org/10.1002/macp.202200058 15 %X Incorporating multiple pyridyl disulfide (PDS) moieties into polymer chains allows the fabrication of a chemically cross-linked hydrogel through the rapid thiol–disulfide exchange reaction. By aminolysis in the presence of 2,2′-dithiodipyridine (DTP), the end groups of polymers synthesized via reversible addition−fragmentation chain transfer (RAFT) polymerization can readily be converted into PDS-groups. In this contribution, a RAFT-synthesized graft copolymer with thermoresponsive poly[di(ethylene glycol) methyl ether methacrylate] forming the backbone and hydrophilic poly(N,N-dimethylacrylamide) as the side chains is presented. The copolymer chains exhibit surprisingly a two-step lower critical solution temperature transition in aqueous solutions. After modification of the end groups of the backbone and side chains, the PDS-terminated chains can react with a dithiol cross-linker to form a thermoresponsive hydrogel. In a reducing environment, the cleavable disulfide linkages lead to on-demand dissolution of the hydrogel. The resulting thiol-terminated chains undergo a reversible sol–gel transition in response to redox variations, expanding the potential application areas of such a polymer system. %0 journal article %@ 1383-5866 %A Oral, I.,Tamm, S.,Herrmann, C.,Abetz, V. %D 2022 %J Separation and Purification Technology %N %P 121142 %R doi:10.1016/j.seppur.2022.121142 %T Lithium selectivity of crown ethers: The effect of heteroatoms and cavity size %U https://doi.org/10.1016/j.seppur.2022.121142 %X Lithium is a metal in increasingly high demand due to its use in lithium-ion batteries. However, the extraction from aqueous resources as brines and seawater, which account for a major percentage of worldwide Li+ reserves, is challenging due to the presence of other interfering metal ions. Crown ethers (CEs) are known to complex metal cations very effectively, but a fundamental understanding of their potential in lithium extraction is still lacking. Therefore, the selective complexation of Li+ over other alkaline (Na+, K+) and alkaline earth metal (Mg2+, Ca2+) ions is investigated by density functional theory (DFT) calculations for 15–, 12–, and 9–membered CEs and their derivatives containing in part nitrogen and sulfur instead of oxygen atoms. Structure optimizations of these CEs are performed in vacuum, and complex stabilities are discussed by evaluating the cavity size, the distances between donor atoms and metal ion, and by performing Hirshfeld charge and Natural Bond Orbital analyses. The qualitative trends obtained from these methods are in good agreement with the complex stabilities, which suggests that they can be used to make simplified predictions of complex stabilities. The selectivity for Li+ compared to Mg2+ in vacuum can be strongly influenced by the ring size, which was the best for B15C5. The general accuracy of DFT is validated by comparing calculations in a polarizable continuum model with the results of a liquid–liquid extraction in a water/dichloromethane mixture using the exemplary extraction of Li+, Na+, K+, Mg2+, and Ca2+ by aza–15–crown–5. By doing so, the DFT trends are confirmed (with the stability of the Mg2+ complex being overestimated while all others are underestimated), suggesting that DFT is a valuable tool for optimizing CE structures to selectively complex Li+ or other metal ions. In the context of increasing global lithium demand, the results of this study can serve the further development of selective and sustainable lithium extraction from the largely unexploited resource of seawater. %0 journal article %@ 1098-2329 %A Harden, F.,Kargar, M.,Handge, U. %D 2022 %J Advances in Polymer Technology %N %P 5602902 %R doi:10.1155/2022/5602902 %T Influence of Carbon Dioxide on the Glass Transition of Styrenic and Vinyl Pyridine Polymers: Comparison of Calorimetric, Creep, and Rheological Experiments %U https://doi.org/10.1155/2022/5602902 %X The glass transition of amorphous polymers determines the mobility of polymer chains and the time scale of relaxation processes. The glass transition temperature is reduced by the presence of low molecular weight molecules, e.g., dissolved gases or organic solvents. The quantitative knowledge of reduction of the glass transition temperature caused by the addition of carbon dioxide in a polymer melt is highly relevant for foam extrusion. However, measurement of the reduction of glass transition temperature caused by gas loading has to be performed under elevated pressure which implies high experimental efforts. In this work, we discuss and compare three methods for determination of the influence of carbon dioxide on thermal properties of amorphous polymers, i.e., calorimetric measurements, creep tests, and rheological experiments. The advantages and disadvantages of these methods are elucidated. Furthermore, the influence of molecular structure of the styrenic and vinylpyridine polymers on the glass transition temperature is discussed. Polystyrene generally shows the highest reduction of glass transition temperature. Poly(2-vinylpyridine) and poly(4-vinylpyridine) show a slightly less pronounced behaviour in comparison to polystyrene because of the lower polarity of polystyrene. Poly(α-methyl styrene) is associated with a different dependence of glass transition temperature on gas loading in calorimetric and rheological experiments. %0 journal article %@ 1463-9076 %A Oral, I.,Ott, F.,Abetz, V. %D 2022 %J Physical Chemistry Chemical Physics %N 19 %P 11687-11695 %R doi:10.1039/d2cp01076c %T Thermodynamic study of crown ether-lithium/magnesium complexes based on benz-1,4-dioxane and its homologues %U https://doi.org/10.1039/d2cp01076c 19 %X The synthesis and characterization of benz-1,4-dioxane crown ethers (CEs) and some of its homologues are described and analyzed. The effect of added C-atom within the CE ring (increasing the hydrophobicity of the CE ring by increasing the number of CH2-units) on the Li+ and Mg2+ complexation within a liquid–liquid extraction (LLE) is investigated and thermodynamically analyzed. The complex stability constant K, the change of entropy ∆S and enthalpy ∆H, and the Gibbs free energy ∆G are determined. The enhanced hydrophobicity of the CE ring results in stronger complexation stability of the Mg2+ complex, while the Li+ complexes are less favored. This effect mainly occurs due to the increased entropy term with improved hydrophobicity of the CE. These results indicate a stronger extraction of Li+ in Mg2+ -containing aqueous resources if more hydrophilic CEs are used. %0 journal article %@ 2077-0375 %A Kinfu, H.H.,Rahman, M.M.,Cevallos-Cueva, N.,Abetz, V. %D 2022 %J Membranes %N 12 %P 1216 %R doi:10.3390/membranes12121216 %T Mass Transport of Dye Solutions through Porous Membrane Containing Tannic Acid/Fe3+ Selective Layer %U https://doi.org/10.3390/membranes12121216 12 %X Tannic acid (TA)–Fe3+ membranes have received recent attention due to their sustainable method of fabrication, high water flux and organic solutes rejection performance. In this paper, we present a description of the transport of aqueous solutions of dyes through these membranes using the transport parameters of the Spiegler–Kedem–Katchalsky (SKK) model. The reflection coefficient (σ) and solute permeability (PS) of the considered TA–Fe3+ membranes were estimated from the non-linear model equations to predict the retention of solutes. The coefficients σ and PS depended on the porous medium and dye molecular size as well as the charge. The simulated rejections were in good agreement with the experimental findings. The model was further validated at low permeate fluxes as well as at various feed concentrations. Discrepancies between the observed and simulated data were observed at low fluxes and diluted feed solutions due to limitations of the SKK model. This work provides insights into the mass transport mechanism of dye solutions and allows the prediction of dye rejection by the TFC membranes containing a TA–Fe3+ selective layer using an SKK model. %0 journal article %@ 2053-1400 %A Mantel, T.,Glass, S.,Usman, M.,Lyberis, A.,Filiz, V.,Ernst, M. %D 2022 %J Environmental Science: Water Research & Technology %N 12 %P 2981-2993 %R doi:10.1039/D2EW00570K %T Adsorptive dead-end filtration for removal of Cr(vi) using novel amine modified polyacrylonitrile ultrafiltration membranes %U https://doi.org/10.1039/D2EW00570K 12 %X The present study investigates the concept of combining the processes of ultrafiltration (UF) and ion exchange into one single filtration step. By this, particulate matter and dissolved toxic hexavalent chromium (Cr(VI)) ions are removed by adsorptive dead-end filtration. For this purpose, we modified a conventional polyacrylonitrile (PAN) UF membrane with two methods to generate weak-base and strong-base anion exchanger functional groups on the membrane surface and in its pore structure. The pristine PAN membranes were chemically modified to generate primary (PAN-NH) and quaternary (PAN-Q) amine groups. Pristine PAN, PAN-NH and PAN-Q membranes were characterized and compared regarding their chemical and mechanical properties. The modified PAN membranes were tested in chromium filtration experiments at pH 5.5, pH 7 and pH 8.5. The fully loaded membranes were regenerated by caustic solution for desorption of the chromium. The effect of the membrane modifications on the pure water permeability, contact angle and BET surface was negligible. However, the charge of the membrane was affected significantly seen by the reversal of zeta potential from negative to positive values after modification. The filtration experiments revealed that the total adsorption capacities of PAN-NH and PAN-Q membranes are 151 mg and 145 mg Cr(VI) per m2 membrane surface after complete membrane saturation (cfeed = cpermeate), respectively. When compared with pristine PAN and PAN-Q membrane, the PAN-NH membrane has demonstrated high removal rates (>90%) for Cr(VI) in the first ten hours of filtration and thus more relevant for application-orientated membrane water treatment systems. Desorption of previously adsorbed Cr(VI) was achieved by filtering a regeneration solution (1 M NaCl and 0.01 M NaOH) through the loaded membranes. After regeneration, the adsorption capacity was almost completely recovered. The findings of this study verify that low-pressure amine-modified PAN membranes provide an effective and energy-efficient way to process Cr(VI) contaminated water for possible drinking water purposes. %0 journal article %@ 2073-4360 %A Raje, A.,Georgopanos, P.,Koll, J.,Lillepärg, J.,Handge, U.A.,Abetz, V. %D 2022 %J Polymers %N 1 %P 118 %R doi:10.3390/polym15010118 %T Open-Celled Foams from Polyethersulfone/Poly(Ethylene Glycol) Blends Using Foam Extrusion %U https://doi.org/10.3390/polym15010118 1 %X Polyethersulfone (PESU), as both a pristine polymer and a component of a blend, can be used to obtain highly porous foams through batch foaming. However, batch foaming is limited to a small scale and is a slow process. In our study, we used foam extrusion due to its capacity for large-scale continuous production and deployed carbon dioxide (CO2) and water as physical foaming agents. PESU is a high-temperature thermoplastic polymer that requires processing temperatures of at least 320 °C. To lower the processing temperature and obtain foams with higher porosity, we produced PESU/poly(ethylene glycol) (PEG) blends using material penetration. In this way, without the use of organic solvents or a compounding extruder, a partially miscible PESU/PEG blend was prepared. The thermal and rheological properties of homopolymers and blends were characterized and the CO2 sorption performance of selected blends was evaluated. By using these blends, we were able to significantly reduce the processing temperature required for the extrusion foaming process by approximately 100 °C without changing the duration of processing. This is a significant advancement that makes this process more energy-efficient and sustainable. Additionally, the effects of blend composition, nozzle temperature and foaming agent type were investigated, and we found that higher concentrations of PEG, lower nozzle temperatures, and a combination of CO2 and water as the foaming agent delivered high porosity. The optimum blend process settings provided foams with a porosity of approximately 51% and an average foam cell diameter of 5 µm, which is the lowest yet reported for extruded polymer foams according to the literature. %0 journal article %@ 2161-1653 %A Rangou, S.,Appold, M.,Lademann, B.,Buhr, K.,Filiz, V. %D 2022 %J ACS Macro Letters %N 9 %P 1142-1147 %R doi:10.1021/acsmacrolett.2c00352 %T Thermally and Chemically Stable Isoporous Block Copolymer Membranes %U https://doi.org/10.1021/acsmacrolett.2c00352 9 %X Ultrafiltration (UF) membranes, particularly membranes fabricated from self-assembled diblock copolymers, hold promise in wastewater treatment, dairy, and food industries. Membrane development goals involve combining a highly porous selective layer with a narrow pore size distribution with a mechanically stable supporting layer to achieve constant flux. To date, isoporous integral asymmetric membranes have been formed either as flat sheets or hollow fibers, and a surface-selective layer determines membrane separation performance. A unique isoporous membrane of the poly(4-vinylbenzocyclobutene)-b-poly(4-vinylpyridine) (PVBCB-b-P4VP) diblock copolymer with a substructure of almost homogeneous porosity throughout the body of the material (three-dimensional porosity) has been developed. Moreover, the matrix of the membrane (PVCB) enables it to undergo cross-linking, allowing the membrane to be thermally sterilized and applied in high-temperature UF applications. %0 journal article %@ 2077-0375 %A Kishore Chand, A.A.,Bajer, B.,Schneider, E.S.,Mantel, T.,Ernst, M.,Filiz, V.,Glass, S. %D 2022 %J Membranes %N 6 %P 580 %R doi:10.3390/membranes12060580 %T Modification of Polyacrylonitrile Ultrafiltration Membranes to Enhance the Adsorption of Cations and Anions %U https://doi.org/10.3390/membranes12060580 6 %X Ion adsorbing ultrafiltration membranes provide an interesting possibility to remove toxic ions from water. Furthermore, it is also possible to recover valuable elements. In this work, we demonstrate two easy strategies to modify polyacrylonitrile membranes with anion and cation adsorbing groups. The membranes were modified to have positively charged amine groups or negatively charged carboxyl groups. The success of the reactions was confirmed using IR spectroscopy and zeta-potential measurements. The membranes carrying negatively charged groups provided a negative zeta-potential and had an isoelectric point at pH 3.6, while the membranes carrying positively charged groups had a positive zeta-potential in the analyzed pH range. Since only the surface of the polymer was modified, the pore size and permeance of the membranes were not drastically affected. The membranes prepared by both modification strategies had a pure water permeance higher than 1000 L/(m2 h bar) and a water contact angle of 44.3 and 57.2°, respectively. Therefore, the membranes can be operated at low pressures with reasonable flux. Additionally, SEM images showed that the membranes were still open-pored. Adsorption tests using a positively and a negatively charged dye as well as a toxic cation and an anion were performed to analyze the adsorption behavior. Both membranes were able to adsorb the oppositely charged dyes as well as the copper and chromate ions. Therefore, these membranes are good candidates to purify water streams containing hazardous ions. %0 journal article %@ 1879-0003 %A Yakdoumi, F.Z.,Hadj-Hamou, A.S.,Rahoui, N.,Rahman, M.M.,Abetz, V. %D 2022 %J International Journal of Biological Macromolecules %N %P 55-69 %R doi:10.1016/j.ijbiomac.2022.05.142 %T Polylactic acid nanocomposites containing functionalized multiwalled carbon nanotubes as antimicrobial packaging materials %U https://doi.org/10.1016/j.ijbiomac.2022.05.142 %X Intended for food packaging, nanocomposites films based on poly (lactic acid) reinforced by polydopamine-wrapped carbon nanotubes (PLA/PDA-MWCNTs) or TiO2 modified PDA-MWCNTs (PLA/TiO2-PDA-MWCNTs) as nanofillers were elaborated via melt-blending and characterized by several techniques. The success of the synthesis of the modified MWCNTs was confirmed by transmission electron microscopy, Raman and Fourier transform infrared spectroscopies and thermogravimetric analysis. Properties such as slow crystallization rate, barrier, mechanical, antibacterial and antifungal properties, required for food packaging, have been investigated. As compared to a PLA pristine film, the PLA based modified MWCNTs at 3 wt% loading exhibited better properties, particularly the PLA/TiO2-PDA-MWCNTs nanocomposite film. Indeed, the crystallization rate increased about 10% for PLA/TiO2-PDA-MWCNTs and 7% for PLA/PDA-MWCNTs compared to the neat PLA. Besides, these improved results have positively impacted on the nanomechanical and barrier properties of PLA nanocomposites films. The Young modulus was increased by 161% for PLA/TiO2-PDA-MWCNTs and 113% for PLA/PDA-MWCNTs and the hardness was improved by 815% for PLA/TiO2-PDA-MWCNTs and 79% for PLA/PDA-MWCNTs, respectively, as compared to the pristine PLA. Furthermore, PLA based modified MWCNTs nanocomposite films displayed a strong antimicrobial and antifungal activity compared to pure PLA. %0 journal article %@ 1610-6199 %A Brinkmann, T.,Notzke, H.,Pohlmann, J.,Wolff, T.,Stecher, A.,Corner, A.,Gorringe, S. %D 2022 %J Cement International %N 1 %P 20-23 %T CO2 separation by membrane technology: Application in the cement industry based on pilot scale research %U 1 %X Membrane technology for CO2 separation is an established technology option in the oil and gas industry for many years now. The advent of novel membrane materials in combination with process design studies and pilot scale investigation proved the applicability for the separation of CO2 from flue gases. The trials concentrated mainly on the flue gas of coal fired power plants. Using the polymeric PolyActive™ thin film composite membranes developed by Hereon in two projects funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWi), long term operation in one- and two stage processes could be proven and CO2 enrichment to 95 mol-% could be demonstrated. Based on these results, the technology appears to be well suited for application in the cement industry. This potential as well as the experimental results in the power plant sector will be presented next to a short introduction to membrane technology. %0 journal article %@ 0024-9297 %A Dreyer, O.,Ibbeken, G.,Schneider, L.,Blagojevic, N.,Radjabian, M.,Abetz, V.,Müller, M. %D 2022 %J Macromolecules %N 17 %P 7564-7582 %R doi:10.1021/acs.macromol.2c00612 %T Simulation of Solvent Evaporation from a Diblock Copolymer Film: Orientation of the Cylindrical Mesophase %U https://doi.org/10.1021/acs.macromol.2c00612 17 %X Using particle-based Monte Carlo simulations and continuum modeling, we study the self-assembly of asymmetric diblock copolymers in the course of solvent evaporation. We examine the effects of evaporation rate and solvent selectivity on the structure formation, especially the alignment of the cylindrical domains of the minority block. The comparison of the two simulation techniques facilitates identifying general trends upon parameter variation, while their inherent differences help us to understand the role of single-chain dynamics, fluctuations, and additional model details. In both cases, the simulation models feature a liquid and a gas phase with an explicit surface, across which solvent evaporates. We propose a “layer evolution model” that links processing parameters to the final morphology via the time dependence of layers, in which characteristic microphases, for example, spherical or cylindrical, can form. The evolution of these layers varies with the processing conditions and determines the morphology. This allows us to discuss the interplay of various experimentally accessible parameters, which we support by respective simulations. Our results single out two main factors to ensure the formation of minority-block cylinders, perpendicular to the film surface: (i) Fast evaporation rates induce a steep gradient in the polymer-density profile; that is, the polymer density immediately beneath the gas–liquid surface rapidly exceeds the critical value for cylinder formation. This confines cylinder formation into a layer that is thinner than the actual cylinder diameter, forcing a perpendicular alignment. (ii) A certain selectivity of the gas phase for the matrix-forming, majority block is necessary to disrupt an otherwise entropically favored surface layer of the minority block that would lead to parallel cylinder alignment. %0 journal article %@ 2077-0375 %A Lillepärg, J.,Sperling, E.,Blanke, M.,Held, M.,Shishatskiy, S. %D 2021 %J Membranes %N 3 %P 174 %R doi:10.3390/membranes11030174 %T Multicomponent Network Formation in Selective Layer of Composite Membrane for CO2 Separation %U https://doi.org/10.3390/membranes11030174 3 %X As a promising material for CO2/N2 separation, PolyActiveTM can be used as a separation layer in thin-film composite membranes (TFCM). Prior studies focused on the modification of PolyActiveTM using low-molecular-weight additives. In this study, the effect of chemical crosslinking of reactive end-groups containing additives, forming networks within selective layers of the TFCM, has been studied. In order to understand the influence of a network embedded into a polymer matrix on the properties of the resulting materials, various characterization methods, including Fourier transform infrared spectroscopy (FTIR), gas transport measurements, differential scanning calorimetry (DSC) and atomic force microscopy (AFM), were used. The characterization of the resulting membrane regarding individual gas permeances by an in-house built “pressure increase” facility revealed a twofold increase in CO2 permeance, with insignificant losses in CO2/N2 selectivity. %0 journal article %@ 1022-1336 %A Rahman, M.,Abetz, V. %D 2021 %J Macromolecular Rapid Communications %N 13 %P 2100160 %R doi:10.1002/marc.202100160 %T Tailoring Crosslinked Polyether Networks for Separation of CO2 from Light Gases %U https://doi.org/10.1002/marc.202100160 13 %X Crosslinked poly(ethylene oxide) or poly(ethylene glycol) (PEG) is an ideal membrane material for separation of CO2 from light gases (e.g., H2, N2, O2, CH4 etc). In these membranes, crosslinking is used as a tool to suppress crystallinity of the PEG segments. In spite of the extensive effort to develop crosslinked PEG membranes in the last two decades, it remains a challenge to establish the structure–property relationships. This paper points out the fundamental limitations to correlate the chain topology of a network with the gas permeation mechanism. While a quantitative comparison of the molecular weight between crosslinks of networks and gas permeation mechanism reported by different research groups is challenging, effort is made to draw a qualitative picture. In this review, a focus is also put on the progress of utilization of dangling chain fractions to tailor the gas permeation behavior of PEG networks. %0 journal article %@ 2227-9717 %A Schuldt, K.,Brinkmann, T.,Georgopanos, P. %D 2021 %J Processes %N 5 %P 729 %R doi:10.3390/pr9050729 %T Zero-Discharge Process for Recycling of Tetrahydrofuran–Water Mixtures %U https://doi.org/10.3390/pr9050729 5 %X The sustainable design of separation and polymer synthesis processes is of great importance. Therefore, an energy-efficient process for the purification of tetrahydrofuran (THF)–water (H2O) solvent mixtures from an upstream polymer synthesis process in pilot scale was developed with the aim to obtain high purity separation products. The advantages and limitations of a hybrid process in the pilot scale were studied utilizing an Aspen Plus Dynamics® simulation at different pressures to prove the feasibility and energy efficiency. For the rough separation of the two components, distillation was chosen as the first process step. In this way, a separation of a water stream of sufficient quality for further precipitations after polymer synthesis could be achieved. In order to overcome the limitations of the distillation process posed by the azeotropic point of the mixture, a vapor permeation is used, which takes advantage of the heat of evaporation already used in the distillation column. For the purpose of achieving the required low water contents, an adsorption column is installed downstream for final THF purification. This leads to a novel hybrid separation process that is energy efficient and thus allows also the use of the solvents again for upstream polymer synthesis achieving the high purity requirements in a closed-loop process. %0 journal article %@ 0009-286X %A Schäfer, B.,Chacón, F.,Brinkmann, T.,Drews, A.,Jochem, E.,Sauer, J. %D 2021 %J Chemie - Ingenieur - Technik %N 8 %P 1247-1256 %R doi:10.1002/cite.202000251 %T Bewertung von Energieeffizienztechnologien mit der Methodik EDUAR&D an zwei Beispielen : Evaluation of Energy Efficiency Technologies with the EDUAR&D Method on Two Exemplary Technologies %U https://doi.org/10.1002/cite.202000251 8 %X Die Methodik EDUAR&D, kurz für Energiedaten und ‐analyse R&D, wird zur Bewertung von Energieeffizienztechniken genutzt. Es handelt sich um einen strukturierten Such‐ und Analyseprozess, der verschiedene methodische Ansätze zur Darstellung, Analyse und Bewertung der Techniken miteinander verbindet. Ziel ist es, Handlungsempfehlungen, z. B. bzgl. thematischer Schwerpunktsetzung, für die zukünftige Energieforschung im Rahmen der Forschungsförderung und für die Energiepolitik abzuleiten. Die Methodik wird hier am Beispiel der organophilen Nanofiltration und der Latentwärmespeicher vorgestellt. %0 journal article %@ 2073-4360 %A Thiessen, M.,Abetz, V. %D 2021 %J Polymers %N 8 %P 1189 %R doi:10.3390/polym13081189 %T Influence of the Glass Transition Temperature and the Density of Crosslinking Groups on the Reversibility of Diels-Alder Polymer Networks %U https://doi.org/10.3390/polym13081189 8 %X The interest in self-healing, recyclable, and adaptable polymers is growing. This work addresses the reversibility of crosslink formation based on Diels-Alder reaction in copolymer networks containing furfuryl and maleimide groups, which represent the “diene” and the “dienophile,” respectively. The copolymers are synthesized by atom transfer radical polymerization (ATRP) and free radical polymerization. The diene bearing copolymers are crosslinked either with a small molecule containing two dienophiles or with a dienophile bearing copolymer. The influence of the crosslinking temperature on the Diels-Alder reaction is analyzed. Furthermore, the influence of the glass transition temperature and the influence of the density of crosslinking groups on the thermo-reversibility of crosslinking are investigated by temperature dependent infrared spectroscopy and differential scanning calorimetry. It is shown that the reversibility of crosslinking is strongly influenced by the glass transition temperature of the system. %0 journal article %@ 1944-8244 %A Itzhak, T.,Segev-Mark, N.,Simon, A.,Abetz, V.,Ramon, G.,Segal-Peretz, T. %D 2021 %J ACS Applied Materials and Interfaces %N 13 %P 15591-15600 %R doi:10.1021/acsami.0c23084 %T Atomic Layer Deposition for Gradient Surface Modification and Controlled Hydrophilization of Ultrafiltration Polymer Membranes %U https://doi.org/10.1021/acsami.0c23084 13 %X In recent years, atomic layer deposition (ALD) has emerged as a powerful technique for polymeric membrane surface modification. In this research, we study Al2O3 growth via ALD on two polymeric phase-inverted membranes: polyacrylonitrile (PAN) and polyetherimide (PEI). We demonstrate that Al2O3 can easily be grown on both membranes with as little as 10 ALD cycles. We investigate the formation of Al2O3 layer gradient through the depth of the membranes using high-resolution transmission electron microscopy and elemental analysis, showing that at short exposure times, Al2O3 accumulates at the top of the membrane, reducing pore size and creating a strong growth gradient, while at long exposure time, more homogeneous growth occurs. This detailed characterization creates the knowledge necessary for controlling the deposition gradient and achieving an efficient growth with minimum pore clogging. By tuning the Al2O3 exposure time and cycles, we demonstrate control over the Al2O3 depth gradient and membranes’ pore size, hydrophilicity, and permeability. The oil antifouling performance of membranes is investigated using in situ confocal imaging during flow. This characterization technique reveals that Al2O3 surface modification reduces oil droplet surface coverage. %0 journal article %@ 1759-9954 %A Nieswandt, K.,Georgopanos, P.,Abetz, V. %D 2021 %J Polymer Chemistry %N 15 %P 2210-2221 %R doi:10.1039/D1PY00074H %T Well-defined polyvinylpyridine-block-polystyrene diblock copolymers via RAFT aqueous-alcoholic dispersion polymerization: synthesis and isoporous thin film morphology %U https://doi.org/10.1039/D1PY00074H 15 %X In this work, the synthesis and characterization of polyvinylpyridine-polystyrene (PVP-b-PS) diblock copolymers via reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization is presented. A series of poly(4-vinylpyridine) (P4VP) and poly(2-vinylpyridine) (P2VP) homopolymers were prepared by RAFT bulk polymerization at 80 °C using either a carboxylic acid functionalized trithiocarbonate or a non-functionalized trithiocarbonate RAFT agent. The P4VP and P2VP macroRAFT agents acted as stabilizers in the subsequent RAFT-mediated polymerization-induced self-assembly (PISA), when they were chain extended via RAFT aqueous-alcoholic dispersion polymerization of styrene at 70 °C. Following this protocol, high styrene conversions between 86–99% were achieved, leading to a series of well-defined, high molecular weight PVP-b-PS diblock copolymers with narrow molecular weight distributions as confirmed by proton nuclear magnetic resonance (1H NMR) spectroscopy and gel permeation chromatography (GPC). The bulk and surface morphologies of the diblock copolymers were investigated via transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The solution-cast and spin-coated thin films of the P4VP-b-PS and P2VP-b-PS diblock copolymers exhibited microphase-separated structures with spherical or cylindrical order according to their compositions. Spin-coated PVP-b-PS diblock copolymer films with weight fractions of the minority PVP block ranging from 17–24% were converted into porous surfaces by a controlled alignment and swelling strategy, exploiting the distinct selectivities of different solvents for the individual blocks. %0 journal article %@ 2569-3263 %A Abetz, V.,Brinkmann, T.,Sözbilir, M. %D 2021 %J Chemistry Teacher International %N 2 %P 141-154 %R doi:10.1515/cti-2020-0023 %T Fabrication and function of polymer membranes %U https://doi.org/10.1515/cti-2020-0023 2 %X The paper gives an introduction to membrane science and technology, an area of research of high significance for the development of a sustainable life for human beings. It is therefore intended to be a guide for teachers in the areas of chemistry, physics, or biology, who can incorporate the presented materials in their respective courses. The paper gives some insights into the different types of membranes, their functions, production and use in some selected areas. %0 journal article %@ 1022-1336 %A Oral, I.,Abetz, V. %D 2021 %J Macromolecular Rapid Communications %N 9 %P 2000746 %R doi:10.1002/marc.202000746 %T A Highly Selective Polymer Material using Benzo-9-Crown-3 for the Extraction of Lithium in Presence of Other Interfering Alkali Metal Ions %U https://doi.org/10.1002/marc.202000746 9 %X The recovery of lithium from global water resources continues to be challenging due to interfering metal ions with similar solution properties. Hence, a lithium‐selective diblock copolymer system containing crown ethers (CEs) is developed. A polystyrene‐block‐poly(methacrylic acid) diblock copolymer is synthesized first via a one‐pot solution–emulsion reversible addition–fragmentation chain transfer polymerization. A subsequent Steglich esterification yields the CE functionalized polymer. The complexation properties with different alkali metals are first investigated by liquid−liquid extraction (LLE) in dichloromethane (DCM) − water systems using free benzo‐9‐crown (B9C3), benzo‐12‐crown‐4 (B12C4), and benzo‐15‐crown‐5 (B15C5) CEs as reference components, followed by the correspondingly CE‐functionalized polymers. Extraction complexation constants in the aqueous phase are determined and the impact of the complexation constants on the extractability is estimated. The B9C3 CE is especially appealing since it has the smallest cavity size among all CEs. It is too small to complex sodium or potassium ions; however, it forms sandwich complexes with a lithium‐ion resulting in extraordinary complexation constants in polymer systems avoiding other interfering alkali metal ions. On this basis, a new material for the efficient extraction of lithium ion traces in global water resources is established. %0 journal article %@ 2637-403X %A Brennecke, F.,Clodt, J.,Pohlmann, J.,Abetz, C.,Brinkmann, T.,Abetz, V. %D 2021 %J Journal of Advanced Manufacturing and Processing %N 2 %P e10076 %R doi:10.1002/amp2.10076 %T Computational fluid dynamics simulation of the roll‐to‐roll coating process for the production of thin film composite membranes including validation %U https://doi.org/10.1002/amp2.10076 2 %X On the way towards a carbon‐neutral economy, a rise in the demand for separation technologies can be expected. This holds especially for membranes, which are energy efficient and thus very promising technologies. However, this challenges membrane researchers to consider the sustainability and scalability of their membrane fabrication processes. At our institute, we employ a roll‐to‐roll coating process for the production of thin film composite (TFC) membranes. This procedure is relatively easy to scale up and can be adapted for different polymers/solvents and thus applications. To increase the production efficiency and optimize the process for any polymer of interest, it is necessary to develop a solid understanding of the physics of this production system. Therefore, we would like to present a numerical model based on computational fluid dynamics (CFD) that can predict the film thickness of a polydimethylsiloxane (PDMS) based polymer coated in a roll‐to‐roll setup. In the future, this model should improve the production efficiency and fine‐tuning of process parameters. We verify the numerical procedure with a mesh refinement study and validate the predicted film thicknesses with experimental results for different roll speeds and polymer concentrations. The predicted variability of the thickness is assessed by a design of experiments study and compares relatively well to the measured variations of the coated membrane thickness. %0 journal article %@ 1862-8338 %A Kandelhard, F.,Schuldt, K.,Schymura, J.,Georgopanos, P.,Abetz, V. %D 2021 %J Macromolecular Reaction Engineering %N 4 %P 2000058 %R doi:10.1002/mren.202000058 %T Model-Assisted Optimization of RAFT Polymerization in Micro-Scale Reactors - A Fast Screening Approach %U https://doi.org/10.1002/mren.202000058 4 %X In this work, the combination of different modeling approaches with in‐line proton nuclear magnetic resonance (1H‐NMR) spectroscopy is used to assist the transfer of a reversible addition‐fragmentation chain transfer (RAFT) polymerization of methyl methacrylate to a micro‐scale reactor. This approach is then applied to find the optimal process parameters like temperature or residence time as well as the best composition of the reaction mixture in order to optimize the conversion and molecular characteristics of the synthesized polymer. A kinetic model based on ordinary differential equations implemented in the program Predici is first validated based on experimental data of reactions performed at various temperatures. Further on, two glass chip reactors and a coil reactor are used and combined in different ways to investigate the influence of the reactor geometry on the polymerization process. This optimization step is assisted by multiphysics modeling that focuses on the heat transfer properties of specific areas inside the reactors. This experimental setup is used successfully to carry out a stationary polymerization. This study shows that instationary experiments in a micro‐fluidic reactor system equipped with in‐line analytics allow for the fast development of a kinetic model for RAFT polymerizations. %0 journal article %@ 1022-1336 %A Xu, J.,Abetz, V. %D 2021 %J Macromolecular Rapid Communications %N 7 %P 2000648 %R doi:10.1002/marc.202000648 %T Nonionic UCST–LCST Diblock Copolymers with Tunable Thermoresponsiveness Synthesized via PhotoRAFT Polymerization %U https://doi.org/10.1002/marc.202000648 7 %X Nonionic double thermoresponsive diblock copolymers with both upper critical solution temperature (UCST) and lower critical solution temperature (LCST) phase transitions are synthesized via eco‐friendly photoiniferter reversible addition–fragmentation chain transfer polymerization. While the biocompatible random copolymer of di(ethylene glycol) methyl ether methacrylate and oligo(ethylene glycol) methacrylate accounts for the LCST transition, the block of polymethacrylamide from an easily accessible monomer with low health hazard is responsible for the UCST transition. Temperature‐dependent dynamic light scattering measurements confirm the formation of micellar aggregates in water at the temperatures below UCST‐ and above LCST‐type cloud points. Additionally, the temperature interval between UCST and LCST, where both blocks are dissolved, can be tailored by varying the comonomer ratio in the random copolymer block. With these unique advantages, the presented work introduces a new polymer system for the design of schizophrenic polymers. %0 journal article %@ 2168-0485 %A Aliyev, E.,Warfsmann, J.,Tokay, B.,Shishatskiy, S.,Lee, Y.,Lillepaerg, J.,Champness, N.,Filiz, V. %D 2021 %J ACS Sustainable Chemistry & Engineering %N 2 %P 684-694 %R doi:10.1021/acssuschemeng.0c06297 %T Gas Transport Properties of the Metal–Organic Framework (MOF)-Assisted Polymer of Intrinsic Microporosity (PIM-1) Thin-Film Composite Membranes %U https://doi.org/10.1021/acssuschemeng.0c06297 2 %X The current study summarizes the findings of single-gas transport performances of mixed matrix thin-film composite membranes consisting of metal–organic frameworks (MOFs) incorporated into a polymer of intrinsic microporosity (PIM-1). Mg-MOF-74, MIL-53, TIFSIX-3, and Zn2(bim)4 were investigated as stand-alone materials and as incorporated into the PIM-1 polymer matrix serving as a selective layer of thin-film composite membranes by various methods: Fourier-transform infrared spectroscopy, solid-state NMR, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The effect of MOF loading and nature on the mixed-matrix membrane morphology and operation were analyzed by varying the MOF content in the polymer matrix from 2 to 10 wt % with respect to the dry polymer weight. The results show that the incorporation of MOFs into the PIM-1 polymer matrix boosts the permeance and selectivity of H2 and O2 over N2, and the prepared PIM-1/TIFSIX_4 mixed matrix membrane shows better separation performance for CO2/CH4 than pure PIM-1. Such membranes can be good candidates for ammonia purge gas, oxygen enrichment, and acid gas treatment applications. %0 journal article %@ 0009-2665 %A Müller, M.,Abetz, V. %D 2021 %J Chemical Reviews %N 22 %P 14189-14231 %R doi:10.1021/acs.chemrev.1c00029 %T Nonequilibrium Processes in Polymer Membrane Formation: Theory and Experiment %U https://doi.org/10.1021/acs.chemrev.1c00029 22 %X Porous polymer and copolymer membranes are useful for ultrafiltration of functional macromolecules, colloids, and water purification. In particular, block copolymer membranes offer a bottom-up approach to form isoporous membranes. To optimize permeability, selectivity, longevity, and cost, and to rationally design fabrication processes, direct insights into the spatiotemporal structure evolution are necessary. Because of a multitude of nonequilibrium processes in polymer membrane formation, theoretical predictions via continuum models and particle simulations remain a challenge. We compiled experimental observations and theoretical approaches for homo- and block copolymer membranes prepared by nonsolvent-induced phase separation and highlight the interplay of multiple nonequilibrium processes—evaporation, solvent–nonsolvent exchange, diffusion, hydrodynamic flow, viscoelasticity, macro- and microphase separation, and dynamic arrest—that dictates the complex structure of the membrane on different scales. %0 journal article %@ 1022-1352 %A Semsarilar, M.,Abetz, V. %D 2021 %J Macromolecular Chemistry and Physics %N 1 %P 2000311 %R doi:10.1002/macp.202000311 %T Polymerizations by RAFT: Developments of the Technique and Its Application in the Synthesis of Tailored (Co)polymers %U https://doi.org/10.1002/macp.202000311 1 %X Reversible addition–fragmentation chain transfer (RAFT) polymerization is an increasingly popular method of controlled radical polymerization and remarkable advances is made in recent years. This polymerization technique offers great chances for more sustainable routes to obtain tailor‐made polymers with high precision. This article may be of interest not only for readers familiar with the technique, but also to newcomers to the field or colleagues, who are looking for more sustainable or safer polymerization techniques to obtain an extensive number of possible polymer structures. After an introduction to RAFT polymerization, different novel paths to carry out RAFT polymerization are discussed in terms of their potential and also advancements in the polymerization technology such as polymerization induced self‐assembly or carrying out the polymerization in continuous flow reactors are highlighted. At the end some upcoming application areas of polymers prepared by RAFT are presented. %0 journal article %@ 1022-1336 %A Rahman, M. %D 2021 %J Macromolecular Rapid Communications %N 16 %P 2100235 %R doi:10.1002/marc.202100235 %T Selective Swelling and Functionalization of Integral Asymmetric Isoporous Block Copolymer Membranes %U https://doi.org/10.1002/marc.202100235 16 %X SNIPS stands for a membrane fabrication technique that combines the evaporation induced self-assembly of the block copolymers and the classical nonsolvent induced phase separation. It is a one-step readily scalable technique to fabricate integral asymmetric isoporous membranes. The prominent developments in the last decade have carved out a niche for SNIPS as a potential technique to fabricate next generation isoporous membranes. In the last decade, a rich polymer library and variety of membrane postmodification routes have been successfully implemented to fabricate SNIPS membranes having the desired pore functionality. Some of these membranes form soft nanochannels in hydrated state due to swelling of the pore wall, i.e., the pore forming block of the block copolymer. These membranes having soft nanochannels have demonstrated the potential to perform several challenging separation tasks in ultrafiltration and nanofiltration. This paper highlights the currently accessible pore functionality, the strategies to tune the swelling of the soft nanochannels, the potential applications, and future perspectives of these membranes. %0 journal article %@ 2073-4360 %A Nieswandt, K.,Georgopanos, P.,Held, M.,Sperling, E.,Abetz, V. %D 2021 %J Polymers %N 1 %P 62 %R doi:10.3390/polym14010062 %T RAFT Emulsion Polymerization of Styrene Using a Poly((N,N-dimethyl acrylamide)-co-(N-isopropyl acrylamide)) mCTA: Synthesis and Thermosensitivity %U https://doi.org/10.3390/polym14010062 1 %X Thermoresponsive poly((N,N-dimethyl acrylamide)-co-(N-isopropyl acrylamide)) (P(DMA-co-NIPAM)) copolymers were synthesized via reversible addition−fragmentation chain transfer (RAFT) polymerization. The monomer reactivity ratios were determined by the Kelen–Tüdős method to be rNIPAM = 0.83 and rDMA = 1.10. The thermoresponsive properties of these copo-lymers with varying molecular weights were characterized by visual turbidimetry and dynamic light scattering (DLS). The copolymers showed a lower critical solution temperature (LCST) in water with a dependence on the molar fraction of DMA in the copolymer. Chaotropic and kosmotropic salt anions of the Hofmeister series, known to affect the LCST of thermoresponsive polymers, were used as additives in the aqueous copolymer solutions and their influence on the LCST was demonstrated. Further on, in order to investigate the thermoresponsive behavior of P(DMA-co-NIPAM) in a confined state, P(DMA-co-NIPAM)-b-PS diblock copolymers were prepared via polymerization induced self-assembly (PISA) through surfactant-free RAFT mediated emulsion polymerization of styrene using P(DMA-co-NIPAM) as the macromolecular chain transfer agent (mCTA) of the polymerization. As confirmed by cryogenic transmission electron microscopy (cryoTEM), this approach yielded stabilized spherical micelles in aqueous dispersions where the PS block formed the hydrophobic core and the P(DMA-co-NIPAM) block formed the hydrophilic corona of the spherical micelle. The temperature-dependent behavior of the LCST-type diblock copolymers was further studied by examining the collapse of the P(DMA-co-NIPAM) minor block of the P(DMA-co-NIPAM)-b-PS diblock copolymers as a function of temperature in aqueous solution. The nanospheres were found to be thermosensitive by changing their hydrodynamic radii almost linearly as a function of temperature between 25 °C and 45 °C. The addition of kosmotropic salt anions, as a potentially useful tuning feature of micellar assemblies, was found to increase the hydrodynamic radius of the micelles and resulted in a faster collapse of the micelle corona upon heating. %0 journal article %@ 2168-0485 %A Hamedi, H.,Brinkmann, T. %D 2021 %J ACS Sustainable Chemistry & Engineering %N 22 %P 7620-7629 %R doi:10.1021/acssuschemeng.1c01677 %T Rigorous and Customizable 1D Simulation Framework for Membrane Reactors to, in Principle, Enhance Synthetic Methanol Production %U https://doi.org/10.1021/acssuschemeng.1c01677 22 %X Power-to-liquid production via methanol synthesis has a high potential for emission reduction and carbon-neutral fuel production. However, the low equilibrium conversion of methanol synthesis via CO2 hydrogenation is identified as an important impediment in the further development of the technology. The latter necessitates a more innovative reactor design like membrane reactors to enhance the reaction conversion. In this article, a rigorous and customizable model for membrane reactors is developed using an equation-oriented flowsheet approach. The module requires no analytical correlations for thermodynamic properties, which often fail to reflect the system behavior accurately, or simplifying assumptions such as isobaric and isothermal operation conditions. The model was applied to the synthetic methanol production to determine to what extent a conceptual water-selective membrane reactor improves the reaction’s conversion and selectivity. We propose the process conditions at which a membrane reactor enhances these two key metrics, given the module’s heat transfer mode. This conceptual modeling serves as a guiding benchmark for future innovative reactor designs and facilitates the prospective process development and optimization due to the possible exportation and incorporation into the standard flowsheet simulators such as HYSYS or Aspen Plus. %0 journal article %@ 2073-4360 %A Eckert, T.,Klein, F.,Frieler, P.,Thunich, O.,Abetz, V. %D 2021 %J Polymers %N 18 %P 3147 %R doi:10.3390/polym13183147 %T Experimental Design in Polymer Chemistry - A Guide towards True Optimization of a RAFT Polymerization Using Design of Experiments (DoE) %U https://doi.org/10.3390/polym13183147 18 %X Despite the great potential of design of experiments (DoE) for efficiency and plannability in academic research, it remains a method predominantly used in industrial processes. From our perspective though, DoE additionally provides greater information gain than conventional experimentation approaches, even for more complex systems such as chemical reactions. Hence, this work presents a comprehensive DoE investigation on thermally initiated reversible addition–fragmentation chain transfer (RAFT) polymerization of methacrylamide (MAAm). To facilitate the adaptation of DoE for virtually every other polymerization, this work provides a step-by-step application guide emphasizing the biggest challenges along the way. Optimization of the RAFT system was achieved via response surface methodology utilizing a face-centered central composite design (FC-CCD). Highly accurate prediction models for the responses of monomer conversion, theoretical and apparent number averaged molecular weights, and dispersity are presented. The obtained equations not only facilitate thorough understanding of the observed system but also allow selection of synthetic targets for each individual response by prediction of the respective optimal factor settings. This work successfully demonstrates the great capability of DoE in academic research and aims to encourage fellow scientists to incorporate the technique into their repertoire of experimental strategies. %0 journal article %@ 2073-4360 %A Caliskan, E.,Shishatskiy, S.,Neumann, S.,Abetz, V.,Filiz, V. %D 2021 %J Polymers %N 1 %P 119 %R doi:10.3390/polym14010119 %T Investigation of the Side Chain Effect on Gas and Water Vapor Transport Properties of Anthracene-Maleimide Based Polymers of Intrinsic Microporosity %U https://doi.org/10.3390/polym14010119 1 %X In the present work, a set of anthracene maleimide monomers with different aliphatic side groups obtained by Diels Alder reactions were used as precursors for a series of polymers of intrinsic microporosity (PIM) based homo- and copolymers that were successfully synthesized and characterized. Polymers with different sizes and shapes of aliphatic side groups were characterized by size-exclusion chromatography (SEC), (nuclear magnetic resonance) 1H-NMR, thermogravimetric (TG) analysis coupled with Fourier-Transform-Infrared (FTIR) spectroscopy (TG-FTIR) and density measurements. The TG-FTIR measurement of the monomer-containing methyl side group revealed that the maleimide group decomposes prior to the anthracene backbone. Thermal treatment of homopolymer methyl-100 thick film was conducted to establish retro-Diels Alder rearrangement of the homopolymer. Gas and water vapor transport properties of homopolymers and copolymers were investigated by time-lag measurements. Homopolymers with bulky side groups (i-propyl-100 and t-butyl-100) experienced a strong impact of these side groups in fractional free volume (FFV) and penetrant permeability, compared to the homopolymers with linear alkyl side chains. The effect of anthracene maleimide derivatives with a variety of aliphatic side groups on water vapor transport is discussed. The maleimide moiety increased the water affinity of the homopolymers. Phenyl-100 exhibited a high water solubility, which is related to a higher amount of aromatic rings in the polymer. Copolymers (methyl-50 and t-butyl-50) showed higher CO2 and CH4 permeability compared to PIM-1. In summary, the introduction of bulky substituents increased free volume and permeability whilst the maleimide moiety enhanced the water vapor affinity of the polymers. %0 journal article %@ 1022-1344 %A Kargar, M.,Handge, U. %D 2021 %J Macromolecular Theory and Simulations %N 5 %P 2100016 %R doi:10.1002/mats.202100016 %T Numerical Simulations of Gas Sorption Experiments in Polymers: Influence of Aspect Ratio and Pressure Increase Rate on the Determination of Diffusion Coefficient %U https://doi.org/10.1002/mats.202100016 5 %X Diffusion and sorption phenomena of gases in polymers are of relevance for a number of technological applications, e.g., polymer foaming and membrane technology. The diffusion coefficient and the solubility, which depend on temperature and applied gas pressure, can be determined using the buoyancy method. In this work, the influence of two important parameters are investigated, i.e., the dimensions of the polymer sample and the pressure increase rate, on the accuracy of the determination of the diffusion coefficient D using gas sorption measurements. Numerical simulations on effectively two-dimensional diffusion phenomena in polymers are performed in order to obtain “ideal” experimental data. This set of “ideal” experimental data for polymer samples with specified geometrical dimensions is used for determination of the diffusion coefficient based on the analytical solution of Fickian diffusion in one spatial dimension. Different fitting procedures for determination of the diffusion coefficient are compared. Because of the finite time, which is necessary for pressure increase in a sorption experiment, the influence of pressure increase rate is also studied. This analysis reveals that an aspect ratio larger than 32 and a time for pressure increase smaller than approximately 3 × 10−9 m2D−1 is necessary for a reliable determination of diffusion coefficient D. %0 journal article %@ 2073-4360 %A Rahman, M. %D 2021 %J Polymers %N 23 %P 4181 %R doi:10.3390/polym13234181 %T Membrane Separation of Gaseous Hydrocarbons by Semicrystalline Multiblock Copolymers: Role of Cohesive Energy Density and Crystallites of the Polyether Block %U https://doi.org/10.3390/polym13234181 23 %X The energy-efficient separation of hydrocarbons is critically important for petrochemical industries. As polymeric membranes are ideal candidates for such separation, it is essential to explore the fundamental relationships between the hydrocarbon permeation mechanism and the physical properties of the polymers. In this study, the permeation mechanisms of methane, ethane, ethene, propane, propene and n-butane through three commercial multiblock copolymers PEBAX 2533, PolyActive1500PEGT77PBT23 and PolyActive4000PEGT77PBT23 are thoroughly investigated at 33 °C. This study aims to investigate the influence of cohesive energy density and crystallites of the polyether block of multiblock copolymers on hydrocarbon separation. The hydrocarbon separation behavior of the polymers is explained based on the solution–diffusion model, which is commonly accepted for gas permeation through nonporous polymeric membrane materials. %0 journal article %@ 0032-3861 %A Kravchenko, V.,Abetz, V.,Potemkin, I. %D 2021 %J Polymer %N %P 124288 %R doi:10.1016/j.polymer.2021.124288 %T Self-assembly of gradient copolymers in a selective solvent. New structures and comparison with diblock and statistical copolymers %U https://doi.org/10.1016/j.polymer.2021.124288 %X We perform comparative studies of self-assembly of equivalent statistical, diblock and gradient AB copolymers in a selective solvent using dissipative particle dynamics simulations. Both effects of the fraction of soluble and insoluble groups, selectivity of the solvent and degree of immiscibility of A and B groups on self-assembled structures are studied. With a simplified model of the statistical copolymer we predict macroscopic phase segregation, when non-aggregated chains coexist with precipitate. The later can be dense or swollen (physical gel) depending on degree of immiscibility of the A and B groups. For the case of diblock copolymer solutions, we predict thermodynamic stability of few structures: spherical and worm-like micelles, rings, vesicles and precipitate. We develop a simple theory, which allows calculating free energies of worms and rings (closed worms) and explaining transition between the structures. A number of diagrams of states is constructed. In case of gradient copolymers, two scenarios of self-assembly are predicted. The spherical micelles of gradient copolymer can aggregate with each other forming worms, rings and vesicles through aggregation of coronae (so-called sticky corona), which contain insoluble groups, if the fraction of insoluble groups per chain is not high. Herewith, the core of the assembled structures remains multidomain despite a high interfacial tension. The second (“diblock-like”) scenario is realized when the fraction of insoluble groups is high enough. In this case the core of worms, rings and vesicles is practically a monodomain, however, solvophilic groups can be intercalated into the core due to the primary structure of the copolymer. A new structure of a multi-compartment vesicle on the basis of gradient copolymers is predicted. %0 journal article %@ 2073-4360 %A Oral, I.,Grossmann, L.,Fedorenko, E.,Struck, J.,Abetz, V. %D 2021 %J Polymers %N 21 %P 3675 %R doi:10.3390/polym13213675 %T Synthesis of Poly(methacrylic acid)-block-Polystyrene Diblock Copolymers at High Solid Contents via RAFT Emulsion Polymerization %U https://doi.org/10.3390/polym13213675 21 %X The combination of polymerization–induced self-assembly (PISA) and reversible–addition fragmentation chain transfer (RAFT) emulsion polymerization offers a powerful technique to synthesize diblock copolymers and polymeric nanoparticles in a controlled manner. The RAFT emulsion diblock copolymerization of styrene and methacrylic acid (MAA) by using a trithiocarbonate as surfactant and RAFT agent was investigated. The Z-group of the RAFT agent was modified with a propyl-, butyl- and dodecyl- sidechain, increasing the hydrophobicity of the RAFT agent to offer well-controlled polymerization of poly(methacrylic acid)-block-polystyrene (PMAA-b-PS) diblock copolymers at high solid contents between 30–50 wt% in water. The kinetic data of the PMAA homopolymerization with the three different RAFT agents for various solvents was investigated as well as the RAFT emulsion polymerization of the diblock copolymers in pure water. While the polymerization of PMAA-b-PS with a propyl terminus as a Z-group suffered from slow polymerization rates at solid contents above 30 wt%, the polymerization with a dodecyl sidechain as a Z-group led to full conversion within 2 h, narrow molar mass distributions and all that at a remarkable solid content of up to 50 wt%. %0 journal article %@ 0011-2275 %A Hamedi, H. %D 2021 %J Cryogenics %N %P 103224 %R doi:10.1016/j.cryogenics.2020.103224 %T An innovative integrated process for helium and NGL recovery and nitrogen removal %U https://doi.org/10.1016/j.cryogenics.2020.103224 %X Raw natural gas is composed of several hydrocarbons, incombustible gases, such as nitrogen and helium, and impurities. While all the impurities are typically rejected at the beginning of the process, the removals of the two inert gases are postponed to last steps, where almost all the hydrocarbons except methane are already produced in an NGL recovery unit. Hence, NGL recovery, nitrogen removal and helium extraction steps are counted the most downstream units of the entire gas processing plant. This study investigates an integrated design and optimization of the three processes. In this paper, a novel process configuration, for co-production of sales gas, NGL and crude helium, is introduced. For this purpose, first we investigate and propose an efficient design to embed the helium extraction unit into a single-column nitrogen removal process. The proposed configuration is extended to an integrated process structure which combines nitrogen removal, NGL recovery and helium extraction units. The design reduces significantly the quantity of equipment as eliminating the need for the open refrigeration cycle and propane pre-cooling systems in NGL plants. High ethane and helium recovery, high nitrogen removal rate for different ranges of nitrogen, as well as the crude helium with high purity, are the outstanding potentials of the novel process. We finally optimize the key process parameters using the particle swarm optimization method to guarantee the minimum required work and present the economic evaluation of the new developed process. %0 journal article %@ 0935-9648 %A Zhang, Z.,Simon, A.,Abetz, C.,Held, M.,Höhme, A.,Schneider, E.,Segal-Peretz, T.,Abetz, V. %D 2021 %J Advanced Materials %N 48 %P 2105251 %R doi:10.1002/adma.202105251 %T Hybrid Organic–Inorganic–Organic Isoporous Membranes with Tunable Pore Sizes and Functionalities for Molecular Separation %U https://doi.org/10.1002/adma.202105251 48 %X Accomplishing on-demand molecular separation with a high selectivity and good permeability is very desirable for pollutant removal and chemical and pharmaceutical processing. The major challenge for sub-10 nm filtration of particles and molecules is the fabrication of high-performance membranes with tunable pore size and designed functionality. Here, a versatile top-down approach is demonstrated to produce such a membrane using isoporous block copolymer membranes with well-defined pore sizes combined with growth of metal oxide using sequential infiltration synthesis and atomic layer deposition (SIS and ALD). The pore size of the membranes is tuned by controlled metal oxide growth within and onto the polymer channels, enabling up to twofold pore diameter reduction. Following the growth, the distinct functionalities are readily incorporated along the membrane nanochannels with either hydrophobic, cationic, or anionic groups via straightforward and scalable gas/liquid–solid interface reactions. The hydrophilicity/hydrophobicity of the membrane nanochannel is significantly changed by the introduction of hydrophilic metal oxide and hydrophobic fluorinated groups. The functionalized membranes exhibit a superior selectivity and permeability in separating 1–2 nm organic molecules and fractionating similar-sized proteins based on size, charge, and hydrophobicity. This demonstrates the great potential of organic–inorganic–organic isoporous membranes for high-performance molecular separation in numerous applications. %0 journal article %@ 0033-4545 %A Zainal, N.,Ramli, H.,Fritz, M.,Abetz, V.,Chan, C. %D 2021 %J Pure and Applied Chemistry %N 10 %P 1119-1139 %R doi:10.1515/pac-2020-0904 %T Influence of thermal treatment on the properties and intermolecular interactions of epoxidized natural rubber-salt systems %U https://doi.org/10.1515/pac-2020-0904 10 %X The influence of thermal treatment on the thermal stability, thermal properties, dielectric properties and intermolecular interaction of binary epoxidized natural rubber (ENR)-salt systems, which may be a candidate for solid polymer electrolytes (SPEs) was investigated. Solubility of salt in ENR enhances, which may be due to the disruption of the lightly-crosslinked microgel under heat treatment. The increase in the ionic conductivities of the thermally treated ENR SPEs at constant salt content is correlated to the higher glass transition temperatures, development of percolation network and higher extent of intermolecular interactions between ENR and charged entities in this study. %0 journal article %@ 2168-0485 %A Vo, C.,Mondelli, C.,Hamedi, H.,Pérez-Ramírez, J.,Farooq, S.,Karimi, I. %D 2021 %J ACS Sustainable Chemistry & Engineering %N 31 %P 10591-10600 %R doi:10.1021/acssuschemeng.1c02805 %T Sustainability Assessment of Thermocatalytic Conversion of CO2 to Transportation Fuels, Methanol, and 1-Propanol %U https://doi.org/10.1021/acssuschemeng.1c02805 31 %X Using captured CO2 as a chemical feedstock is widely considered toward establishing low carbon technologies to mitigate climate change. Process systems engineering analyses can help increase the chances of success by identifying attractive targets at early stages. Here, a comparative techno-economic and environmental analysis of three thermocatalytic CO2-based plants individually producing liquid hydrocarbon transportation fuels (LHTF), methanol, and 1-propanol is introduced. While the 1-propanol plant generates a remarkable profit, the LHTF and methanol plants are not economically viable, mainly due to the CO2 and H2 input cost. Sensitivity analysis shows that the feedstock prices need to drop by 80% for these two plants to break even. A tax structure is not a sensible option since it would be more than 4 times the highest carbon tax currently implemented in the country. In terms of the environmental performance, the CO2 utilization efficiencies are 45.5, 60.1, and −33.8% for LHTF, methanol, and 1-propanol syntheses, respectively. The negative utilization efficiency in the 1-propanol plant highlights the need of a greener production of its raw material ethylene. When the entire life cycles of the products are considered, these emerging plants emit 85.9, 77.4, and 35.9% less CO2 than their conventional counterparts for the same output. Our study provides the first evaluation of CO2-based 1-propanol synthesis, highlighting its potential, underscores gaps in the CO2-based LHTF, methanol, and 1-propanol by comparing them on a uniform common basis, and sets future research directions. %0 journal article %@ 2077-0375 %A Hamedi, H.,Brinkmann, T.,Shishatskiy, S. %D 2021 %J Membranes %N 8 %P 596 %R doi:10.3390/membranes11080596 %T Membrane-Assisted Methanol Synthesis Processes and the Required Permselectivity %U https://doi.org/10.3390/membranes11080596 8 %X Water-selective membrane reactors are proposed in the literature to improve methanol yield for a standalone reactor. However, the methanol productivity is not a precise metric to show the system improvement since, with this approach, we do not consider the amount of energy loss through the undesirable co-permeation of H2, which could otherwise remain on the reaction side at high pressure. In other words, the effectiveness of this new technology should be evaluated at a process flowsheet level to assess its advantages and disadvantages on the overall system performance and, more importantly, to identify the minimum required properties of the membrane. Therefore, an equation-based model for a membrane reactor, developed in Aspen Custom Modeler, was incorporated within the process flowsheet of the methanol plant to develop an integrated process framework to conduct the investigation. We determined the upper limit of the power-saving at 32% by exploring the favorable conditions wherein a conceptual water selective membrane reactor proves more effective. Using these suboptimal conditions, we realized that the minimum required H2O/H2 selectivity is 190 and 970 based on the exergy analysis and overall power requirement, respectively. According to our results, the permselectivity of membranes synthesized for this application in the literature, showing improvements in the one-pass conversion, is well below the minimum requirement when the overall methanol synthesis process flowsheet comes into consideration. %0 journal article %@ 0888-5885 %A Kandelhard, F.,Georgopanos, P. %D 2021 %J Industrial & Engineering Chemistry Research %N 30 %P 11373-11384 %R doi:10.1021/acs.iecr.1c01319 %T Predici as a Polymer Engineers’ Tool for the Synthesis of Polymers via Anionic Polymerization %U https://doi.org/10.1021/acs.iecr.1c01319 30 %X In this study, the potential of a combined reaction kinetics model and a heat transfer model for the process development and scale-up of polystyrene synthesis via anionic polymerization, which is later extended to copolymerization with isoprene, is presented. In an innovative way, the program Predici was utilized to describe the requirements needed in the modeling of polymerization in a larger scale. This model combines the precise description of the polymerization reaction kinetics and the prediction of macromolecular properties offered by the program Predici with a heat transfer model to predict safety-relevant parameters such as the temperature and pressure profiles of the reaction system. In this way, it enables the precise investigation of interactions between process parameters and product properties as well as opens the path to optimal process control. Furthermore, changes associated with the scale-up of the process were studied using the model. The developed model was successfully applied to all of these tasks and could be used for fast screening in the development of polymer synthesis. %0 journal article %@ 0009-286X %A Glass, S.,Mantel, T.,Appold, M.,Sen, S.,Usman, M.,Ernst, M.,Filiz, V. %D 2021 %J Chemie - Ingenieur - Technik %N 9 %P 1396-1400 %R doi:10.1002/cite.202100037 %T Amine-Terminated PAN Membranes as Anion-Adsorber Materials %U https://doi.org/10.1002/cite.202100037 9 %X Anion-adsorbing membranes provide an interesting possibility to remove toxic arsenate and chromate from drinking water. A promising way to prepare anion-exchange materials is to introduce positively charged amine groups on polymers. In this study, polyacrylonitrile (PAN) ultrafiltration membranes were modified with amine functionalities on the membranes. The success of the modifications was demonstrated using infrared spectroscopy and zeta potential measurements. Additionally, the arsenate adsorption was analyzed. The modified membrane showed arsenate adsorption 5 times higher than the pristine PAN membrane. %0 journal article %@ 0009-286X %A Grünig, L.,Handge, U.,Koll, J.,Gronwald, O.,Weber, M.,Hankiewicz, B.,Scharnagl, N.,Abetz, V. %D 2021 %J Chemie - Ingenieur - Technik %N 9 %P 1451-1456 %R doi:10.1002/cite.202100034 %T Verbesserte Hydrophilie von Hohlfasermembranen mittels funktionalisierter Trennschicht für die Ultrafiltration : Dual Layer Hollow Fiber Membranes with Functionalized Separation Layer for Improved Hydrophilicity %U https://doi.org/10.1002/cite.202100034 9 %X Polyethersulfonbasierte Hohlfasermembranen mit einer hydrophil funktionalisierten Trennschicht wurden hergestellt und untersucht. In die Trennschicht wurde ein amphiphiles Triblockcopolymer mit verschiedenen Konzentrationen integriert. Um eine gesteigerte Hydrophilie und damit assoziiertes verringertes Fouling zu erreichen, bestehen die Blockcopolymere aus zwei äußeren Poly(ethylenoxid)-Blöcken. Diese flankieren den inneren Polyethersulfonblock, welcher der Verankerung des Additivs in die Membran dient. Gesteigerte Hydrophilie, gepaart mit Permeanzen von 2000 L m−2h−1bar−1 und einem Rückhalt von 100 kDa, kennzeichnete die vielversprechendste Membran dieser Studie. %0 journal article %@ 0024-9297 %A Grünig, L.,Meyer, A.,Emmler, T.,Abetz, V.,Handge, U. %D 2021 %J Macromolecules %N 10 %P 4816-4826 %R doi:10.1021/acs.macromol.1c00323 %T Solvent-Induced Crystallization of Poly(phenylene sulfone) %U https://doi.org/10.1021/acs.macromol.1c00323 10 %X Crystallization of poly(phenylene sulfone) (PPSU) occurs given that the solvent quality is low. This may be the case through adding a nonsolvent to a good solvent like N-methyl-2-pyrrolidone (NMP) or by choosing a poor solvent like N,N′-dimethylacetamide (DMAc) or N,N′-dimethylformamide (DMF). Wide-angle X-ray scattering (WAXS) investigations revealed the degree of crystallinity of PPSU in DMF and DMAc, and the lattice spacing for the structures was calculated to be 5.30 and 5.24 Å, respectively. Poly(phenylene sulfone) in DMAc formed well-defined banded spherulites with typical maltese crosses as observed by polarized light microscopy. For PPSU in DMF, crystalline plates were found by means of atomic force microscopy (AFM) with a thickness of 21 nm for a single plate. Both structures consist of lamellar fibrils with a thickness of 10 nm and a length in the order of 100–150 nm. The authors propose the reason for the crystallization to be π–π stacking of the rather stiff biphenylene groups. %0 journal article %@ 0376-7388 %A Wang, J.,Rahman, M.,Abetz, C.,Abetz, V. %D 2020 %J Journal of Membrane Science %N %P 118074 %R doi:10.1016/j.memsci.2020.118074 %T Bovine serum albumin selective integral asymmetric isoporous membrane %U https://doi.org/10.1016/j.memsci.2020.118074 %X Separation of bovine serum albumin (BSA) and hemoglobin (Hb), two proteins with almost identical molecular weight, has been a big challenge for more than two decades. Using traditional ultrafiltraion membranes separation of these proteins is possible only at the isoelectric point of one protein via electrostatic repulsion between the membrane and the other protein. Here we introduce an integral asymmetric isoporous membrane from polystyrene-block-poly(2-hydroxyethyl methacrylate-ran-2-(succinyloxy)ethyl methacrylate) (PS-b-P(HEMA-r-SEMA)) having random –OH and –COOH groups along the pore walls prepared by a method which combines solvent induced self-assembly of the block copolymer and nonsolvent induced phase separation (SNIPS). The membrane consists of soft isoporous channels due to swelling of the P(HEMA-r-SEMA) blocks in a hydrated state. The effective pore size of the membrane in a hydrated state is significantly lower compared to that in a dry state. These soft channels allow the permeation of BSA while retaining Hb at constant pH 7.4 where both proteins are negatively charged. In comparison to 22 commercial and in-house prepared membranes the PS-b-P(HEMA-r-SEMA) membrane presents unprecedented ideal selectivity of BSA over Hb (). Unlike the conventional technique in this case the electroneutrality of one protein is not mandatory which will provide significantly easier handling. %0 journal article %@ 2077-0375 %A Grünig, L.,Handge, U.A.,Koll, J.,Gronwald, O.,Weber, M.,Hankiewicz, B.,Scharnagl, N.,Abetz, V. %D 2020 %J Membranes %N 7 %P 143 %R doi:10.3390/membranes10070143 %T Hydrophilic Dual Layer Hollow Fiber Membranes for Ultrafiltration %U https://doi.org/10.3390/membranes10070143 7 %X In this study, a triblock copolymer was used as additive to fabricate new dual layer hollow fiber membranes with a hydrophilic active inner surface in order to improve their fouling resistance. The polymeric components of the solutions for membrane fabrication were poly(ether sulfone), poly(N-vinyl pyrrolidone), and the triblock copolymer. The additive consists of three blocks: a middle hydrophobic poly(ether sulfone) block and two outer hydrophilic alkyl poly(ethylene glycol) blocks. By varying the additive concentration in the solutions, it was possible to fabricate dual layer hollow fiber membranes that are characterized by a hydrophilic inner layer, a pure water permeance of over 1800 L/(m2 bar h) and a molecular weight cut-off of 100 kDa similar to commercial membranes. Contact angle and composition determination by XPS measurements revealed the hydrophilic character of the membranes, which improved with increasing additive concentration. Rheological, dynamic light scattering, transmission, and cloud point experiments elucidated the molecular interaction, precipitation, and spinning behavior of the solutions. The low-molecular weight additive reduces the solution viscosity and thus the average relaxation time. On the contrary, slow processes appear with increasing additive concentration in the scattering data. Furthermore, phase separation occurred at a lower non-solvent concentration and the precipitation time increased with increasing additive content. These effects revealed a coupling mechanism of the triblock copolymer with poly(N-vinyl pyrrolidone) in solution. The chosen process parameters as well as the additive solutions provide an easy and inexpensive way to create an antifouling protection layer in situ with established recipes of poly(ether sulfone) hollow fiber membranes. Therefore, the membranes are promising candidates for fast integration in the membrane industry. %0 journal article %@ 2077-0375 %A Sankhala, K.,Koll, J.,Abetz, V. %D 2020 %J Membranes %N 5 %P 83 %R doi:10.3390/membranes10050083 %T Facilitated Structure Formation in Isoporous Block Copolymer Membranes upon Controlled Evaporation by Gas Flow %U https://doi.org/10.3390/membranes10050083 5 %X The conventional fabrication of isoporous membranes via the evaporation-induced self-assembly of block copolymers in combination with non-solvent induced phase separation (SNIPS) is achieved under certain environmental conditions. In this study, we report a modification in the conventional fabrication process of (isoporous) flat sheet membranes in which the self-assembly of block copolymers is achieved by providing controlled evaporation conditions using gas flow and the process is introduced as gSNIPS. This fabrication approach can not only trigger and control the microphase separation but also provides isoporous structure formation in a much broader range of solution concentrations and casting parameters, as compared to fabrication under ambient, uncontrolled conditions. We systematically investigated the structure formation of the fabrication of integral asymmetric isoporous membranes by gSNIPS. A quantitative correlation between the evaporation conditions (causing solvent evaporation and temperature drop) and the self-assembly of block copolymers beginning from the top layer up to a certain depth, orientation of pores in the top layer and the substructure morphology has been discussed empirically. %0 journal article %@ 0959-8103 %A Handge, U.,Gronwald, O.,Weber, M.,Koll, J.,Abetz, C.,Hankiewicz, B.,Abetz, V. %D 2020 %J Polymer International %N 5 %P 502-512 %R doi:10.1002/pi.5984 %T Fabrication of membranes of polyethersulfone and poly(N‐vinyl pyrrolidone): influence of glycerol on processing and transport properties %U https://doi.org/10.1002/pi.5984 5 %X In this study, we focus on membranes of polyethersulfone and poly(N ‐vinyl pyrrolidone) and elucidate the influence of composition on the rheological, diffusion and precipitation properties of solutions which are used for membrane preparation via a non‐solvent‐induced phase separation process. The low‐molar‐mass component of the solution is a mixture of the solvent N ‐methyl‐2‐pyrrolidone and the non‐solvent glycerol. Cloud point, viscosity and diffusion measurements as well as precipitation experiments were performed in order to achieve a comprehensive understanding of the time dependence of the precipitation process. The addition of glycerol yields an increase of viscosity and a stronger tendency for demixing. The enhanced tendency for demixing causes a more rapid precipitation process. The average relaxation time of the solution as a function of glycerol concentration follows a similar trend to its viscosity. The increase of viscosity is associated with the increase of the monomeric friction coefficient. Two diffusive processes with clearly separated time scales appear in dynamic light scattering experiments in the presence of glycerol. This phenomenon is discussed taking into account the phase behaviour of the solution and the quality of the solvent. The addition of glycerol yields a lower pure water permeance whereas the molecular weight cut‐off is not altered in the ultrafiltration range. © 2020 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. %0 journal article %@ 2050-7488 %A Zhang, Z.,Rahman, M.,Abetz, C.,Abetz, V. %D 2020 %J Journal of Materials Chemistry A %N %P 9554-9566 %R doi:10.1039/d0ta01023e %T High-performance asymmetric isoporous nanocomposite membranes with chemically-tailored amphiphilic nanochannels %U https://doi.org/10.1039/d0ta01023e %X Tailoring the well-defined nanochannels of ultrafiltration membranes from self-assembled block copolymers (BCPs) toward the nanofiltration regime can expand their potential applications in the fractionation or separation of small molecules. One big issue is to fabricate a nanofiltration membrane with high permeance, good selectivity and excellent fouling resistance. Here such a membrane is presented using a tailor-made diblock copolymer composed of a hydrophobic major block and an amphiphilic minor block. A scalable integral asymmetric isoporous membrane is fabricated by the solvent evaporation induced co-assembly of BCP and in situ formed inorganic titanium dioxide nanoparticles combined with nonsolvent induced phase separation. The membrane nanopores are readily post-functionalized using negatively charged moieties by straightforward in situ gas–solid reactions. The potential to use the post-functionalized membrane for separation of small organic molecules having 1–2 nm lateral dimensions (having molecular weights in the range of 300–1500 g mol−1) is demonstrated. The negatively charged membrane displays high flux, excellent antifouling properties with a low permeation flux decline and nearly complete flux recovery. This type of membrane is a promising candidate for a new generation of nanofiltration membranes. %0 journal article %@ 1744-683X %A Bozorg, M.,Hankiewicz, B.,Abetz, V. %D 2020 %J Soft Matter %N %P 1066-1081 %R doi:10.1039/C9SM02032B %T Solubility behaviour of random and gradient copolymers of di- and oligo(ethylene oxide) methacrylate in water: effect of various additives %U https://doi.org/10.1039/C9SM02032B %X Poly[oligo(ethylene oxide)] based gradient and random copolymers with different compositions are synthesized via Cu-based atom transfer radical polymerization. The solubility behavior of these copolymers in pure water and in the presence of different salts, surfactants and ethanol is investigated. According to dynamic light scattering results, the lower critical solution temperature (LCST) depends on the structure of the copolymer and changes slightly by the additives. Good cosolvents like ethanol can increase the LCST through dissolving the collapsed copolymer chains to some extent. The same effect is observed for surfactants that make the copolymer solution more stable by preventing aggregation. Above a certain concentration of surfactant, depending on the copolymer structure, the solution is stable at all temperatures (no LCST). The effect of salts on the solubility of the copolymers is following the Hofmeister series and it is related linearly to the salt concentration. According to their affinity to the copolymer, the salts can increase or decrease the LCST. There is a considerable difference in phase transition changes for gradient or random copolymer after salt addition. While both copolymers show two-step phase transition in the presence of different salts, the changes of hydrodynamic radius and normalized scattering intensity is rather broad for random compared to gradient copolymer. Contrary as expected, varying the cations has no distinguishable effect on the LCST for both copolymers. All chlorides decrease the LCST. This decrease is almost the same for gradient copolymer and fluctuates for random copolymers. %0 journal article %@ 0079-6700 %A Radjabian, M.,Abetz, V. %D 2020 %J Progress in Polymer Science %N %P 101219 %R doi:10.1016/j.progpolymsci.2020.101219 %T Advanced porous polymer membranes from self-assembling block copolymers %U https://doi.org/10.1016/j.progpolymsci.2020.101219 %X The development of novel polymer membranes is a fascinating and challenging field in materials science and technology, as both the chemical composition and the processing have a big influence on the final properties of polymer membranes such as surface properties, pore structure and pore functionality. Progress in membrane-based separation processes like water and wastewater treatment, desalination and other separation applications depends on both a better understanding of the influence of the chemical composition of the membrane material and the membrane structure on the separation performance. In this review, first an overview of different types of polymer membranes and the separation mechanisms is given. Then the well-established fabrication of integral asymmetrically structured membranes by phase inversion methods in different geometries is presented before the more challenging combination of nonsolvent induced phase separation (NIPS) with block copolymer self-assembly is discussed. This leads to so-called integral asymmetric isoporous membranes composed of a thin selective surface layer with regular arranged and similar-sized pores on top of a thicker irregular, spongy sublayer. These membranes are the main focus of this review. So far, isoporous block copolymer membranes are still far from large scale production and commercial reality, however, they offer one of the most promising platforms for higher separation performance. They not only have potential in applications such as proteins separation, but can also become useful for the separation of small charged or uncharged molecules after appropriate post-functionalization of the pores. %0 journal article %@ 1869-5868 %A Abetz, V.,Chan, C.,Luscombe, C.,Matson, J.,Merna, J.,Nakano, T.,Raos, G.,Russell, G. %D 2020 %J Israel Journal of Chemistry %N 1 - 2 %P 9-19 %R doi:10.1002/ijch.201900182 %T Quo Vadis, Macromolecular Science? Reflections by the IUPAC Polymer Division on the Occasion of the Staudinger Centenary %U https://doi.org/10.1002/ijch.201900182 1 - 2 %X We survey the past, present and future of polymers and macromolecular science, both in general and giving specific examples from our diverse array of research backgrounds within polymer science and technology. As befitting our common bond, we pay some attention to the role of IUPAC. In line with this being part of a Rosarium philosophorum, one might say we conclude that it is Citius, Altius, Fortius for polymers in the century ahead, by which we mean “faster engagement, higher value, stronger properties”, and one should also add “longer usage”. In this way our broad community will continue to build on the century that has passed since Hermann Staudinger launched macromolecular science. %0 journal article %@ 1022-1336 %A Lauterbach, F.,Abetz, V. %D 2020 %J Macromolecular Rapid Communications %N 9 %P 2000029 %R doi:10.1002/marc.202000029 %T Continuous Kinetic Sampling of Flow Polymerizations via Inline UV–Vis Spectroscopy %U https://doi.org/10.1002/marc.202000029 9 %X Gapless monitoring of polymerization reactions is of paramount interest for academia and the polymer industry, allowing for efficient reaction screening and precise tailoring of the polymeric products. Herein, UV–visible spectroscopy (UV–vis) is employed as an operando measurement technique in continuous flow polymerization with ex situ calibration, to calculate monomer conversions with unprecedented resolution of only 10 s. A mathematical model based on volume contraction is provided for the first time, which yields monomer conversions from the absorption in the visible region for theoretically any homopolymerization. This model is validated for different monomers, solvents, and concentrations in a photoiniferter reversible addition‐fragmentation chain transfer polymerization, proving the versatility of the presented setup. Notably, an ultralow measurement volume of merely a few hundred nanoliters is enough to ensure high accuracy. %0 journal article %@ 1744-683X %A Lauterbach, F.,Abetz, V. %D 2020 %J Soft Matter %N 9 %P 2321-2331 %R doi:10.1039/C9SM02483B %T An eco-friendly pathway to thermosensitive micellar nanoobjects via photoRAFT PISA: the full guide to poly(N-acryloylpyrrolidin)-block-polystyrene diblock copolymers %U https://doi.org/10.1039/C9SM02483B 9 %X Spherical macromolecular assemblies, so-called latexes, consisting of polystyrene (PS) resemble a relevant class of synthetic polymers used for a plethora of applications ranging from coatings or lubricants to biomedical applications. Their synthesis is usually tailored to the respective application where emulsifiers, radical initiators, or other additives still play a major role in achieving the desired properties. Herein, we demonstrate an alternative based on the photoiniferter reversible addition–fragmentation chain transfer (RAFT) polymerization-induced self-assembly (PISA) of Poly(N-acryloylpyrrolidin)-block-polystyrene (PAPy-b-PS). This approach yields monodisperse nanospheres with tunable sizes based on an aqueous formulation with only two ingredients. These nanospheres are additionally thermosensitive, meaning that they change their hydrodynamic diameter linearly with the temperature in a broad range between 10 °C and 70 °C. Combined with the eco-friendly synthesis in pure water at 40 °C, the herein presented route constitutes an unprecedented pathway to thermosensitive diblock copolymer aggregates in short reaction times without any additives. %0 journal article %@ 0935-9648 %A Zhang, Z.,Rahman, M.,Abetz, C.,Höhme, A.,Sperling, E.,Abetz, V. %D 2020 %J Advanced Materials %N 8 %P 1907014 %R doi:10.1002/adma.201907014 %T Chemically Tailored Multifunctional Asymmetric Isoporous Triblock Terpolymer Membranes for Selective Transport %U https://doi.org/10.1002/adma.201907014 8 %X Membrane‐based separation of organic molecules with 1–2 nm lateral dimensions is a demanding but rather underdeveloped technology. The major challenge is to fabricate membranes having distinct nanochannels with desired functionality. Here, a bottom‐up strategy to produce such a membrane using a tailor‐made triblock terpolymer featuring miscible end blocks with two different functional groups is demonstrated. A scalable multifunctional integral asymmetric isoporous membrane is fabricated by the solvent evaporation‐induced self‐assembly of the block copolymer combined with nonsolvent‐induced phase separation. The membrane nanopores are readily functionalized using positively and negatively charged moieties by two straightforward gas–solid reactions. The pores of the post‐functionalized membranes act as target‐specific functional soft nanochannels due to swelling of the polyelectrolyte blocks in a hydrated state. The membranes show unprecedented separation selectivity of small molecules based on size and/or charge which demonstrates the potential of the proposed strategy to prepare next‐generation nanofiltration membranes. %0 journal article %@ 2073-4360 %A Saleem, S.,Rangou, S.,Abetz, C.,Filiz, V.,Abetz, V. %D 2020 %J Polymers %N 1 %P 41 %R doi:10.3390/polym12010041 %T Isoporous Membranes from Novel Polystyrene-b-poly(4-vinylpyridine)-b-poly(solketal methacrylate) (PS-b-P4VP-b-PSMA) Triblock Terpolymers and Their Post-Modification %U https://doi.org/10.3390/polym12010041 1 %X In this paper, the formation of nanostructured triblock terpolymer polystyrene-b-poly(4-vinylpyridine)-b-poly(solketal methacrylate) (PS-b-P4VP-b-PSMA), polystyrene-b-poly(4-vinylpyridine)-b-poly(glyceryl methacrylate) (PS-b-P4VP-b-PGMA) membranes via block copolymer self-assembly followed by non-solvent-induced phase separation (SNIPS) is demonstrated. An increase in the hydrophilicity was observed after treatment of non-charged isoporous membranes from PS-b-P4VP-b-PSMA, through acidic hydrolysis of the hydrophobic poly(solketal methacrylate) PSMA block into a hydrophilic poly(glyceryl methacrylate) PGMA block, which contains two neighbored hydroxyl (–OH) groups per repeating unit. For the first time, PS-b-P4VP-b-PSMA triblock terpolymers with varying compositions were successfully synthesized by sequential living anionic polymerization. Composite membranes of PS-b-P4VP-b-PSMA and PS-b-P4VP-b-PGMA triblock terpolymers with ordered hexagonally packed cylindrical pores were developed. The morphology of the membranes was studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM). PS-b-P4VP-b-PSMA triblock terpolymer membranes were further treated with acid (1 M HCl) to get polystyrene-b-poly(4-vinylpyridine)-b-poly(glyceryl methacrylate) (PS-b-P4VP-b-PGMA). Notably, the pristine porous membrane structure could be maintained even after acidic hydrolysis. It was found that membranes containing hydroxyl groups (PS-b-P4VP-b-PGMA) show a stable and higher water permeance than membranes without hydroxyl groups (PS-b-P4VP-b-PSMA), what is due to the increase in hydrophilicity. The membrane properties were analyzed further by contact angle, protein retention, and adsorption measurements. %0 journal article %@ 1383-5866 %A Gronwald, O.,Frost, I.,Ulbricht, M.,Kouchaki Shalmani, A.,Panglisch, S.,Grünig, L.,Handge, U.,Abetz, V.,Heijnen, M.,Weber, M. %D 2020 %J Separation and Purification Technology %N %P 117107 %R doi:10.1016/j.seppur.2020.117107 %T Hydrophilic poly(phenylene sulfone) membranes for ultrafiltration %U https://doi.org/10.1016/j.seppur.2020.117107 %X Poly(alkylene oxide) based tri- and multiblock oligomers with hydrophobic poly(phenylene sulfone) blocks were evaluated as dope solution additives used for preparation of improved poly(phenylene sulfone) (PPSU) flat sheet (FS) and single bore (SB) ultrafiltration membranes by non-solvent induced phase separation (NIPS). Identical polymer dope recipes were used in both of FS membrane preparation and SB fiber spinning processes. PPSU membranes modified with 9.2 wt % Pluronic® F127 based additive, M2 (7.5 kDa PPSU/ Pluronic® F127), or Lutensol® AT80 based additive, T2 (7.5 kDa PPSU/ Lutensol® AT80), displayed compared to pristine PPSU membranes elevated hydraulic permeance ranging from 485 to 674 kg m−2 bar-1h−1 (pristine PPSU: 310 – 464 kg m−2 bar-1h−1), higher molecular weight cut-off values from 37.0 to 53.5 kDa (pristine PPSU: 21.4 – 23.7 kDa), lower contact angles of 46.4° and 49.8° (pristine PPSU: 86.7°) and reduced fouling propensity with irreversible fouling values of 10 % (pristine PPSU: 15 %) for diluted potting soil extract as model substance. The combined analysis methods of X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance spectroscopy (1H NMR) indicated modest surface enrichment of the additives in the filtration layer. Consequently, PPSU ultrafiltration membranes modified with additives T2 and M2 provide interesting alternatives to poly(ether sulfone) (PESU) and poly(vinylidene fluoride) (PVDF) based membranes for surface water filtration combining both excellent filtration characteristics with a long lifetime due to its higher chemical resistance. %0 journal article %@ 1996-1944 %A Le, T.-T.,Pistidda, C.,Abetz, C.,Georgopanos, P.,Garroni, S.,Capurso, G.,Milanese, C.,Puszkiel, J.,Dornheim, M.,Abetz, V.,Klassen, T. %D 2020 %J Materials %N 4 %P 991 %R doi:10.3390/ma13040991 %T Enhanced Stability of Li-RHC Embedded in an Adaptive TPX™ Polymer Scaffold %U https://doi.org/10.3390/ma13040991 4 %X In this work, the possibility of creating a polymer-based adaptive scaffold for improving the hydrogen storage properties of the system 2LiH+MgB2+7.5(3TiCl3·AlCl3) was studied. Because of its chemical stability toward the hydrogen storage material, poly(4-methyl-1-pentene) or in-short TPXTM was chosen as the candidate for the scaffolding structure. The composite system was obtained after ball milling of 2LiH+MgB2+7.5(3TiCl3·AlCl3) and a solution of TPXTM in cyclohexane. The investigations carried out over the span of ten hydrogenation/de-hydrogenation cycles indicate that the material containing TPXTM possesses a higher degree of hydrogen storage stability. %0 journal article %@ 0033-4545 %A Bucknall, C.,Altstädt, V.,Auhl, D.,Buckley, P.,Dijkstra, D.,Galeski, A.,Gögelein, C.,Handge, U.,He, J.,Liu, C.,Michler, G.,Piorkowska, E.,Slouf, M.,Vittorias, I.,Wu, J. %D 2020 %J Pure and Applied Chemistry %N 9 %P 1521-1536 %R doi:10.1515/pac-2019-0408 %T Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 4: sporadic fatigue crack propagation %U https://doi.org/10.1515/pac-2019-0408 9 %X Fatigue tests were carried out on compression mouldings supplied by a leading polymer manufacturer. They were made from three batches of ultra-high molecular weight polyethylene (UHMWPE) with weight-average relative molar masses, ¯¯¯¯MW, of about 0.6 × 106, 5 × 106 and 9 × 106. In 10 mm thick compact tension specimens, crack propagation was so erratic that it was impossible to follow standard procedure, where crack-tip stress intensity amplitude, ΔK, is raised incrementally, and the resulting crack propagation rate, da/dN, increases, following the Paris equation, where a is crack length and N is number of cycles. Instead, most of the tests were conducted at fixed high values of ΔK. Typically, da/dN then started at a high level, but decreased irregularly during the test. Micrographs of fracture surfaces showed that crack propagation was sporadic in these specimens. In one test, at ΔK = 2.3 MPa m0.5, there were crack-arrest marks at intervals Δa of about 2 μm, while the number of cycles between individual growth steps increased from 1 to more than 1000 and the fracture surface showed increasing evidence of plastic deformation. It is concluded that sporadic crack propagation was caused by energy-dissipating crazing, which was initiated close to the crack tip under plane strain conditions in mouldings that were not fully consolidated. By contrast, fatigue crack propagation in 4 mm thick specimens followed the Paris equation approximately. The results from all four reports on this project are reviewed, and the possibility of using fatigue testing as a quality assurance procedure for melt-processed UHMWPE is discussed. %0 journal article %@ 1022-1336 %A Haida, P.,Abetz, V. %D 2020 %J Macromolecular Rapid Communications %N 16 %P 2000273 %R doi:10.1002/marc.202000273 %T Acid‐Mediated Autocatalysis in Vinylogous Urethane Vitrimers %U https://doi.org/10.1002/marc.202000273 16 %X Vitrimers are a class of polymeric materials with outstanding properties. Intramolecular substitution reactions lead to a dynamic exchange within the polymer network which enables thermoreversible stress relaxation in yet permanently crosslinked materials. In this paper, the acid‐mediated autocatalysis is explored as a rearrangement pathway for vinylogous urethane vitrimers. The autocatalysis enables transimination reactions, resulting in a dynamic exchange among the enamine‐one species, without an excess of free amines. Therefore, the enamine‐ones are protonated by a Brønsted acid and turn into electrophilic iminium‐ones, thus enabling fast backward and substitution reactions with water and free amines. This work provides an in‐depth investigation of the mechanism by kinetic studies of selected compounds. In addition, novel elastomeric and thermosetting poly(vinylogous urethane) networks with and without free amine groups and additional para‐toluene sulfonic acid as a Brønsted catalyst are prepared by bulk polymerization of hexane‐1,6‐diylbis(3‐oxobutanoate) and tris(2‐aminoethyl)amine. The underlying exchange mechanisms are determined by stress‐relaxation experiments with stress relaxation times of 0.3–54 000 s at 110 °C. %0 journal article %@ 2642-4169 %A Eckert, T.,Abetz, V. %D 2020 %J Journal of Polymer Science %N 21 %P 3050-3060 %R doi:10.1002/pol.20200566 %T Polymethacrylamide—An underrated and easily accessible upper critical solution temperature polymer: Green synthesis via photoiniferter reversible addition–fragmentation chain transfer polymerization and analysis of solution behavior in water/ethanol mixtures %U https://doi.org/10.1002/pol.20200566 21 %X Within the group of stimuli‐responsive, “smart” materials, upper critical solution temperature (UCST) polymers remain sparsely investigated. Thus, this work focusses on a vastly ignored UCST polymer: polymethacrylamide (PMAAm). A cost‐efficient photoiniferter reversible addition–fragmentation chain transfer (RAFT) polymerization yielding narrowly dispersed (Đ < 1.1) PMAAm is presented. This PMAAm exhibits highly thermoreversible UCST‐type phase transitions (PT) in water/ethanol mixtures (ethanol content: 17–35 wt%) which are investigated via temperature dependent dynamic light scattering (DLS). Apart from the ethanol content, the PT temperature is affected by polymer mass fraction and chain length and varies between 10–80 °C depending on the three mentioned parameters. Lastly, PMAAm's propensity towards amide hydrolysis and concomitant PT‐suppression is investigated. Below temperatures of 40 °C, PMAAm solutions show no sign of amide hydrolysis for at least three days, however, if heated to 70 °C, the thermoresponsiveness gradually degrades within hours. %0 journal article %@ 1420-3049 %A Rangou, S.,Moschovas, D.,Moutsios, I.,Manesi, G.,Tsitoni, K.,Bovsunovskaya, P.,Ivanov, D.,Thomas, E.,Avgeropoulos, A. %D 2020 %J Molecules %N 24 %P 6030 %R doi:10.3390/molecules25246030 %T Dendrons and Dendritic Terpolymers: Synthesis, Characterization and Self-Assembly Comparison %U https://doi.org/10.3390/molecules25246030 24 %X To the best of our knowledge, this is the very first time that a thorough study of the synthetic procedures, molecular and thermal characterization, followed by structure/properties relationship for symmetric and non-symmetric second generation (2-G) dendritic terpolymers is reported. Actually, the synthesis of the non-symmetric materials is reported for the first time in the literature. Anionic polymerization enables the synthesis of well-defined polymers that, despite the architecture complexity, absolute control over the average molecular weight, as well as block composition, is achieved. The dendritic type macromolecular architecture affects the microphase separation, because different morphologies are obtained, which do not exhibit long range order, and various defects or dislocations are evident attributed to the increased number of junction points of the final material despite the satisfactory thermal annealing at temperatures above the highest glass transition temperature of all blocks. For comparison reasons, the initial dendrons (miktoarm star terpolymer precursors) which are connected to each other in order to synthesize the final dendritic terpolymers are characterized in solution and in bulk and their self-assembly is also studied. A major conclusion is that specific structures are adopted which depend on the type of the core connection between the ligand and the active sites of the dendrons. %0 journal article %@ 0376-7388 %A Wang, J.,Rahman, M.,Abetz, C.,Abetz, V. %D 2020 %J Journal of Membrane Science %N %P 118535 %R doi:10.1016/j.memsci.2020.118535 %T Tuning the size selectivity of isoporous membranes for protein fractionation via two scalable post treatment approaches %U https://doi.org/10.1016/j.memsci.2020.118535 %X The molecular design of block copolymer membranes has been widely used as a toolbox to explore the functionality and pore size of the membranes. However, the study of membrane performance as a function of systematic change of the pore size has not been widely explored so far. We prepared an integral asymmetric isoporous membrane on the example of polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) membranes using an easily scalable method which combines the block copolymer self-assembly and nonsolvent induced phase separation. The pore size of the PS-b-PHEMA membrane was tuned via two post treatment methods, a chemical postmodification by urethane chemistry and a physical post treatment by thermal annealing, respectively. At pH 7.4 bovine serum albumin (BSA), hemoglobin (Hb) and catalase (Cat) do not adsorb on the prepared membranes. The retention of BSA, Hb and Cat from their aqueous solution was investigated and the ideal selectivities of three protein pairs , and were calculated. The and of the postmodified membranes were significantly higher than those of the PS-b-PHEMA membrane. This study is the first to demonstrate that the size selectivity of a SNIPS membrane can be enhanced by controlled physical and chemical post treatment of a SNIPS membrane. %0 journal article %@ 2073-4360 %A Polevaya, V.,Vorobei, A.,Gavrikov, A.,Matson, S.,Parenago, O.,Shishatskiy, S.,Khotimskiy, V. %D 2020 %J Polymers %N 11 %P 2468 %R doi:10.3390/polym12112468 %T Modification of Poly(4-methyl-2-pentyne) in the Supercritical Fluid Medium for Selective Membrane Separation of CO2 from Various Gas Mixtures %U https://doi.org/10.3390/polym12112468 11 %X The modification of highly permeable films of brominated 1,2-disubstituted polyacetylene, poly(4-methyl-2-penthyne), via incorporation of in situ formed butylimidazolium bromide is reported for the first time. Principal possibility and efficiency of supercritical CO2 and CHF3 use as reaction media for the corresponding process, namely for quaternization of butylimidazole by brominated polymer are revealed. As a result, we prepared new membrane materials possessing promising properties such as stability toward organic solvents, good mechanical properties and significantly improved CO2-selectivity while maintaining gas permeability at high values. Comparative analysis of the results allowed us to determine content and conditions for the incorporation of butylimidazolium groups optimal for most efficient separation of CO2 from industrial gas mixtures. These results are of interest for the designing of new CO2 selective membranes. %0 journal article %@ 1996-1944 %A Gloeckle, C.,Konkol, T.,Jacobs, O.,Limberg, W.,Ebel, T.,Handge, U. %D 2020 %J Materials %N 19 %P 4413 %R doi:10.3390/ma13194413 %T Processing of Highly Filled Polymer–Metal Feedstocks for Fused Filament Fabrication and the Production of Metallic Implants %U https://doi.org/10.3390/ma13194413 19 %X Fused filament fabrication (FFF) is a new procedure for the production of plastic parts, particularly if the parts have a complex geometry and are only needed in a limited quantity, e.g., in specific medical applications. In addition to the production of parts which are purely composed of polymers, fused filament fabrication can be successfully applied for the preparation of green bodies for sintering of metallic implant materials in medical applications. In this case, highly filled polymer–metal feedstocks, which contain a variety of polymeric components, are used. In this study, we focus on various polymer-metal feedstocks, investigate the rheological properties of these materials, and relate them to our results of FFF experiments. Small amplitudes of shear oscillations reveal that the linear range of the polymer–metal feedstocks under investigation is very small, which is caused by elastic and viscous interactions between the metallic particles. These interactions strongly influence or even dominate the flow properties of the feedstock depending on the applied shear stress. The magnitude of the complex viscosity strongly increases with decreasing angular frequency, which indicates the existence of an apparent yield stress. The viscosity increase caused by the high powder loading needed for sintering limits the maximum printing velocity and the minimum layer height. The apparent yield stress hinders the formation of smooth surfaces in the FFF process and slows down the welding of deposited layers. The influence of composition on the processing parameters (suitable temperature range) and part properties (e.g., surface roughness) is discussed on the basis of rheological data. %0 journal article %@ 2077-0375 %A Bucher, T.,Clodt, J.,Abetz, C.,Bajer, B.,Filiz, V. %D 2020 %J Membranes %N 12 %P 404 %R doi:10.3390/membranes10120404 %T Spraying of Ultrathin Isoporous Block Copolymer Membranes—A Story about Challenges and Limitations %U https://doi.org/10.3390/membranes10120404 12 %X Isoporous membranes can be prepared by a combination of self-assembly of amphiphilic block copolymers and the non-solvent induced phase separation process. As the general doctor-blade technique suffers from high consumption of expensive block copolymer, other methods to reduce its concentration in the casting solution are sought after. Decreasing the block copolymer concentration during membrane casting and applying the block copolymer solution on a support membrane to obtain ultrathin isoporous membrane layers with e.g., spraying techniques, can be an answer. In this work we focused on the question if upscaling of thin block copolymer membranes produced by spraying techniques is feasible. To upscale the spray coating process, three different approaches were pursued, namely air-brush, 1-fluid nozzles and 2-fluid nozzles as generally used in the coating industry. The different spraying systems were implemented successfully in a membrane casting machine. Thinking about future development of isoporous block copolymer membranes in application it was significant that a continuous preparation process can be realised combining spraying of thin layers and immersion of the thin block copolymer layers in water to ensure phase-separation. The system was tested using a solution of polystyrene-block-poly(4-vinylpyridine) diblock copolymer. A detailed examination of the spray pattern and its homogeneity was carried out. The limitations of this method are discussed. %0 journal article %@ 0033-4545 %A Bucknall, C.,Altstädt, V.,Auhl, D.,Buckley, P.,Dijkstra, D.,Galeski, A.,Gögelein, C.,Handge, U.,He, J.,Liu, C.,Michler, G.,Piorkowska, E.,Slouf, M.,Vittorias, I.,Wu, J. %D 2020 %J Pure and Applied Chemistry %N 9 %P 1503-1519 %R doi:10.1515/pac-2019-0406 %T Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 3: deformation, wear and fracture %U https://doi.org/10.1515/pac-2019-0406 9 %X Three grades of polyethylene, with weight-average relative molar masses, ¯¯¯¯MW, of approximately 0.6 × 106, 5 × 106, and 9 × 106, were supplied as compression mouldings by a leading manufacturer of ultra-high molecular weight polyethylene (UHMWPE). They were code-named PE06, PE5, and PE9, respectively. Specimens cut from these mouldings were subjected to a wide range of mechanical tests at 23 °C. In tensile tests, deformation was initially elastic and dominated by crystallinity, which was highest in PE06. Beyond the yield point, entanglement density became the dominant factor, and at 40 % strain, the rising stress–strain curves for PE5 and PE9 crossed the falling PE06 curve. Fracture occurred at strains above 150 %. Differences in stress–strain behaviour between PE5 and PE9 were relatively small. A similar pattern of behaviour was observed in wear tests; wear resistance showed a marked increase when ¯¯¯¯MW was raised from 0.6 × 106 to 5 × 106, but there was no further increase when it was raised to 9 × 106. It is concluded that the unexpected similarity in behaviour between PE5 and PE9 was due to incomplete consolidation during moulding, which led to deficiencies in entanglement at grain boundaries; they were clearly visible on the surfaces of both tensile and wear specimens. Fatigue crack growth in 10 mm thick specimens was so severely affected by inadequate consolidation that it forms the basis for a separate report – Part 4 in this series. %0 journal article %@ 0033-4545 %A Bucknall, C.,Altstädt, V.,Auhl, D.,Buckley, P.,Dijkstra, D.,Galeski, A.,Gögelein, C.,Handge, U.,He, J.,Liu, C.,Michler, G.,Piorkowska, E.,Slouf, M.,Vittorias, I.,Wu, J. %D 2020 %J Pure and Applied Chemistry %N 9 %P 1469-1483 %R doi:10.1515/pac-2019-0405 %T Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 1: characterizing molecular weight %U https://doi.org/10.1515/pac-2019-0405 9 %X This is the first of four reports from IUPAC Sub-Committee 4.2.1: Structure and Properties of Commercial Polymers, which in 2010 set up a Task Group to evaluate the effectiveness of available methods of quality control (QC) and quality assurance (QA) of ultra-high molecular weight polyethylene (UHMWPE) mouldings and to find improvements where possible. This was seen as an important investigation, because prosthetic hip and knee joints are among the most demanding applications of synthetic polymers and UHMWPE is the polymer of choice for this purpose: it is biocompatible, durable, and has robust mechanical properties. In this context, the term ‘ultra-high’ indicates a weight average relative molar mass, ¯¯¯¯Mw, greater than 106. In practice, the minimum ¯¯¯¯Mw for orthopaedic grades of polyethylene (PE) is about 5 × 106, which for linear PE means that chains have a contour length of at least 45 μm. The authors note that the more familiar and historical name of relative molecular mass is ‘molecular weight’, which features in the title of this series of reports. That name will be used throughout this series, except where numerical values are involved. Because it is impossible to process materials with such large molecules using conventional injection moulding or screw extrusion, reactor powder (fine particulate material obtained directly from the polymerization plant) is usually either ram-extruded or compression moulded under elevated pressure over extended periods of time to allow adequate levels of reptation to take place across inter-particle boundaries. Relaxation times can be reduced by raising processing temperatures, but this option has strict limits. Thermally induced chain scission must be avoided as much as possible. A related problem is that high pressures raise melting points and therefore narrow the processing window. The effect of temperature on relaxation times is less pronounced in PE than it is in other thermoplastics, because of its high crystallinity and low glass transition temperature Tg. %0 journal article %@ 0033-4545 %A Bucknall, C.,Altstädt, V.,Auhl, D.,Buckley, P.,Dijkstra, D.,Galeski, A.,Gögelein, C.,Handge, U.,He, J.,Liu, C.,Michler, G.,Piorkowska, E.,Slouf, M.,Vittorias, I.,Wu, J. %D 2020 %J Pure and Applied Chemistry %N 9 %P 1485-1501 %R doi:10.1515/pac-2019-0403 %T Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 2: crystallinity and supra molecular structure %U https://doi.org/10.1515/pac-2019-0403 9 %X Test methods including OM, SEM, TEM, DSC, SAXS, WAXS, and IR were used to characterise supra-molecular structure in three batches of polyethylene (PE), which had weight-average relative molar masses ¯¯¯¯Mw of approximately 0.6 × 106, 5 × 106, and 9 × 106. They were applied to compression mouldings made by the polymer manufacturer. Electron microscopy showed that powders formed in the polymerization reactor consisted of irregularly shaped grains between 50 and 250 μm in diameter. Higher magnification revealed that each grain was an aggregate, composed of particles between 0.4 and 0.8 μm in diameter, which were connected by long, thin fibrils. In compression mouldings, lamellar thicknesses ranged from 7 to 23 nm. Crystallinity varied between 70 and 75 % in reactor powder, but was lower in compression mouldings. Melting peak temperatures ranged from 138 to 145 °C, depending on processing history. DMTA showed that the glass transition temperature θ g was −120 °C for all three grades of polyethylene. IR spectroscopy found negligibly small levels of oxidation and thermal degradation in mouldings. Optical microscopy revealed the presence of visible fusion defects at grain boundaries. It is concluded that relatively weak defects can be characterized using optical microscopy, but there is a need for improved methods that can detect less obvious fusion defects. %0 journal article %@ 2196-7350 %A Aliyev, E.,Shishatskiy, S.,Abetz, C.,Lee, Y.,Neumann, S.,Emmler, T.,Filiz, V. %D 2020 %J Advanced Materials Interfaces %N 19 %P 2000443 %R doi:10.1002/admi.202000443 %T SI‐ATRP Polymer‐Functionalized Graphene Oxide for Water Vapor Separation %U https://doi.org/10.1002/admi.202000443 19 %X Graphene oxide is functionalized with poly(2‐diethylaminoethyl) methacrylate (PDEAEMA), and the resulting material is used as a selective layer of a thin‐film composite membrane (TFCM). The polymer synthesis is carried out by surface‐initiated atom transfer radical polymerization (SI‐ATRP) from bulk and also from single‐layer graphene oxide (GO). The polymer brushes synthesized by the “grafting from” method are characterized by size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR), Fourier‐transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), and TGA‐FTIR. The TFCMs are prepared by the deposition of the selective layer from a stable polymer solution. The molecular weight of the polymer is sufficiently high to obtain a continuous defect‐free layer on a porous support. The thickness of the selective layer is ≈400 nm, as found in morphological investigations by scanning electron microscopy (SEM). The obtained membranes are utilized for gas and water vapor transport experiments in a wide temperature range. The water vapor permeability coefficient of the investigated materials is up to 4500 Barrer; this value increases threefold upon quaterization of the amine. The high permeance and selectivity for water vapor make this type of thin‐film membranes a potential candidate for membrane distillation. %0 journal article %@ 0009-286X %A Brinkmann, T.,Notzke, H.,Wolff, T.,Zhao, L.,Luhr, S.,Stolten, D. %D 2019 %J Chemie - Ingenieur - Technik %N 1-2 %P 30-37 %R doi:10.1002/cite.201800083 %T Characterization of a New Flat Sheet Membrane Module Type for Gas Permeation %U https://doi.org/10.1002/cite.201800083 1-2 %X Modern high‐performance flat sheet gas separation membranes exhibit high permeances as well as high selectivities, e.g., for CO2 separation. Novel membrane modules are desirable to transfer the intrinsic membrane performance to the process. The introduced module implements countercurrent flow, which allows for the best utilization of the required driving force, provided concentration polarization and pressure drops can be kept at bay. As such, it is different from established flat sheet modules for gas separation. The design features allow for straightforward scaling and easy adjustment to other operating conditions. During module development equation‐oriented modeling, computer‐aided engineering design and application of computational fluid dynamics for flow optimization were integrated. The prototype was investigated in a pilot plant. The experimental results reflected the simulation predictions and proved the validity of the module concept. %0 journal article %@ 1022-1352 %A Abetz, V.,Kremer, K.,Mueller, M.,Reiter, G. %D 2019 %J Macromolecular Chemistry and Physics %N 2 %P 1800334 %R doi:10.1002/macp.201800334 %T Functional Macromolecular Systems: Kinetic Pathways to Obtain Tailored Structures %U https://doi.org/10.1002/macp.201800334 2 %X This article aims to stimulate research on non‐equilibrium macromolecular systems, as nowadays a large toolbox to synthesize tailored macromolecules is available. A large variety of characterization methods covering a broad spectrum of length and timescales allows researchers to follow and also manipulate macromolecular systems on their paths toward equilibrium. These possibilities are paralleled by the development of new concepts of the statistical physics of non‐equilibrium phenomena in macromolecular systems as well as new models and algorithms for computer simulation. %0 journal article %@ 1022-1336 %A Zhang, Z.,Rahman, M.,Abetz, C.,Bajer, B.,Wang, J.,Abetz, V. %D 2019 %J Macromolecular Rapid Communications %N 3 %P 1800729 %R doi:10.1002/marc.201800729 %T Quaternization of a Polystyrene‐block‐poly(4‐vinylpyridine) Isoporous Membrane: An Approach to Tune the Pore Size and the Charge Density %U https://doi.org/10.1002/marc.201800729 3 %X Isoporous integral asymmetric membranes derived from the self‐assembly of block copolymers combined with the non‐solvent‐induced phase separation (SNIPS) have gained great attention. To extend their utility, good control over pore size and surface functionality in a facile manner is highly desirable. Here, an approach is proposed to achieve this by quaternization of the poly(4‐vinylpyridine) moiety of a polystyrene‐block‐poly(4‐vinylpyridine) SNIPS membrane using alkyl iodides via a scalable gas‐solid heterogeneous reaction. By changing the size of the alkyl groups of the quaternization agent and the degree of quaternization, the effective pore size of the membrane is tailored in a wide range from the ultrafiltration to the nanofiltration regime. A quaternization of approximately half of the 4VP repeating units of the membranes with methyl iodide, ethyl iodide, or 1‐propyl iodide leads to a retention of methylene blue from a 10 mg L−1 aqueous solution of 96%, 87%, and 83%, respectively. %0 journal article %@ 0009-286X %A Georgopanos, P.,Weigelt, F.,Shishatskiy, S.,Filiz, V.,Brinkmann, T.,Abetz, V. %D 2019 %J Chemie - Ingenieur - Technik %N 4 %P 534-537 %R doi:10.1002/cite.201800071 %T Defektfreie Mixed‐Matrix‐Membranen aus Matrimid® und Aktivkohle für die Gastrennung : Defect‐Free Mixed‐Matrix Membranes from Matrimid® and Activated Carbon for Applications in Gas Separation %U https://doi.org/10.1002/cite.201800071 4 %X In dieser Arbeit wurden neue Mixed‐Matrix‐Membranen (MMM) aus Matrimid® und Aktivkohle (AK) für die Gasseparation untersucht. Das Ziel dieser Arbeit ist die Herstellung von Membranen mit im Vergleich zu reinen Matrimid®‐Membranen verbesserten Gaspermeationseigenschaften. Die Membranen wurden thermisch und morphologisch charakterisiert, außerdem wurden die Gastransporteigenschaften bestimmt. Bei steigendem AK‐Gehalt war die Selektivität für verschiedene Gaspaare konstant, die Permeabilitäten stiegen jedoch stark an. %0 journal article %@ 2077-0375 %A Lillepaerg, J.,Breitenkamp, S.,Shishatskiy, S.,Pohlmann, J.,Wind, J.,Scholles, C.,Brinkmann, T. %D 2019 %J Membranes %N 2 %P 22 %R doi:10.3390/membranes9020022 %T Characteristics of Gas Permeation Behaviour in Multilayer Thin Film Composite Membranes for CO2 Separation %U https://doi.org/10.3390/membranes9020022 2 %X Porous, porous/gutter layer and porous/gutter layer/selective layer types of membranes were investigated for their gas transport properties in order to derive an improved description of the transport performance of thin film composite membranes (TFCM). A model describing the individual contributions of the different layers’ mass transfer resistances was developed. The proposed method allows for the prediction of permeation behaviour with standard deviations (SD) up to 10%. The porous support structures were described using the Dusty Gas Model (based on the Maxwell–Stefan multicomponent mass transfer approach) whilst the permeation in the dense gutter and separation layers was described by applicable models such as the Free-Volume model, using parameters derived from single gas time lag measurements. The model also accounts for the thermal expansion of the dense layers at pressure differences below 100 kPa. Using the model, the thickness of a silicone-based gutter layer was calculated from permeation measurements. The resulting value differed by a maximum of 30 nm to the thickness determined by scanning electron microscopy. %0 journal article %@ 2296-4185 %A Opdensteinen, P.,Clodt, J.I.,Mueschen, C.R.,Filiz, V.,Buyel, J.F. %D 2019 %J Frontiers in Bioengineering and Biotechnology %N %P 206 %R doi:10.3389/fbioe.2018.00206 %T A Combined Ultrafiltration/Diafiltration Step Facilitates the Purification of Cyanovirin-N From Transgenic Tobacco Extracts %U https://doi.org/10.3389/fbioe.2018.00206 %X The production of biopharmaceutical proteins in plants offers many advantages over traditional expression platforms, including improved safety, greater scalability and lower upstream production costs. However, most products are retained within plant cells or the apoplastic space instead of being secreted into a liquid medium, so downstream processing necessarily involves tissue and cell disruption followed by the removal of abundant particles and host cell proteins (HCPs). We investigated whether ultrafiltration/diafiltration (UF/DF) can simplify the purification of the model recombinant protein cyanovirin-N (CVN), an ~11 kDa HIV-neutralizing lectin, from tobacco extracts prior to chromatography. We compared different membrane types and process conditions, and found that at pH 8.0 and 50 mS cm−1 an UF step using a 100 kDa regenerated cellulose membrane removed more than 80% of the ~0.75 mg mL−1 total soluble protein present in the clarified plant extract. We recovered ~70% of the CVN and the product purity increased ~3-fold in the permeate. The underlying effects of tobacco HCP retention during the UF/DF step were investigated by measuring the zeta potential and particle size distribution in the 2–10,000 nm range. Combined with a subsequent 10 kDa DF step, this approach simultaneously reduced the process volume, conditioned the process intermediate, and facilitated early, chromatography-free purification. Due to the generic, size-based nature of the method, it is likely to be compatible with most products smaller than ~50 kDa. %0 journal article %@ 2040-3364 %A Sankhala, K.,Wieland, D.C.F.,Koll, J.,Radjabian, M.,Abetz, C.,Abetz, V. %D 2019 %J Nanoscale %N 16 %P 7634-7647 %R doi:10.1039/C8NR06892E %T Self-assembly of block copolymers during hollow fiber spinning: an in situ small-angle X-ray scattering study %U https://doi.org/10.1039/C8NR06892E 16 %X We investigated the self-assembly of block copolymers during hollow fiber membrane (HFM) fabrication by conducting in situ small angle X-ray scattering (SAXS) and ex situ scanning electron microscopy (SEM) studies. SAXS enables us to follow the structural rearrangements after extrusion at different distances from the spinning nozzle. The kinetics of the spinning process is examined as a function of the composition of block copolymer solutions and the spinning parameters. We studied the influence of the extrusion rate on the block copolymer microdomains and their self-assembly in weakly segregated and ordered solutions. The addition of magnesium acetate (MgAc2) leads to the ordering of micelles in the block copolymer solution already at lower polymer concentrations and shows an increased number of micelles with larger domain spacing as compared to the pristine solution. The SAXS data show the effect of shear within the spinneret on the self-assembly of block copolymers and the kinetics of phase separation after extrusion. It is observed that the ordering of micelles in solutions is decreased as indicated by the loss of crystallinity while high extrusion rates orient the structures perpendicular to the fiber direction. The structural features obtained from in situ SAXS experiments are correlated to the structure in the block copolymer solutions in the absence of shear and the morphologies in flat sheet and HF membranes obtained by ex situ SEM. This allows a systematic and comparative study of the effects varying the microdomain ordering within different block copolymer solutions and the formed membrane structures. %0 journal article %@ 0376-7388 %A Böcking, A.,Koleva, V.,Wind, J.,Thiermeyer, Y.,Blumenstein, S.,Goebel, R.,Skiborowski, M.,Wessling, M. %D 2019 %J Journal of Membrane Science %N %P 217-228 %R doi:10.1016/j.memsci.2018.12.077 %T Can the variance in membrane performance influence the design of organic solvent nanofiltration processes? %U https://doi.org/10.1016/j.memsci.2018.12.077 %X The development of organic solvent nanofiltration (OSN) membranes has been a continuous effort during the past decade. Several groups generated and published experimental results and simulations with either tailor-made membranes or industrial products. The published data space is diverse, with a single publication often focusing on a certain membrane only, a group of specific solutes only, on the effect of solvent only. A comprehensive comparison of all of these is still lacking. An analysis on the reliability of quantified transport parameters is missing, in particular when different analysis methods and different membrane systems are used. The technology is in its incubation phase with a need for reliable data and measurement standards to ground the process design on reliable membrane transport properties. This study uses an unprecedented extensive standard experimental procedure to measure separation characteristics of polymer membranes for the separation of organic solutes from organic solvents.,For a variety of different solvents, solutes and membranes, flux and retention measurements are rigorously characterized by round robin tests at different labs using different analytical systems. This extensive collaborative study evaluates for the first time which fluctuations in results occur under comparable conditions of lab-scale experiments at different locations and which influence these have on the design of OSN processes.,Utilizing the variance in the membrane transport data, a process design study and optimization is presented. For the first time ever, we report how variance in membrane transport properties can influence the process design ranging from a simple single stage system for values for the upper transport limits, to a two stage system with a permeate recirculation for mean values, to a complex three stage system for the lower limits. %0 journal article %@ 0032-3861 %A Wen, T.,Wang, H.-F.,Georgopanos, P.,Avgeropoulos, A.,Ho, R.-M. %D 2019 %J Polymer %N %P 209-214 %R doi:10.1016/j.polymer.2019.01.047 %T Three-dimensional visualization of phase transition in polystyrene-block-polydimethylsiloxane thin film %U https://doi.org/10.1016/j.polymer.2019.01.047 %X Herein, we aim to examine the order-order transition (OOT) of self-assembled block copolymer (BCP) under spatial confinement using double gyroid (DG) structured polystyrene-block-polydimethylsiloxane (PS-PDMS) thin film as an exemplary system for three-dimensional (3D) visualization of phase transitions. An interesting OOT from DG to hexagonally perforated lamellae (HPL) can be found after thermal annealing, and the morphological evolution and corresponding mechanism for the OOT was systematically investigated by 3D transmission electron microscopy (3D TEM). Our results revealed that the phase transition of DG nanostructure in thin film was different from that in bulk, which is attributed into the surficial/interfacial effects and the effect of confinement on BCP self-assembly. This work provides a feasible method to prepare DG-nanostructured thin film and presents a model system for the examination of morphological evolution from metastable to phase with higher thermodynamic stability in the thin-film state through the OOT. %0 journal article %@ 2052-2525 %A Chiu, P.-T.,Chien, Y.-C.,Georgopanos, P.,Sun, Y.-S.,Avgeropoulos, A.,Ho, R.-M. %D 2019 %J IUCrJ - International Union of Crystallography %N 2 %P 259-266 %R doi:10.1107/S2052252518018389 %T Examination of well ordered nanonetwork materials by real- and reciprocal-space imaging %U https://doi.org/10.1107/S2052252518018389 2 %X The development of well ordered nanonetwork materials (in particular gyroid-structured materials) has been investigated using a block-copolymer template for templated electroless plating as an example system for the examination of network formation using X-ray scattering. By taking advantage of the nucleation and growth mechanism of templated electroless plating, gyroid-structured Au was successfully fabricated through the development of Au nanoparticles, then tripods and branched tripods, and finally an ordered network. Each stage in the development of the network phase could then be examined by combining real-space transmission electron microscopy observations with reciprocal-space small-angle X-ray scattering results. The fingerprint scattering profile of the building block for the network (i.e. the tripod of the gyroid) could be well fitted with the form factor of an effective sphere, and the diffraction results from the ordered network could thus be reasonably addressed. As a result, the examination of well ordered network materials can be simplified as the scattering from the form factor of a sphere convoluted with the nodes of its structure factor, providing a facile method of identifying the network phases from X-ray scattering data. %0 journal article %@ 2077-0375 %A Weigelt, F.,Escorihuela, S.,Descalzo, A.,Tena, A.,Escolastico, S.,Shishatskiy, S.,Serra, J.M.,Brinkmann, T. %D 2019 %J Membranes %N 4 %P 51 %R doi:10.3390/membranes9040051 %T Novel Polymeric Thin-Film Composite Membranes for High-Temperature Gas Separations %U https://doi.org/10.3390/membranes9040051 4 %X Novel selective polymeric thin-film composite membranes (TFCMs) for applications at elevated temperatures were developed. Thin selective layers of the polyimides Matrimid 5218® and 6FDA-6FpDA were cast on a developed polybenzimidazole (PBI) porous support prepared by a phase inversion process. The TFCM properties were investigated with different gases in a wide temperature range, including temperatures up to 270 °C. The membranes showed very high thermal stability and performed well at the elevated temperatures. The development of highly thermally resistant polymeric membranes such as these TFCMs opens opportunities for application in high-temperature integrated processes, such as catalytic membrane reactors for the water-gas shift reaction in order to maximize H2 yield. %0 journal article %@ 1463-9262 %A Bailer, J.,Feth, S.,Bretschneider, F.,Rosenfeldt, S.,Drechsler, M.,Abetz, V.,Schmalz, H.,Greiner, A. %D 2019 %J Green Chemistry %N 9 %P 2266-2272 %R doi:10.1039/C9GC00250B %T Synthesis and self-assembly of biobased poly(limonene carbonate)-block-poly(cyclohexene carbonate) diblock copolymers prepared by sequential ring-opening copolymerization %U https://doi.org/10.1039/C9GC00250B 9 %X Polycarbonate diblock copolymers with a biobased poly(limonene carbonate) (PLimC) and a poly(cyclohexene carbonate) (PCHC) block were prepared via β-diiminate zinc catalysed living ring-opening copolymerization (ROCOP) of CO2 and trans-limonene oxide and cyclohexene oxide, respectively. trans-Limonene oxide can be readily obtained from limonene, a renewable non-food source, that can be found in the peel of many citrus fruits and is the main component of orange oil. The block formation was realised by sequential addition of the epoxide monomers. The composition of the resulting amorphous poly(limonene carbonate)-block-poly(cyclohexene carbonate) (PLimC-b-PCHC) diblock copolymers was analysed by 1H NMR spectroscopy. The self-assembly of the diblock copolymers into well-defined bulk morphologies was studied by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Depending on the composition and molecular weight the formation of cylindrical, lamellar, and hexagonally perforated lamellar morphologies was observed. %0 journal article %@ 2077-0375 %A Klingberg, P.,Wilkner, K.,Schlueter, M.,Gruenauer, J.,Shishatskiy, S. %D 2019 %J Membranes %N 3 %P 35 %R doi:10.3390/membranes9030035 %T Separation of Carbon Dioxide from Real Power Plant Flue Gases by Gas Permeation Using a Supported Ionic Liquid Membrane: An Investigation of Membrane Stability %U https://doi.org/10.3390/membranes9030035 3 %X The separation of carbon dioxide from coal-fired power plant flue gases using a CO2/N2-selective supported ionic liquid membrane (SILM) was investigated and the performance and stability of the membrane during operation are reported. The membrane is composed of a polyacrylonitrile (PAN) ultrafiltration membrane as a support and a selective layer of an ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM Tf2N). The feasibility of large-scale SILM production was demonstrated by the formation of a square-meter-scale membrane and preparation of a membrane module. A flat-sheet envelope-type SILM module containing 0.67 m2 of the membrane was assembled. Prior to real flue gas operation, the separation behaviour of the membrane was investigated with single gases. The stability of the SILM during the test stand and pilot plant operation using real power plant flue gases is reported. The volume fraction of carbon dioxide in the flue gas was raised from approx. 14 vol. % (feed) to 40 vol. % (permeate). However, issues concerning the membrane stability were found when SO3 aerosols in large quantities were present in the flue gas. %0 journal article %@ 1022-1352 %A Haenelt, T.G.,Meyer, A.,Abetz, C.,Abetz, V. %D 2019 %J Macromolecular Chemistry and Physics %N 20 %P 1900297 %R doi:10.1002/macp.201900297 %T Planet‐Like Nanostructures Formed by an ABC Triblock Terpolymer %U https://doi.org/10.1002/macp.201900297 20 %X A novel planet-like nanostructure formed by an asymmetric polystyrene-block-polyisoprene-block-poly(methyl methacrylate) (SIM) triblock terpolymer is presented, where polystyrene (PS) forms spherical microdomains, covered by polyisoprene (PI) rings/helices/polar caps and poly(methyl methacrylate) (PMMA) forms the matrix. The new nanostructure is the result of a thermally induced morphological transition of a kinetically trapped helical nanostructure by thermal annealing above its glass transition temperature. This new nanostructure is observed when the triblock terpolymer solution is cast from chloroform (CHCl3). When cast from tetrahydrofuran (THF) or toluene, mainly cylindrical and to a lesser extent spherical microdomains are observed. This is caused by a selectivity of the CHCl3 for the PS and PMMA microdomains. The SIM triblock terpolymer is synthesized by anionic polymerization, and the morphology is characterized by transmission electron microscopy, atomic force microscopy, and small angle X-ray scattering. %0 journal article %@ 1022-1352 %A Abetz, V.,Loos, K. %D 2019 %J Macromolecular Chemistry and Physics %N 20 %P 1900370 %R doi:10.1002/macp.201900370 %T In Honor of Reimund Stadler %U https://doi.org/10.1002/macp.201900370 20 %X no abstract %0 journal article %@ 1996-1944 %A Polevaya, V.,Geiger, V.,Bondarenko, G.,Shishatskiy, S.,Khotimskiy, V. %D 2019 %J Materials %N 17 %P 2763 %R doi:10.3390/ma12172763 %T Chemical Modification of Poly(1-Trimethylsylil-1-Propyne) for the Creation of Highly Efficient CO2-Selective Membrane Materials %U https://doi.org/10.3390/ma12172763 17 %X The work is devoted to the chemical modification of a polymer that is promising for the creation of gas separation membranes, aimed at increasing the selectivity with respect to CO2. The introduction of ionic liquids into the structure of poly(1-trimethylsilyl-1-propyne) is realized by a two-step process: bromination of the initial polymer with N-bromosuccinimide and subsequent addition of tertiary amine (N-butylimidazole) to it. Depending on the process conditions, the method allows polymers with different contents of the ionic liquid to be obtained. The obtained polymers show good film-forming properties and thermal stability. Depending on the content of the ionic liquid in the polymer matrix, the resistance to aliphatic alicyclic to the majority of halogenated, as well as aromatic hydrocarbons, increases. With an increase of the ionic liquid content in the polymer, the ideal selectivities of CO2/N2 and CO2/CH4 gas pairs increases while maintaining a high level of permeability. %0 journal article %@ 2073-4360 %A Neumann, S.,Bengtson, G.,Meis, D.,Filiz, V. %D 2019 %J Polymers %N 8 %P 1241 %R doi:10.3390/polym11081241 %T Thermal Cross Linking of Novel Azide Modified Polymers of Intrinsic Microporosity—Effect of Distribution and the Gas Separation Performance %U https://doi.org/10.3390/polym11081241 8 %X The synthesis of polymers of intrinsic microporosity (PIM) modified with azide groups, the cross linkage by nitrene reaction and their performance as gas separation membranes are reported. The azide modification of the spirobisindane units in the polymer backbone was done by post functionalization of methylated spirobisindane containing polymers. These polymers differ in distribution and concentration of the azide group containing spirobisindane units by applying perfectly alternating and randomly distributed copolymers along the polymer chains. To investigate the influence of concentration of the azide groups, additionally the homopolymer of methylated spirobisindane was synthesized and subjected to identical treatments and characterizations as both copolymers. Cross linkage by nitrene reaction was examined by different temperature treatments at 150, 200, 250 and 300 °C. Characterization of the new polymers was performed by NMR, SEC and FT-IR. Furthermore, the crosslinking process was investigated by means of solid state NMR, TGA-FTIR, DSC and isoconversional kinetic analysis performed with TGA. Gas permeability of CO2, N2, CH4, H2 and O2 was determined by time lag experiments and ideal selectivities for several gas pairs were calculated. The two azide groups per repeating unit degrade during thermal treatments by release of nitrogen and form mechanically stable PIM networks, leading to an increase in gas permeability while selectivity remained nearly constant. Measured diffusivity and solubility coefficients revealed differences in the formation of free volume elements depending on distribution and concentration of the azide groups. Aging studies over about five months were performed and physical aging rates (βP) were evaluated with regard to the concentration and distribution of curable azide functionalities. Subsequently, the enhanced sieving effect during aging resulted in membrane materials that surpassed the Robeson upper bound in selected gas pairs. %0 journal article %@ 2077-0375 %A Schmitt, S.,Shishatskiy, S.,Krolla, P.,An, Q.,Begum, S.,Welle, A.,Hashem, T.,Grosjean, S.,Abetz, V.,Bräse, S.,Wöll, C.,Tsotsalas, M. %D 2019 %J Membranes %N 19 %P 124 %R doi:10.3390/membranes9100124 %T Synthesis, Transfer, and Gas Separation Characteristics of MOF-Templated Polymer Membranes %U https://doi.org/10.3390/membranes9100124 19 %X This paper discusses the potential of polymer networks, templated by crystalline metal–organic framework (MOF), as novel selective layer material in thin film composite membranes. The ability to create mechanically stable membranes with an ultra-thin selective layer of advanced polymer materials is highly desirable in membrane technology. Here, we describe a novel polymeric membrane, which is synthesized via the conversion of a surface anchored metal–organic framework (SURMOF) into a surface anchored gel (SURGEL). The SURGEL membranes combine the high variability in the building blocks and the possibility to control the network topology and membrane thickness of the SURMOF synthesis with high mechanical and chemical stability of polymers. Next to the material design, the transfer of membranes to suitable supports is also usually a challenging task, due to the fragile nature of the ultra-thin films. To overcome this issue, we utilized a porous support on top of the membrane, which is mechanically stable enough to allow for the easy membrane transfer from the synthesis substrate to the final membrane support. To demonstrate the potential for gas separation of the synthesized SURGEL membranes, as well as the suitability of the transfer method, we determined the permeance for eight gases with different kinetic diameters. %0 journal article %@ 1996-1944 %A Nieswandt, K.,Georgopanos, P.,Abetz, C.,Filiz, V.,Abetz, V. %D 2019 %J Materials %N 19 %P 3145 %R doi:10.3390/ma12193145 %T Synthesis of Poly(3-vinylpyridine)-Block-Polystyrene Diblock Copolymers via Surfactant-Free RAFT Emulsion Polymerization %U https://doi.org/10.3390/ma12193145 19 %X In this work, we present a novel synthetic route to diblock copolymers based on styrene and 3-vinylpyridine monomers. Surfactant-free water-based reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of styrene in the presence of the macroRAFT agent poly(3-vinylpyridine) (P3VP) is used to synthesize diblock copolymers with molecular weights of around 60 kDa. The proposed mechanism for the poly(3-vinylpyridine)-block-poly(styrene) (P3VP-b-PS) synthesis is the polymerization-induced self-assembly (PISA) which involves the in situ formation of well-defined micellar nanoscale objects consisting of a PS core and a stabilizing P3VP macroRAFT agent corona. The presented approach shows a well-controlled RAFT polymerization, allowing for the synthesis of diblock copolymers with high monomer conversion. The obtained diblock copolymers display microphase-separated structures according to their composition. %0 journal article %@ 2079-4991 %A Aliyev, E.,Filiz, V.,Khan, M.M.,Lee, Y.J.,Abetz, C.,Abetz, V. %D 2019 %J Nanomaterials %N 8 %P 1180 %R doi:10.3390/nano9081180 %T Structural Characterization of Graphene Oxide: Surface Functional Groups and Fractionated Oxidative Debris %U https://doi.org/10.3390/nano9081180 8 %X The purpose of this work is the structural analysis of graphene oxide (GO) and by means of a new structural model to answer the questions arising from the Lerf–Klinowski and the Lee structural models. Surface functional groups of GO layers and the oxidative debris (OD) stacked on them were investigated after OD was extracted. Analysis was performed successfully using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (SSNMR), standardized Boehm potentiometric titration analysis, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The analysis showed that graphene oxide layers, as well as oxidative debris contain different functional groups such as phenolic –OH, ketone, lactone, carboxyl, quinone and epoxy. Based on these results, a new structural model for GO layers is proposed, which covers all spectroscopic data and explains the presence of the other oxygen functionalities besides carboxyl, phenolic –OH and epoxy groups. %0 journal article %@ 0009-286X %A Panglisch, S.,Shalmani, A.K.,Weber, M.,Gronwald, O.,Berg, P.,Heijnen, M.,Krug, M.,Koti, M.,Nahrstedt, A.,Abetz, V.,Handge, U.A.,Gruenig, L.,Ulbricht, M.,Stratmann, I. %D 2019 %J Chemie - Ingenieur - Technik %N 8 %P 1162-1167 %R doi:10.1002/cite.201900038 %T Material‐Auswahlbox zur Herstellung fortgeschrittener Polymermembranen für die Wasseraufbereitung : Material Selection Box for the Production of Advanced Polymer Membranes for Water Treatment %U https://doi.org/10.1002/cite.201900038 8 %X Im Rahmen des Forschungsprojektes MABMEM werden neue, leistungsfähige Membranen für eine nachhaltige Wasserwirtschaft entwickelt. Die Leistungsfähigkeit der Membranen wird in vergleichenden und standardisierten Foulingtests sowie in Bezug auf die Abtrennung von Spurenverunreinigungen im Labormaßstab evaluiert. Sieben Kandidaten werden derzeit in Demonstratorversuchen mit Realwassermatrix in einem Wasserwerk zur direkten Aufbereitung eines Talsperrenwassers ohne vorherige Flockung über einen Zeitraum von 6 Monaten getestet. Im Anschluss werden die neuen Membranmaterialien mit dem Ablauf einer Kläranlage betrieben.,Within the framework of the MABMEM research project, new high‐performance membranes are being developed for sustainable water management. The performance of the membranes will be evaluated in comparative and standardized fouling tests as well as in terms of the removal of trace impurities on a laboratory scale. Seven candidates are currently being tested in demonstrator trials with real‐water matrix in a waterworks for the direct treatment of dam water without prior coagulation over a period of 6 months. Subsequently, the new membrane materials will be operated with the effluent of a wastewater treatment plant. %0 journal article %@ 2196-7350 %A Dreyer, O.,Wu, M.-L.,Radjabian, M.,Abetz, C.,Abetz, V. %D 2019 %J Advanced Materials Interfaces %N 17 %P 1900646 %R doi:10.1002/admi.201900646 %T Structure of Nonsolvent‐Quenched Block Copolymer Solutions after Exposure to Electric Fields during Solvent Evaporation %U https://doi.org/10.1002/admi.201900646 17 %X In this work, an electric field is incorporated during the solvent evaporation step of the block copolymer self‐assembly and nonsolvent induced phase separation (SNIPS) process. This study investigates the structure of nonsolvent‐quenched polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) and polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) diblock copolymer solutions after exposure to electric fields during solvent evaporation. The results indicate an emphasizing effect of the electric field, enhancing self‐assembly and compensating mediocre experimental parameters to a certain degree. However, the impact is found to be different for the two diblock copolymer membranes depending on the selection of experimental parameters as well as the segregation strength of the systems. In addition, an increasing length of the vertically aligned cylindrical pores by the electric field is observed for both membranes, scaling with the applied voltage. This effect is primarily attributed to the suppression of defects and ill‐alignment of polymer domains in the course of structure formation during SNIPS by the electric field. Scanning electron microscopy is used to image the surface and cross‐sectional morphology of the integral asymmetric membranes. %0 journal article %@ 0035-4511 %A Handge, U.A.,Gronwald, O.,Weber, M.,Hankiewicz, B.,Abetz, V. %D 2019 %J Rheologica Acta %N 9 %P 591-602 %R doi:10.1007/s00397-019-01160-0 %T Phase behavior and dynamics of Pluronic®-based additives in semidilute solutions of poly(ethersulfone) and poly(N-vinyl pyrrolidone): rheological and dynamic light scattering experiments %U https://doi.org/10.1007/s00397-019-01160-0 9 %X The phase behavior and dynamical properties of a pristine Pluronic® F127 and a Pluronic®-based multiblock copolymer, respectively, in semidilute solutions of poly(ethersulfone) (PESU) and poly(N-vinyl pyrrolidone) (PVP) in N-methyl-2-pyrrolidone (NMP) are investigated using shear rheological and dynamic light scattering (DLS) experiments. Pluronic® F127 is used for synthesis of the PESU-based multiblock copolymer. If the concentration of this additive exceeds a critical value, the solutions are characterized by a pronounced elasticity because of the phase behavior of the solutions, i.e., the polymer solution with three polymeric components depicts a miscibility gap which is associated with an interfacial tension in the two-phase regime. The addition of pristine Pluronic® F127 or the Pluronic®-based multiblock copolymer leads to an additional relaxation process. The zero shear rate viscosity data are qualitatively reproduced by the Palierne model. Phase separation above the critical concentration is supported by a relatively low diffusion coefficient as determined by DLS experiments. %0 journal article %@ 0033-4545 %A Fischer, B.,Abetz, V. %D 2018 %J Pure and Applied Chemistry %N 6 %P 955-968 %R doi:10.1515/pac-2017-1101 %T Determination of thermodynamic and structural quantities of polymers by scattering techniques %U https://doi.org/10.1515/pac-2017-1101 6 %X Scattering techniques (i.e. light scattering, X-ray scattering, or neutron scattering) are very powerful tools to gain insights into structural and thermodynamic properties of matter which often cannot be obtained by other methods. While classical thermodynamics is independent of length scale or applies for indefinitely long length scale, scattering can disclose thermodynamic properties like the free energy or free enthalpy as functions of length scale. Scattering is caused by density or composition fluctuations, which are functions of the length scale in one- or multicomponent systems. Therefore scattering techniques can give informations about the size, shape and molecular weight of scattering objects, their thermodynamic interactions with a surrounding matrix and their dynamics if correlations of the fluctuations as function of time are investigated (i.e. dynamic light scattering). As scattering techniques are less intuitive in comparison to complementary techniques, i.e. microscopic techniques, the aim of this article is to highlight some relevant relationships with a focus on polymer systems. This may encourage polymer scientists to consider the use of scattering techniques to learn more about the thermodynamics of their systems and/or to gain informations about their structural properties. %0 journal article %@ 2161-1653 %A Sankhala, K.,Koll, J.,Abetz, V. %D 2018 %J ACS Macro Letters %N 7 %P 840-845 %R doi:10.1021/acsmacrolett.8b00402 %T Setting the Stage for Fabrication of Self-Assembled Structures in Compact Geometries: Inside-Out Isoporous Hollow Fiber Membranes %U https://doi.org/10.1021/acsmacrolett.8b00402 7 %X Fabrication of evaporation-induced self-assembled structures on easily accessible surfaces is an established strategy, while achieving such microphase-separated structures in compact geometries has been a long-standing goal. The requirement of comparatively less concentrated block copolymer (BCP) solution to pass through the compact geometries significantly reduces the stimulations required for self-assembly. The high polymer relaxation rates and decreased thermodynamic driving forces, as well as high capillary suction of dilute solutions in the porous substrates, complicates the BCP self-assembly and fabrication of the uniform coated layer, respectively. In this study, highly permeable robust poly(ether sulfone) hollow fiber membranes (PES HFM) with an inner diameter of approximately 1 mm are selected as compact geometries, and the isoporous structures are developed on top of ≤10 μm thin coated layer. This fabrication process introduces a technologically favored inside-out configuration for isoporous composite HFM with large bore diameters. %0 journal article %@ 1381-5148 %A Diez, B.,Cuadrado, P.,Marcos-Fernandez, M.,de la Campa, J.G.,Tena, A.,Pradanos, P.,Palacio, L.,Lee, Y.M.,Alvarez, C.,Lotano, A.E.,Hernandez, A. %D 2018 %J Reactive and Functional Polymers %N %P 38-47 %R doi:10.1016/j.reactfunctpolym.2018.03.013 %T Thermally rearranged polybenzoxazoles made from poly(ortho-hydroxyamide)s. Characterization and evaluation as gas separation membranes %U https://doi.org/10.1016/j.reactfunctpolym.2018.03.013 %X Two series of aromatic poly(ortho-hydroxyamide)s (poly(o-hydroxyamide)s, HPAs) were prepared by reaction of two diamines, 2,2-bis(3-amino-4-hydroxyphenyl) propane (APA) and 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF), with four aromatic diacid chlorides; terephthaloyl dichloride (TPC), isophthaloyl dichloride (IPC), 2,2-bis[4-chlorocarbonylphenyl)hexafluoropropane (6FC) and 4,4′-sulfonyldibenzoyl dichloride (DBSC). Amorphous HPAs with high molecular weights (inherent viscosities higher than 0.5 dL/g) and relatively high glass transition temperatures (220–280 °C) were obtained. Dense membranes of HPAs were able to undergo a thermal rearrangement (TR) process to polybenzoxazoles (β-TR-PBOs) heating at moderate temperatures (between 250 and 375 °C), and their complete conversion was reached at a temperature below 375 °C, depending on the o-hydroxy diamine moiety, APA and APAF. The β-TR-PBOs films derived from APAF showed a higher thermal stability and higher Tg than those from APA. Gas separation properties of TR-PBOs membranes were superior to those of their poly(o-hydroxyamide) precursors, particularly for the following gas pairs: O2/N2, CO2/CH4, He/CH4 and He/CO2. %0 journal article %@ 0014-3057 %A Escorial, L.,de la Viuda, M.,Rodriguez, S.,Tena, A.,Marcos, A.,Palacio, L.,Pradanos, P.,Lozano, A.E.,Hernandez, A. %D 2018 %J European Polymer Journal %N %P 390-399 %R doi:10.1016/j.eurpolymj.2018.04.031 %T Partially pyrolized gas-separation membranes made from blends of copolyetherimides and polyimides %U https://doi.org/10.1016/j.eurpolymj.2018.04.031 %X Herein, a new approach to achieve gas separation materials with improved resistance to plasticization (obtained by partial pyrolysis of new polyimide blends) is presented. Blends of an aromatic polyimide (formally, 6FDA-6FpDA) and aliphatic-aromatic copolyetherimides based on the same polyimide in combination with other aliphatic polyimides, having polyethylene oxide moieties, were obtained. After their synthesis and characterization, a selective elimination of the polyether by thermal treatment was carried and the obtained partially-pyrolyzed materials were tested as gas separation membranes.,For neat blends, permeability was shown to decrease when PEO content increases. This effect is due to polyethylene oxide (PEO) chains encroaching on free volume because phase segregation was minimized. When these blends were subjected to thermal treatment at relatively low temperatures in air or in N2, it was clearly observed that all the polyether moieties were selectively eliminated from the structure, which gave rise to an increase of permeability. Higher permeabilities were obtained after a thermal treatment at 390 °C in N2. Degradation of PEO chains after a 290 °C treatment in air produced materials with permeability values lower than those observed under N2. In both cases, even though PEO was selectively and wholly eliminated, permeability was not totally recovered to give the values observed for neat 6FDA-6FpDA due probably to a combination of shrinkage and crosslinking of the membrane produced during the thermal process. Crosslinking provides the materials with an increased resistance to plasticization. In particular, the best improvement against plasticization proceeded from the thermal treatments of blends at 290 °C in air. %0 journal article %@ 2077-0375 %A Schuldt, K.,Pohlmann, J.,Shishatskiy, S.,Brinkmann, T. %D 2018 %J Membranes %N 2 %P 27 %R doi:10.3390/membranes8020027 %T Applicability of PolyActive™ Thin Film Composite Membranes for CO2 Separation from C2H4 Containing Multi-Component Gas Mixtures at Pressures up to 30 Bar %U https://doi.org/10.3390/membranes8020027 2 %X The PolyActive™ thin film composite membrane (TFCM) has already been successfully applied for CO2 separation tasks at feed pressures up to 10 bar. To investigate the applicability at higher pressures, measurements were undertaken with C2H4 containing gas mixtures with a composition comparable to the product stream of the oxidative coupling of methane process, as well as single gases up to a feed pressure of 30 bar. Furthermore, the permeances of the conducted gas mixture experiments were simulated. The results show a strong swelling influence of CO2 on the used membrane depending on the CO2 fugacity. This swelling effect leads to a pronounced decrease in selectivity. The observed membrane behavior at high pressures could not be predicted by the Free Volume Model (FVM). Two different simulations were conducted: one based on parameters calculated from single gas data measured at pressures up to 2 bar; and a second based on parameters calculated from single gas data measured at pressures from 2 to 30 bar. The two simulations differ in their prediction accuracy. However, they confirm that it is possible to predict the measured permeances in the pressure range up to an average CO2 fugacity of 6 bar. %0 journal article %@ 2574-0970 %A Hoehme, C.,Filiz, V.,Abetz, C.,Georgopanos, P.,Scharnagl, N.,Abetz, V. %D 2018 %J ACS Applied Nano Materials %N 7 %P 3124-3136 %R doi:10.1021/acsanm.8b00289 %T Postfunctionalization of Nanoporous Block Copolymer Membranes via Click Reaction on Polydopamine for Liquid Phase Separation %U https://doi.org/10.1021/acsanm.8b00289 7 %X In this work, an azido-modified dopamine derivative was synthesized and subsequently used to postfunctionalize the surface of nanoporous poly(styrene)-block-poly(4-vinylpyridine) diblock copolymer membranes. On the basis of this layer a continuative modification was realized by performing a “Click” reaction, namely, the Cu(I)-catalyzed 1,3-dipolar cycloaddition, with different alkynes. While the Click reaction was monitored by X-ray photoelectron spectroscopy, the morphology of the membranes in the different states of modification was examined with scanning electron microscopy and atomic force microscopy. The membrane properties were characterized by measurements of contact angle and clean water permeance, retention tests, and protein adsorption. Independent from the alkyne applied during the Click reaction, the clean water permeance is approximately 1200 L m–2 bar–1 h–1 and therefore slightly below the permeance of the pristine membrane. While the sharp molecular weight cutoff of the pristine membrane and all modified membranes is similar, antifouling properties as studied on the interaction of two model proteins (bovine serum albumin, hemoglobin) with the membranes turned out to be best for the membranes modified with 1-nonyne. %0 journal article %@ 2077-0375 %A Escorihuela, S.,Tena, A.,Shishatskiy, S.,Escolastico, S.,Brinkmann, T.,Serra, J.M.,Abetz, V. %D 2018 %J Membranes %N 1 %P 16 %R doi:10.3390/membranes8010016 %T Gas Separation Properties of Polyimide Thin Films on Ceramic Supports for High Temperature Applications %U https://doi.org/10.3390/membranes8010016 1 %X Novel selective ceramic-supported thin polyimide films produced in a single dip coating step are proposed for membrane applications at elevated temperatures. Layers of the polyimides P84®, Matrimid 5218®, and 6FDA-6FpDA were successfully deposited onto porous alumina supports. In order to tackle the poor compatibility between ceramic support and polymer, and to get defect-free thin films, the effect of the viscosity of the polymer solution was studied, giving the entanglement concentration (C*) for each polymer. The C* values were 3.09 wt. % for the 6FDA-6FpDA, 3.52 wt. % for Matrimid®, and 4.30 wt. % for P84®. A minimum polymer solution concentration necessary for defect-free film formation was found for each polymer, with the inverse order to the intrinsic viscosities (P84® ≥ Matrimid® >> 6FDA-6FpDA). The effect of the temperature on the permeance of prepared membranes was studied for H2, CH4, N2, O2, and CO2. As expected, activation energy of permeance for hydrogen was higher than for CO2, resulting in H2/CO2 selectivity increase with temperature. More densely packed polymers lead to materials that are more selective at elevated temperatures. %0 journal article %@ 0033-4545 %A Chan, C.H.,Abetz, V.,Mukbaniani, O. %D 2018 %J Pure and Applied Chemistry %N 6 %P 937-938 %R doi:10.1515/pac-2018-0403 %T 25th World Forum on Advanced Materials (POLYCHAR-25) %U https://doi.org/10.1515/pac-2018-0403 6 %X No abstract %0 journal article %@ 1744-683X %A Wittenberg, E.,Meyer, A.,Eggers, S.,Abetz, V. %D 2018 %J Soft Matter %N %P 2701-2711 %R doi:10.1039/c8sm00296g %T Hydrogen bonding and thermoplastic elastomers – A nice couple with temperature-adjustable mechanical properties %U https://doi.org/10.1039/c8sm00296g %X Styrene–butadiene copolymers are modified with varying fractions of benzoic acid moieties being able to perform hydrogen bonding. This is done by using a simple synthetic approach which utilizes click chemistry. Temperature-dependent dynamic mechanical properties are studied, and it turns out that even the apparently rather simple hydrogen bonding motif has a marked impact on the material properties due to the fact that it facilitates the formation of a supramolecular polymer network. Besides a glass transition, the investigated functionalized copolymers exhibit a second endothermic transition, known as a quasi-melting. This is related to the opening of the hydrogen bonding complexes. Additionally to dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), temperature-dependent infrared (IR) spectroscopy and small angle X-ray scattering (SAXS) are used to understand the structure–property relationships. %0 journal article %@ 1613-6810 %A Krishnan, M.R.,Lu, k.-Y.,Chiu, W.-Y.,Chen Chen, I.,Lin, J.-W.,Lo, T.-Y.,Georgopanos, P.,Avgeropoulos, A.,Lee, M.-C.,Ho, R.-M. %D 2018 %J Small %N 16 %P 1704005 %R doi:10.1002/smll.201704005 %T Directed Self-Assembly of Star-Block Copolymers by Topographic Nanopatterns through Nucleation and Growth Mechanism %U https://doi.org/10.1002/smll.201704005 16 %X Exploring the ordering mechanism and dynamics of self‐assembled block copolymer (BCP) thin films under confined conditions are highly essential in the application of BCP lithography. In this study, it is aimed to examine the self‐assembling mechanism and kinetics of silicon‐containing 3‐arm star‐block copolymer composed of polystyrene (PS) and poly(dimethylsiloxane) blocks as nanostructured thin films with perpendicular cylinders and controlled lateral ordering by directed self‐assembly using topographically patterned substrates. The ordering process of the star‐block copolymer within fabricated topographic patterns with PS‐functionalized sidewall can be carried out through the type of secondary (i.e., heterogeneous) nucleation for microphase separation initiated from the edge and/or corner of the topographic patterns, and directed to grow as well‐ordered hexagonally packed perpendicular cylinders. The growth rate for the confined microphase separation is highly dependent upon the dimension and also the geometric texture of the preformed pattern. Fast self‐assembly for ordering of BCP thin film can be achieved by lowering the confinement dimension and also increasing the concern number of the preformed pattern, providing a new strategy for the design of BCP lithography from the integration of top‐down and bottom‐up approaches. %0 journal article %@ 1022-1336 %A Wang, J.,Rahman, M.M.,Abetz, C.,Rangou, S.,Zhang, Z.,Abetz, V. %D 2018 %J Macromolecular Rapid Communications %N 18 %P 1800435 %R doi:10.1002/marc.201800435 %T Novel Post-Treatment Approaches to Tailor the Pore Size of PS-Beta-PHEMA Isoporous Membranes %U https://doi.org/10.1002/marc.201800435 18 %X Using the example of an integral‐asymmetric isoporous membrane prepared from polystyrene‐block‐poly(2‐hydroxyethyl methacrylate) (PS‐b‐PHEMA), physical and chemical ways of post‐treatment are introduced with the aim to tailor the pore size. These post‐treatments are i) thermal annealing and ii) urethane chemistry of ethyl isocyanate (EI) in the presence of perfluoro(methyl cyclohexane). Via these approaches, the pore size of PS‐b‐PHEMA membranes is successfully tailored in the range of 10–20 nm with narrow pore size distribution by controlling the duration of thermal annealing and chemical reaction, respectively. The excellent hydrophilicity of the PS‐b‐PHEMA membrane is not changed by thermal annealing. The chemical postmodification using EI is associated with a loss of hydrophilicity with increasing conversion. %0 journal article %@ 0926-860X %A Halder, K.,Bengtson, G.,Filiz, V.,Abetz, V. %D 2018 %J Applied Catalysis A %N %P 178-188 %R doi:10.1016/j.apcata.2018.02.004 %T Catalytically active (Pd) nanoparticles supported by electrospun PIM-1: Influence of the sorption capacity of the polymer tested in the reduction of some aromatic nitro compounds %U https://doi.org/10.1016/j.apcata.2018.02.004 %X Microfibers of the first so-called polymer of intrinsic microporosity (PIM-1) were prepared by electrospinning 10 wt.% PIM-1 in tetrachloroethane and used as immobilized supports for catalytic reactions. Solutions with varied concentrations of palladium diacetate (PdAc2) were coated on electrospun PIM-1 to show that PIM-1 is a superior catalyst supporting material with a high surface per weight ratio. Palladium (Pd) nanoparticles (NPs) were produced via the reduction of the PdAc2 with ethanol followed by subsequent thermal treatment for durably fixing the NPs on the fibers. A comparison of the catalytic activity of PIM-1 supported PdNPs was made with that of similarly produced electrospun nanofibers of polyacrylonitrile (PAN) and polyimide (6FDA-6FpDA) with catalytic PdNPs.,The morphology of the electrospun fibers and the distribution of the Pd nanoparticles on the outer surface of the fibers were determined by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) analysis of the cross section of the fibers showed the distribution of PdNPs across the fiber with a slight excess on the outer surface of the fibers. The nanoparticles (NPs) supported by the electrospun polymers catalyzed the reduction of different aromatic nitro compounds to their corresponding amino derivatives. The kinetics of the reduction reactions were monitored by ultraviolet-visible (UV-Vis) spectroscopy. Results showed that the PdNPs supported by electrospun PIM-1 fiber possessed high activity in the reduction reaction with an only slight dependence on the fiber diameter in the case of p-nitrophenol, while in the case of the dinitro compounds the dependence of the kinetics on the fiber diameter was more pronounced. The catalytic tests on two dinitro compounds proved the higher sorption of PIM-1 for p-nitrophenol is responsible for the higher catalytic activity of PIM-1 based catalytic nanofiber mats. These results clearly show that the catalytic activity of the PIM-1 fiber mats is higher compared to the fiber mats from PAN or 6FDA-6FpDA in the case of small reactants, which is mainly due to the fact that the PdNPs are also formed within the microporous PIM-1 fibers, while this is not the case for the other more dense fibers, where the catalytic particles are located only on the outer surface. %0 journal article %@ 2073-4360 %A Khan, M.M.,Halder, K.,Shishatskiy, S.,Filiz, V. %D 2018 %J Polymers %N 2 %P 221 %R doi:10.3390/polym10020221 %T Synthesis and Crosslinking of Polyether-Based Main Chain Benzoxazine Polymers and Their Gas Separation Performance %U https://doi.org/10.3390/polym10020221 2 %X The poly(ethylene glycol)-based benzoxazine polymers were synthesized via a polycondensation reaction between Bisphenol-A, paraformaldehyde, and poly(ether diamine)/(Jeffamine®). The structures of the polymers were confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR), indicating the presence of a cyclic benzoxazine ring. The polymer solutions were casted on the glass plate and cross-linked via thermal treatment to produce tough and flexible films without using any external additives. Thermal properties and the crosslinking behaviour of these polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Single gas (H2, O2, N2, CO2, and CH4) transport properties of the crosslinked polymeric membranes were measured by the time-lag method. The crosslinked PEG-based polybenzoxazine membranes show improved selectivities for CO2/N2 and CO2/CH4 gas pairs. The good separation selectivities of these PEG-based polybenzoxazine materials suggest their utility as efficient thin film composite membranes for gas and liquid membrane separation technology. %0 journal article %@ 2077-0375 %A Khan, M.M.,Shishatskiy, S.,Filiz, V. %D 2018 %J Membranes %N 1 %P 1 %R doi:10.3390/membranes8010001 %T Mixed Matrix Membranes of Boron Icosahedron and Polymers of Intrinsic Microporosity (PIM-1) for Gas Separation %U https://doi.org/10.3390/membranes8010001 1 %X This work reports on the preparation and gas transport performance of mixed matrix membranes (MMMs) based on the polymer of intrinsic microporosity (PIM-1) and potassium dodecahydrododecaborate (K2B12H12) as inorganic particles (IPs). The effect of IP loading on the gas separation performance of these MMMs was investigated by varying the IP content (2.5, 5, 10 and 20 wt %) in a PIM-1 polymer matrix. The derived MMMs were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), single gas permeation tests and sorption measurement. The PIM1/K2B12H12 MMMs show good dispersion of the IPs (from 2.5 to 10 wt %) in the polymer matrix. The gas permeability of PIM1/K2B12H12 MMMs increases as the loading of IPs increases (up to 10 wt %) without sacrificing permselectivity. The sorption isotherm in PIM-1 and PIM1/K2B12H12 MMMs demonstrate typical dual-mode sorption behaviors for the gases CO2 and CH4. %0 journal article %@ 1022-1336 %A Eggers, S.,Abetz, V. %D 2018 %J Macromolecular Rapid Communications %N 7 %P 1700683 %R doi:10.1002/marc.201700683 %T Hydroperoxide Traces in Common Cyclic Ethers as Initiators for Controlled RAFT Polymerizations %U https://doi.org/10.1002/marc.201700683 7 %X Herein, a reversible addition–fragmentation chain transfer (RAFT) polymerization is introduced for reactive monomers like N-acryloylpyrrolidine or N,N-dimethylacrylamide working without a conventional radical initiator. As a very straightforward proof of principle, the method takes advantage of the usually inconvenient radical-generating hydroperoxide contaminations in cyclic ethers like tetrahydrofuran or 1,4-dioxane, which are very common solvents in polymer sciences. The polymerizations are surprisingly well controlled and the polymers can be extended with a second block, indicating their high livingness. “Solvent-initiated” RAFT polymerizations hence prove to be a feasible access to tailored materials with minimal experimental effort and standard laboratory equipment, only requiring the following ingredients: hydroperoxide-contaminated solvent, monomer, and RAFT agent. In other respects, however, the potential coinitiating ability of the used solvent is to be considered when investigating the kinetics of RAFT polymerizations or aiming for the synthesis of high-livingness polymers, e.g., multiblock copolymers. %0 journal article %@ 0887-624X %A Eggers, S.,Eckert, T.,Abetz, V. %D 2018 %J Journal of Polymer Science A %N 4 %P 399-411 %R doi:10.1002/pola.28906 %T Double thermoresponsive block–random copolymers with adjustable phase transition temperatures: From block-like to gradient-like behavior %U https://doi.org/10.1002/pola.28906 4 %X Stimuli-responsive block–random copolymers are very useful “smart” materials as their switching behavior can be tuned by simply adjusting the composition of the random copolymer block. Because of that, we synthesized double thermoresponsive poly(N-acryloylpyrrolidine)-block-poly(N-acryloylpiperidine-co-N-acryloylpyrrolidine) (PAPy-b-P(APi-co-APy)) copolymers via reversible addition fragmentation chain transfer (RAFT) polymerization and investigated their temperature-induced self-assembly in aqueous solution. By varying the APi/APy ratio in the random copolymer block, its phase transition temperature (PTT1) can indeed be precisely adjusted while the temperature-induced collapse upon heating leads to a fully reversible well-defined micellization. By making the two blocks compositionally similar to more than 60%, the polymers' mechanistic thermoresponsiveness can furthermore be changed from block-like to rather gradient-like behavior. This means the micellization onset at PTT1 and the corona collapse at the PTT of the more hydrophilic pure PAPy block (PTT2) overlap resulting in one single broad transition. This work thus contributes to the detailed understanding of design, synthesis and mechanistic behavior of tailored “on-demand” switchable materials. %0 journal article %@ 2077-0375 %A Bucher, T.,Filiz, V.,Abetz, C.,Abetz, V. %D 2018 %J Membranes %N 3 %P 57 %R doi:10.3390/membranes8030057 %T Formation of Thin, Isoporous Block Copolymer Membranes by an Upscalable Profile Roller Coating Process - A Promising Way to Save Block Copolymer %U https://doi.org/10.3390/membranes8030057 3 %X In this work we present a method to manufacture flat sheet membranes with a thin isoporous block copolymer (BCP) layer (thickness <3 µm) by profile roller coating (breadth: 30 cm) on top of a porous support membrane. Highly diluted BCP-solutions were used for this coating process. While we cast membranes with dimensions of 30 cm × 50 cm in this work, the procedure can easily be extended to endless dimensions in this roll to roll (R2R) process. The method offers the possibility to save >95% of BCP raw material compared to common doctor blade casting, by strongly decreasing the layer thickness to below 3 µm in combination with a highly open substructure. Additionally, we report a straightforward method to investigate the influence of the solvent evaporation time between coating and precipitation (phase inversion) on the membrane morphology using one sample only, which also ensures that all other influencing parameters remain constant. %0 journal article %@ 2077-0375 %A Noor, N.,Koll, J.,Scharnagl, N.,Abetz, C.,Abetz, V. %D 2018 %J Membranes %N 3 %P 54 %R doi:10.3390/membranes8030054 %T Hollow Fiber Membranes of Blends of Polyethersulfone and Sulfonated Polymers %U https://doi.org/10.3390/membranes8030054 3 %X Hollow fiber membranes (HFM) are fabricated from blend solutions of a polyethersulfone (PESU) with a sulfonated PESU (sPESU) or a sulfonated polyphenylenesulfone (sPPSU). The influence of different additives in the dope solution and different bore fluids on the HFM are studied. The addition of poly(sodium 4-styrene sulfonate) (PSSNa)/ethylene glycol (EG) to the dope solution results in an increased water flux of the HFM compared to its counterparts without this additive system. The morphology of the hollow fibers is examined by scanning electron microscopy (SEM). The inner surface of the hollow fibers is studied by X-ray photoelectron spectroscopy (XPS), and it is found that water permeation through the hollow fiber membranes is facilitated due to the change in morphology upon the addition of the PSSNa/EG additive system, but not by the presence of hydrophilic sulfonic acid groups on the membrane surface. %0 journal article %@ 2073-4360 %A Weigelt, F.,Georgopanos, P.,Shishatskiy, S.,Filiz, V.,Brinkmann, T.,Abetz, V. %D 2018 %J Polymers %N 1 %P 51 %R doi:10.3390/polym10010051 %T Development and characterization of defect-free Matrimid mixed-matrix membranes containing activated carbon particles for gas separation %U https://doi.org/10.3390/polym10010051 1 %X In this work, mixed-matrix membranes (MMMs) for gas separation in the form of thick films were prepared via the combination of the polymer Matrimid® 5218 and activated carbons (AC). The AC particles had a mean particle size of 1.5 μm and a mean pore diameter of 1.9 nm. The films were prepared by slow solvent evaporation from casting solutions in chloroform, which had a varying polymer–AC ratio. It was possible to produce stable films with up to a content of 50 vol % of AC. Thorough characterization experiments were accomplished via differential scanning calorimetry and thermogravimetric analysis, while the morphology of the MMMs was also investigated via scanning electron microscopy. The gas transport properties were revealed by employing time-lag measurements for different pure gases as well as sorption balance experiments for the filler particles. It was found that defect free Matrimid® MMMs with AC were prepared and the increase of the filler content led to a higher effective permeability for different gases. The single gas selectivity αij of different gas pairs maintained stable values with the increase of AC content, regardless of the steep increase in the effective permeability of the pure gases. Estimation of the solubilities and the diffusivities of the Matrimid®, AC, and MMMs allowed for the explanation of the increasing permeabilities of the MMMs, with the increase of AC content by modelling. %0 journal article %@ 1811-2382 %A Derikov, Y.I.,Abetz, C.,Karpov, O.N.,Shandryuk, G.A.,Ezhov, A.A.,Kudryavtsev, Y.V.,Abetz, V. %D 2018 %J Polymer Science C %N 1 %P 240-250 %R doi:10.1134/S1811238218020054 %T Polymeric and Low-Molecular Stabilizers for Au Nanoparticles in a Diblock Copolymer Matrix %U https://doi.org/10.1134/S1811238218020054 1 %X An effect of several polymeric stabilizers on the composites based on a diblock copolymer of styrene and 2-vinyl pyridine and spherical Au nanoparticles has been studied. Among the tested substances were thiol-terminated polystyrene, thiol-terminated poly(2-vinyl pyridine), diblock copolymers of styrene with 2- and 4-vinyl pyridine, and decanethiol as a typical low molecular mass stabilizer. Thin composite films with a microphase-separated cylindrical morphology have been prepared and characterized by atomic force and scanning electron microscopy to describe the surface morphology and nanoparticle distribution in the block copolymer matrix. In all the cases, the nanoparticles were selectively positioned either within vinyl pyridine domains or at the domain boundaries. The most effective stabilization of Au nanoparticles, both regarding their location and prevention of aggregation, was provided by the diblock copolymers. %0 journal article %@ 1022-1360 %A Zainal, N.F.A.,Hein, M.,Abetz, V.,Ali, A.M.M.,Chan, C.H. %D 2018 %J Macromolecular Symposia %N 1 %P 1800083 %R doi:10.1002/masy.201800083 %T Thermal Properties and Morphology of Compatible Poly(ethylene oxide)/Natural Rubber-graft-poly(methyl methacrylate) Blends %U https://doi.org/10.1002/masy.201800083 1 %X Free standing films of blends of poly(ethylene oxide) and natural rubber‐graft‐poly(methyl methacrylate) (PEO/NR‐g‐PMMA) with 40 mol% of PMMA‐graft were prepared at different mass compositions using solution casting technique. These blends show immiscibility in the molten state as indicated by two glass transition temperatures (Tg's), which correspond relatively close to the PEO and NR‐backbone components. The assessment of Tg of the PMMA‐graft can not be made under the experimental condition (heating up to 80 °C). It is expected that the Tg of PMMA‐graft is around 100 °C. Upon cooling from the melt, PEO crystallizes and liquid‐solid phase separation takes place. At room temperature, although the blends are immiscible, results show that the amorphous phase of the blends may comprise of mixture of compatible interfacial region of PEO and PMMA‐graft. Differential scanning calorimetry (DSC) analysis was used for the qualitative assessment of the blend compatibility. The compatibility of PEO and PMMA‐graft was evaluated by change in heat capacity (ΔCp) of the glass transition of PEO and NR‐backbone in the blends. Furthermore, the crystallinity (X*) and melting temperature (Tm) of PEO in the blends at higher content of NR‐g‐PMMA are depressed, which support the Tg and ΔCp results. These findings are in agreement with PEO crystalline structure from WAXS analysis and morphological studies where the PEO spherulites show a significant change upon addition of NR‐g‐PMMA in the blends. %0 journal article %@ 0887-624X %A Halder, K.,Georgopanos, P.,Shishatskiy, S.,Filiz, V.,Abetz, V. %D 2018 %J Journal of Polymer Science A %N 24 %P 2752-2761 %R doi:10.1002/pola.29262 %T Investigation of gas transport and other physical properties in relation to the bromination degree of polymers of intrinsic microporosity %U https://doi.org/10.1002/pola.29262 24 %X In this work, the synthesis of novel polymers of intrinsic microporosity (PIMs) with different degrees of bromine substitution by a free‐radical substitution reaction was performed. The synthesized polymers were thoroughly characterized and their bromination degree was verified via nuclear magnetic resonance. The brominated PIMs were investigated by infrared spectroscopy, X‐ray diffraction, and density measurements and correlated with their gas transport properties. It was found that with an increase in the bromination degree, the synthesized PIMs exhibited a significant increase in polymer chain packing density which led to reduced fractional free volume and consequent decrease in gas diffusion and permeability coefficients. The change in permeability coefficients caused an improvement in the CO2/N2, CO2/CH4, and O2/N2 ideal permeability selectivities. %0 journal article %@ 0024-9297 %A Halder, K.,Neumann, S.,Bengtson, G.,Khan, M.M.,Filiz, V.,Abetz, V. %D 2018 %J Macromolecules %N 18 %P 7309-7319 %R doi:10.1021/acs.macromol.8b01252 %T Polymers of Intrinsic Microporosity Postmodified by Vinyl Groups for Membrane Applications %U https://doi.org/10.1021/acs.macromol.8b01252 18 %X The synthesis of a new series of polymers of intrinsic microporosity (PIM) containing vinyl groups and its performance as gas separation membranes are reported. The incorporation of the vinyl group on the spirobisindane backbone was based on the postmodification of the methylated spirobisindane polymers. Generally, the prepared polymers display good solubility and easy processability to form robust films. Characterization of the new polymers was performed by 1H and 13C nuclear magnetic resonance spectroscopy, gel permeation chromatography, infrared spectroscopy, thermal gravimetric analysis, and density measurements. The gas permeability of the CO2, N2, O2, and CH4 was measured, and selectivities for the CO2/N2 and CO2/CH4 gas pairs were calculated for the prepared polymers and compared to the values obtained from PIM-1. The two vinyl groups per repeating units enabled the modified homopolymers to engage in π-orbital overlap and conjugation with the π-orbitals of the aromatic backbone, thus leading to a reduction in CO2 permeability but surpassing the Robeson’s upper bound with CO2/N2 selectivity. The attractive CO2/N2 gas separation characteristics of the newly synthesized vinylated PIMs might be useful for postcombustion application in the capture of CO2 from power plant flue gases. The chemical versatility of the vinyl groups has been tested in two successful addition reactions (bromination and thiol–ene click). %0 journal article %@ 2218-1172 %A Kossov, A.A.,Litvinova, E.G.,Ezhov, A.A.,Khotimskii, V.S.,Shishatskii, S.M.,Buhr, K. %D 2018 %J Membrany i Membrannye Technologii %N 6 %P 399-405 %R doi:10.1134/S2218117218060068 %T Copolymers from 1-(3,3,3-Trifluoropropyldimethylsilyl)-1-propyne and 1-Trimethylsilyl-1-propyne as Membrane Materials for the Separationof Gas Mixtures Containing Hydrocarbons %U https://doi.org/10.1134/S2218117218060068 6 %X In this study fluorine-containing copolymers from 1-trimethylsilyl-1-propyne and its F-containing analog – 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne of different composition and geometric structure were obtained. The produced polymers combine resistance to hydrocarbons of different types with high permeability coefficients and high selectivity of n-butane separation from its mixture with non-condensable hydrocarbon – methane. High micro porosity of the copolymers is confirmed by the results of pore volume and pore surface area investigation by low-temperature sorption of nitrogen and the investigation of film surface via atomic force microscopy (AFM). Polymer micro porosity, which has an effect on transport properties of the copolymers is determined by both copolymer composition and its microstructure, which is formed at the stage of polymer synthesis via particular catalyst system. Particularly, copolymers produced by TaCl5–Ph3Bi catalyst exhibit greater pore size and larger pore surface area, compared to copolymers with similar TMSP content, formed by NbCl5–Ph3SiH system. The high gas-transport parameters of the obtained copolymers as well as their selectivity of hydrocarbon vapor separation from gas mixtures together with high resistance against hydrocarbons make them promising membrane materials to be used, for example, in processes of natural gas conditioning or the separation of C3+ hydrocarbons from associated petroleum gas. %0 journal article %@ 1759-9954 %A Meis, D.,Tena, A.,Neumann, S.,Georgopanos, P.,Emmler, T.,Shishatskiy, S.,Rangou, S.,Filiz, V.,Abetz, V. %D 2018 %J Polymer Chemistry %N 29 %P 3987 %R doi:10.1039/C8PY00530C %T Thermal rearrangement of ortho-allyloxypolyimide membranes and the effect of the degree of functionalization %U https://doi.org/10.1039/C8PY00530C 29 %X Aromatic polyimides containing an ortho-allyloxy group with different ratios (in the range of 10–100%) of the ortho-allyloxy to ortho-hydroxy units were synthesized. The allyl ether synthesis was done via a post-polymerization Williamson etherification reaction. Thermally induced Claisen-rearrangement of the allyloxy-phenyl unit was conducted in the solid-state, followed by isothermal treatments at 250 °C leading to a crosslinked ortho-hydroxy containing polyimide. Further thermal annealing at 350 °C was employed to achieve a high imide-to-benzoxazole conversion, commonly described as the thermal rearrangement process (TR). The influence of the degree of modification on the crosslinking reaction as well as the imide-to-benzoxazole conversion temperature and the rate were studied by means of TG-FTIR, DSC and dielectric spectroscopy. A nearly linear change of the material properties, such as film density, d-spacing and gel-fraction, with an increasing number of allylated units was observed. Additionally, an incline of the permeability, due to an increase of the free volume elements, was observed. Moreover, the polymer chain mobility in terms of relaxation times was demonstrated to depend on the degree of allylation, which in turn led to a reduction of the TR temperature of about 80 °C compared to the pristine polyimide. The thermally induced imide-to-benzoxazole rearrangement occurred already to a large extent of 77% at 350 °C. In comparison, the pristine polymer showed only a conversion of 20%. Furthermore, the observed HPI-to-PBO conversions at 350 °C surpassed those of various other reported TR polyimides treated at even higher temperatures of 400 to 450 °C. Side-reactions and degradation that usually accompany treatments at 400 °C and above might be avoided at lower treatment temperatures of 350 °C. %0 journal article %@ 1996-1944 %A Qui, H.,Hoelken, I.,Gapeeva, A.,Filiz, V.,Adelung, R.,Baum, M. %D 2018 %J Materials %N 12 %P 2413 %R doi:10.3390/ma11122413 %T Development and Characterization of Mechanically Durable Silicone-Polythiourethane Composites Modified with Tetrapodal Shaped ZnO Particles for the Potential Application as Fouling-Release Coating in the Marine Sector %U https://doi.org/10.3390/ma11122413 12 %X Ecological considerations strongly necessitate the development of environmentally friendly antifouling paints. A promising alternative to biocide containing antifouling paints are fouling-release coatings, which are non-toxic and designed to prevent permanent attachment of marine organisms to the surface, due to their low surface energy. However, these coatings suffer from insufficient mechanical properties, which make them unsuitable for mechanically stressed surfaces e.g., on ship hulls. To overcome those obstacles, polydimethylsiloxane (PDMS)-polythiourethane (PTU) composites modified with tetrapodal shaped micro-nano ZnO particles (t-ZnO) were produced and characterized by evaluating the surface energy, mechanical properties, and fouling-release performance. Among all variations, PTU/1 wt.% PDMS composites with 1 wt.% t-ZnO particles possess superior properties for applications as fouling-release coatings for maritime purposes. %0 journal article %@ 1931-7573 %A Aliyev, E.M.,Khan, M.M.,Nabiyev, A.M.,Alosmanov, R.M.,Bunyad-zadeh, I.A.,Shishatskiy, S.,Filiz, V. %D 2018 %J Nanoscale Research Letters %N %P 359 %R doi:10.1186/s11671-018-2771-3 %T Covalently Modified Graphene Oxide and Polymer of Intrinsic Microporosity (PIM-1) in Mixed Matrix Thin-Film Composite Membranes %U https://doi.org/10.1186/s11671-018-2771-3 %X In this study, mixed matrix membranes (MMMs) consisting of graphene oxide (GO) and functionalized graphene oxide (FGO) incorporated in a polymer of intrinsic microporosity (PIM-1) serving as a polymer matrix have been fabricated by dip-coating method, and their single gas transport properties were investigated. Successfully surface-modified GOs were characterized by Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The effect of FGO loading on MMM morphology and performance was investigated by varying the FGO content in polymer matrix from 9 to 84 wt.%. Use of high FGO content in the polymer matrix helped to reveal difference in interaction of functionalized fillers with PIM-1 and even to discuss the change of FGO stiffness and filler alignment to the membrane surface depending on functional group nature. %0 journal article %@ 2077-0375 %A Escorihuela, S.,Valero, L.,Tena, A.,Shishatskiy, S.,Escolastico, S.,Brinkmann, T.,Serra, J.M. %D 2018 %J Membranes %N 4 %P 128 %R doi:10.3390/membranes8040128 %T Study of the Effect of Inorganic Particles on the Gas Transport Properties of Glassy Polyimides for Selective CO2 and H2O Separation %U https://doi.org/10.3390/membranes8040128 4 %X Three polyimides and six inorganic fillers in a form of nanometer-sized particles were studied as thick film solution cast mixed matrix membranes (MMMs) for the transport of CO2, CH4, and H2O. Gas transport properties and electron microscopy images indicate good polymer-filler compatibility for all membranes. The only filler type thatdemonstrated good distribution throughout the membrane thickness at 10 wt.% loading was BaCe0.2Zr0.7Y0.1O3 (BCZY). The influence of this filler on MMM gas transport properties was studied in detail for 6FDA-6FpDA in a filler content range from one to 20 wt.% and for Matrimid® and P84® at 10 wt.% loading. The most promising result was obtained for Matrimid®—10 wt.% BCZY MMM, which showed improvement in CO2 and H2O permeabilities accompanied by increased CO2/CH4 selectivity and high water selective membrane at elevated temperatures without H2O/permanent gas selectivity loss. %0 journal article %@ 1811-2382 %A Derikov, Y.I.,Abetz, C.,Shandryuk, G.A.,Talroze, R.V.,Ezhov, A.A.,Abetz, V.,Kudryavtsev, Y.V.,Osipov, M.A. %D 2018 %J Polymer Science C %N 1 %P 78-85 %R doi:10.1134/S1811238218010034 %T Stabilization of Gold Nanospheres and Nanorods in Diblock Copolymers of Styrene and Vinylpyridine %U https://doi.org/10.1134/S1811238218010034 1 %X Composites based on microphase-separated diblock copolymers of styrene with vinylpyridine and gold nanoparticles, in which the block copolymers play simultaneously both the role of a stabilizer preventing the aggregation of nanoparticles and a matrix providing their selective arrangement within domains of the predefined type, are obtained for the first time. The suggested approach implies no use of additional stabilizers and is efficient for both initially organic dispersed small (~5 nm) spheres and hydrasols of larger (9 × 30 nm) rodlike nanoparticles. Nanospheres are introduced into the composites via replacement of a labile stabilizer used in synthesis with the diblock copolymer, while nanorods synthesized in aqueous media by the two-stage method are incorporated via phase transfer mediated by the diblock copolymer. Films capable of microphase separation leading to the formation of vinylpyridine cylindrical domains with a diameter of tens nanometers are spin-coated from the obtained composites. The content of nanoparticles in the composites is up to 5 wt %; they are dispersed and arranged predominantly within vinylpyridine domains, with nanospheres being localized near domain boundaries, while nanorods being mainly oriented perpendicularly to the axis of cylinders. %0 journal article %@ 1433-7851 %A Lauterbach, F.,Rubens, M.,Abetz, V.,Junkers, T. %D 2018 %J Angewandte Chemie - International Edition %N 43 %P 14260-14234 %R doi:10.1002/anie.201809759 %T Ultrafast PhotoRAFT Block Copolymerization of Isoprene and Styrene Facilitated through Continuous‐Flow Operation %U https://doi.org/10.1002/anie.201809759 43 %X Polymers made from isoprene and styrene resemble an important class of synthetic macromolecules found in a wide range of everyday commodity products. Their synthesis is usually limited to radical emulsion or anionic polymerization. Herein, we report on ultrafast photoiniferter reversible addition‐fragmentation chain transfer (RAFT) polymerization of isoprene and styrene in a continuous‐flow microreactor. The cooperative action of a high photoinitiation efficiency and use of elevated temperatures considerably reduces the reaction times to less than half an hour to give high monomer conversions, allowing for the first time polyisoprene to be yielded from controlled radical polymerization in high definition and reasonable reaction times. High chain‐end fidelities are maintained and block copolymers were prepared including a polystyrene‐block‐polyisoprene‐block‐polystyrene (PS‐b‐PI‐b‐PS) triblock copolymer. %0 journal article %@ 1022-1352 %A Haenelt, T.G.,Abetz, C.,Abetz, V. %D 2018 %J Macromolecular Chemistry and Physics %N 24 %P 1800383 %R doi:10.1002/macp.201800383 %T Morphological Control Over Three- and Four-Phase Superstructures in Blends of Asymmetric ABC and BAC Triblock Terpolymers %U https://doi.org/10.1002/macp.201800383 24 %X The versatile and simple attainment of complex superstructures through binary blends of asymmetric polyisoprene‐block‐polystyrene‐block‐poly(methyl methacrylate) (ISM) and polystyrene‐block‐polyisoprene‐block‐poly(methyl methacrylate) (SIM) triblock terpolymers is shown. Different well‐ordered core–shell morphologies with three or four microphases as well as interchanged core‐ and shell‐forming blocks are achieved by different spatial superposition during mixing. Superstructures with three microphases are obtained by antiparallel chain orientation, when ISM and SIM chains align in opposite directions. Similarly, the respective PS, PI, and PMMA blocks are in direct superposition and mix into each other. In contrast, with parallel chain orientation, ISM and SIM chains align in the same direction. It gives rise to four microphases because here, both PI blocks do not assemble into one microdomain, but form two isolated microdomains. These observations are attributed to inverse molecular weight ratios between both blends. %0 journal article %@ 0024-9297 %A Lu, K.-Y.,Wang, H.-F.,Lin, J.-W.,Chuang, W.-T.,Georgopanos, P.,Avgeropoulos, A.,Shi, A.-C.,Ho, R.-M. %D 2018 %J Macromolecules %N 19 %P 7656-7665 %R doi:10.1021/acs.macromol.8b01643 %T Self-Alignment of Cylinder-Forming Silicon-Containing Block Copolymer Films %U https://doi.org/10.1021/acs.macromol.8b01643 19 %X Well-ordered perpendicular cylinders of star-block copolymers (BCPs) composed of polystyrene and poly(dimethylsiloxane) blocks with high aspect ratio can be achieved by using a combination of architecture effect (entropy effect) and surface air plasma treatment (enthalpy effect). An interesting morphological evolution from disordered texture to hexagonally packed cylinders with perpendicular orientation has been observed, in which perpendicular cylinders are initiated at the top surface and bottom substrate of the thin film, followed by a self-alignment process, resulting in span-thru cylinders through the thin film. The self-alignment process is systematically examined by a combination of real space imaging using transmission electron microscopy, reciprocal space imaging using grazing incidence small-angle X-ray scattering, and three-dimensional tomography. The experimental results reveal a unique mechanism for the formation of highly ordered BCP thin films via surface-induced nucleation of perpendicularly oriented cylinders followed by lateral ordering of the cylinders. This discovery provides an insight into the mechanisms of confined self-assembly of BCP for the engineering of nanostructured thin films with controlled orientation and long-range order. %0 journal article %@ 1022-1352 %A Haenelt, T.G.,Abetz, C.,Abetz, V. %D 2018 %J Macromolecular Chemistry and Physics %N 1 %P 1700241 %R doi:10.1002/macp.201700241 %T Four-Phase Morphologies in Blends of ABC and BAC Triblock Terpolymers %U https://doi.org/10.1002/macp.201700241 1 %X It is investigated how binary blends of two asymmetric triblock terpolymers with the same type of monomers but different block sequences (ABC, BAC) and different block lengths lead to three new ABAC tetrablock terpolymer like morphologies. This study ascribes the formation of four microphases to a parallel chain orientation during the blend process. Because of the resultant spatial superposition, the B-blocks of both block copolymers can mix into each other as well as both C-blocks, whereas both A-blocks form independent microphases. The self-assembly of nine blends are studied. Their morphologies depend on the blending ratio and are monitored by transmission electron microscopy and small-angle X-ray scattering. Besides single morphologies, also coexisting morphologies are obtained, indicating that different superstructures are stable within finite compositional ranges of the blends. This work demonstrates that blending of triblock terpolymers with different block sequence is another interesting way in the huge area of morphological engineering by blending of block copolymers, leading to new and even complex, tailored nanostructures. %0 journal article %@ 1996-1944 %A Rahmstorf, E.,Abetz, V. %D 2018 %J Materials %N 9 %P 1608 %R doi:10.3390/ma11091608 %T Supramolecular Networks from Block Copolymers Based on Styrene and Isoprene Using Hydrogen Bonding Motifs - Part 1: Synthesis and Characterization %U https://doi.org/10.3390/ma11091608 9 %X The combination of controlled anionic polymerization and subsequent introduction of hydrogen bonding groups was established to form thermo-reversible, supramolecular networks. Several polyisoprene-block-polystyrene-block-polyisoprene (ISI) copolymers—with polystyrene (PS) as the main block, and consequently giving the decisive material characteristics—were synthesized. The novel modification approach to post-functionalize the polyisoprene (PI) end-blocks and to introduce different motifs, which are able to form self-complementary hydrogen bonds, was attained. In the first step, hydroxylation was accomplished using 9-borabicyclo[3.3.1]nonane. Starting from the hydroxylated polymer, esterification with succinic anhydride was implemented to form an ester group with carboxylic end-group (-O-CO-CH2-CH2-COOH). In a second approach, 1,1’-carbonyldiimidazole was used as coupling agent to introduce various types of diamines (diethylenetriamine, triethylentetramine, and 2,6-diaminopyridine) to prepare urethane groups with amine end-group (-O-CO-NH-R-NH2). 1H NMR spectroscopy was used to confirm the successful synthesis and to calculate the degree of functionalization Df. Differential scanning calorimetry (DSC) showed a difference of the glass transition temperature Tg between unfunctionalized and functionalized block copolymers, but no greater influence between the different types of modification, and thus, on the Tg of the PS block. In temperature dependent FTIR spectroscopy, reversible processes were observed. %0 journal article %@ 2468-6069 %A Cao, H.,Georgopanos, P.,Capurso, G.,Pistidda, C.,Weigelt, F.,Chaudhary, A.-L.,Filiz, V.,Tseng, J.-C.,Wharmby, M.T.,Dornheim, M.,Abetz, V.,Klassen, T. %D 2018 %J Materials Today : Energy %N %P 98-107 %R doi:10.1016/j.mtener.2018.08.008 %T Air-stable metal hydride-polymer composites of Mg(NH2)2–LiH and TPX™ %U https://doi.org/10.1016/j.mtener.2018.08.008 %X Light metal hydrides are prone to react with oxygen and/or water to produce oxides and/or hydroxides leading to reduction of hydrogen capacities, and deterioration of the hydrogen storage properties. It is therefore critical to address these issues when the materials are to be exposed to air or moisture. In this work, the combination of light metal hydrides, Mg(NH2)2–nLiH with polymethylpentene (TPX™), an air/moisture protective barrier is presented. It was found that the fabricated composites exhibit significant improvement of the metal hydrides stability in air. No oxidation reactions in air can be proven even after air exposure for 90 min. Extending the air-exposure time to 12 h, the reversible hydrogen capacities of these composites are much higher and more stable than they are in the case of the pure metal hydrides. In comparison to the pure metal hydrides, the composites retain the same hydrogen loading capacities and kinetic properties, with respect to the metal hydrides contents. Further, in situ synchrotron radiation powder X-ray radiation diffraction (SR-PXRD) experiments reveal that the thermal decomposition reaction pathways of the 90 min air-exposed composites are the same under air or H2 atmosphere. Moreover, morphology analysis confirms that the metal hydrides remain stable in the polymeric matrix and the three-dimensional integrity is retained, even after performing tens of de/re-hydrogenation cycles. The present study shows a promising way to fabricate air-stable metal hydride-polymer composite hydrogen storage materials that can be handled in ambient conditions. %0 journal article %@ 1944-8244 %A Rahman, M.M.,Abetz, C.,Shishatskiy, S.,martin, J.,Mueller, A.J.,Abetz, V. %D 2018 %J ACS Applied Materials and Interfaces %N 31 %P 26733-26744 %R doi:10.1021/acsami.8b09259 %T CO2 Selective PolyActive Membrane: Thermal Transitions and Gas Permeance as a Function of Thickness %U https://doi.org/10.1021/acsami.8b09259 31 %X It is generally accepted that the melting point of a semicrystalline polymer is associated with the thickness of the crystalline lamellae (Gibbs–Thomson equation). In this study, a commercially available multiblock copolymer PolyActive composed of 77 wt % of poly(ethylene glycol terephthalate) and 23 wt % of poly(butylene terephthalate) was dip-coated on top of a multilayer microporous support. The thickness was changed between 0.2 and 8 μm using coating solutions containing 0.75–7.5 wt % PolyActive. The surface temperature of the membrane during dip-coating was monitored using an infrared camera. Single gas permeances of N2, H2, CH4, and CO2 were measured between 20 and 80 °C at temperature steps of 2 °C. Spherulitic superstructures composed of radially directed lamellae were observed in the polarized light microscope in the prepared membranes. Atomic force microscopy studies showed that the thickness of the crystalline lamellae was in the order of 10 nm or 0.01 μm at the surface of the membrane. Therefore, according to the Gibbs–Thomson equation, the melting point should not change in the thickness range 0.2–8 μm. However, the gas permeance data showed that the melting point of the polyether domains of the 0.2 μm PolyActive layer was 10 °C lower compared to that of the 8 μm layer. The results can be explained by considering that the width of many crystalline lamellae significantly reduces as a function of film thickness, thereby reducing the average fold surface free energy/lateral surface free energy ratio. %0 journal article %@ 1996-1944 %A Rahmstorf, E.,Abetz, V. %D 2018 %J Materials %N 9 %P 1688 %R doi:10.3390/ma11091688 %T Supramolecular Networks from Block Copolymers Based on Styrene and Isoprene Using Hydrogen Bonding Motifs - Part 2: Dynamic Mechanical Analysis %U https://doi.org/10.3390/ma11091688 9 %X Thermo-reversible supramolecular networks from polyisoprene-block-polystyrene-block-polyisoprene (ISI) triblock copolymers with short, functionalized polyisoprene (PI) blocks were investigated. Functional groups along the PI blocks were hydroxyl groups, ester groups with a carboxylic end-group (-O-CO-CH2-CH2-COOH), and urethane groups with an amine end-group—synthesized from various types of diamines—(-O-CO-NH-R-NH2). Dynamic mechanical analysis (DMA) was performed at temperatures above Tg of polystyrene (PS) to investigate the influence of the different functional groups, the molecular weight, and the composition of the triblock copolymers on the materials’ properties. Furthermore, comparisons to DMA results of diblock copolymers, modified in the same way, will be presented. Arising reversible and irreversible processes observed during DMA experiments will be compared to results from temperature-dependent Fourier transform infrared (FTIR) spectroscopy. For the elaborated systems, the transition from reversible, hydrogen-bonded to permanently cross-linked networks was observed at around 150 °C. %0 journal article %@ 0032-3861 %A Dami, S.,Abetz, C.,Fischer, B.,Radjabian, M.,Georgopanos, P.,Abetz, V. %D 2017 %J Polymer %N %P 376-385 %R doi:10.1016/j.polymer.2017.05.024 %T A correlation between structural features of an amphiphilic diblock copolymer in solution and the structure of the porous surface in an integral asymmetric membrane %U https://doi.org/10.1016/j.polymer.2017.05.024 %X A correlation between the pore size of isoporous block copolymer membranes produced via the combination of self-assembly with non-solvent induced phase separation (SNIPS) on one side and the macromolecular dimensions of the block copolymer in the casting solution on the other side is presented. Dilute solutions of a polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer and corresponding polystyrene (PS) and poly(4-vinylpyridine) (P4VP) homopolymers similar to the respective blocks of the diblock copolymer are investigated separately by static and dynamic light scattering (SLS, DLS) in solvent mixtures of tetrahydrofuran/N,N-dimethylformamide (THF/DMF). These measurements provide information about the size of the individual polymers in solution. Solutions of the diblock copolymer at higher concentrations are studied furthermore by small-angle X-ray scattering (SAXS) and cryo-scanning electron microscopy (cryo-SEM) in order to estimate the size of self-assembled structures in concentrated solution, as well as by scanning electron microscopy (SEM) in the final membrane. The pore radius of the selective layer in the resulting membrane obtained by SNIPS is shown to be similar to the hydrodynamic diameter of the pore forming block, as determined in dilute solution. %0 journal article %@ 2073-4360 %A Saleem, S.,Rangou, S.,Abetz, C.,Lademann, B.,Filiz, V.,Abetz, V. %D 2017 %J Polymers %N 6 %P 216 %R doi:10.3390/polym9060216 %T Block Copolymer Membranes from Polystyrene-b-poly(solketal methacrylate) (PS-b-PSMA) and Amphiphilic Polystyrene-b-poly(glyceryl methacrylate) (PS-b-PGMA) %U https://doi.org/10.3390/polym9060216 6 %X In this paper; we compare double hydrophobic polystyrene-b-poly(solketal methacrylate) (PS-b-PSMA) and amphiphilic polystyrene-b-poly(glyceryl methacrylate) (PS-b-PGMA) diblock copolymer membranes which are prepared by combining the block copolymer self-assembly in solution with a non-solvent induced phase separation (SNIPS). Diblock copolymers (i.e., PS-b-PSMA) were synthesized by sequential living anionic polymerization, whereas polystyrene-b-poly(glyceryl methacrylate) (PS-b-PGMA) were obtained by acid hydrolysis of the acetonide groups of the polysolketal methacrylate (PSMA) blocks into dihydroxyl groups (PGMA). Membrane structures and bulk morphologies were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM); respectively. The resulting PS-b-PGMA diblock copolymers produce an ordered hexagonal cylindrical pore structure during the SNIPS process, while membranes fabricated from the double hydrophobic (PS-b-PSMA) do not under similar experimental conditions. Membrane performance was evaluated by water flux and contact angle measurements. %0 journal article %@ 0376-7388 %A Halder, K.,Khan, M.M.,Gruenauer, J.,Shishatskiy, S.,Abetz, C.,Filiz, V.,Abetz, V. %D 2017 %J Journal of Membrane Science %N %P 368-382 %R doi:10.1016/j.memsci.2017.06.022 %T Blend membranes of ionic liquid and polymers of intrinsic microporosity with improved gas separation characteristics %U https://doi.org/10.1016/j.memsci.2017.06.022 %X In the present work an attempt has been made for the first time to blend polymers of intrinsic microporosity, specifically PIM-1 with the ionic liquid (IL) [C6mim][Tf2N] in order to improve the gas separation properties of PIM membranes. The blend membrane led to a slightly reduced permeability and improved the selectivity. However, due to the lack of compatibility between PIM-1 and the IL, the polarity of PIM-1 had to be tuned. Blending and chemical modifications of PIM-1 were studied to achieve a good distribution of the IL in the polymer matrix. The first method included physical blending of PIM-1 with poly(ethylene glycol) (PEG) as compatibilizer and the second method included copolymerization of PIM-1 monomers with a PEG containing anthracene maleimide comonomer (CO). The copolymerization technique yielded better polymer-IL compatibility in the IL concentration range 2.5 – 10 wt% compared to the blends of PIM-1 with PEG and IL. The incorporation of the IL into the copolymer of PIM-1 (PIM-COP) matrix resulted in an improvement of CO2 / N2 selectivity from 19 to 30 at 30 °C, in combination with a relatively high CO2 permeability coefficient (above 800 Barrer). The studied polymer-IL composites are good candidates for the use as selective layer materials in thin film composite membranes aimed at e.g. post-combustion gas separation. %0 journal article %@ 2077-0375 %A Bengtson, G.,Neumann, S.,Filiz, V. %D 2017 %J Membranes %N 2 %P 28 %R doi:10.3390/membranes7020028 %T Membranes of Polymers of Intrinsic Microporosity (PIM-1) Modified by Poly(ethylene glycol) %U https://doi.org/10.3390/membranes7020028 2 %X Until now, the leading polymer of intrinsic microporosity PIM-1 has become quite famous for its high membrane permeability for many gases in gas separation, linked, however, to a rather moderate selectivity. The combination with the hydrophilic and low permeable poly(ethylene glycol) (PEG) and poly(ethylene oxides) (PEO) should on the one hand reduce permeability, while on the other hand enhance selectivity, especially for the polar gas CO2 by improving the hydrophilicity of the membranes. Four different paths to combine PIM-1 with PEG or poly(ethylene oxide) and poly(propylene oxide) (PPO) were studied: physically blending, quenching of polycondensation, synthesis of multiblock copolymers and synthesis of copolymers with PEO/PPO side chain. Blends and new, chemically linked polymers were successfully formed into free standing dense membranes and measured in single gas permeation of N2, O2, CO2 and CH4 by time lag method. As expected, permeability was lowered by any substantial addition of PEG/PEO/PPO regardless the manufacturing process and proportionally to the added amount. About 6 to 7 wt % of PEG/PEO/PPO added to PIM-1 halved permeability compared to PIM-1 membrane prepared under similar conditions. Consequently, selectivity from single gas measurements increased up to values of about 30 for CO2/N2 gas pair, a maximum of 18 for CO2/CH4 and 3.5 for O2/N2. %0 journal article %@ 1463-9076 %A Bey, A.,Dreyer, O.,Abetz, V. %D 2017 %J Physical Chemistry Chemical Physics %N 24 %P 15924-15932 %R doi:10.1039/c7cp02651j %T Thermodynamic analysis of alkali metal complex formation of polymer-bonded crown ether %U https://doi.org/10.1039/c7cp02651j 24 %X The complex formation of two crown ethers with colored alkali metal salts was investigated by UV/Vis spectroscopy. Complexation was accomplished with free benzo-15-crown-5 (B15C5) and 15-crown-5 bonded to a diblock copolymer (Poly15C5). The diblock copolymer was synthesized by two controlled polymerization techniques and copper(I)-catalyzed azide–alkyne cycloaddition. Depending on the inserted cation, 1:1- or 1:2-complexes are formed. A significant difference of the stability constants was determined by concentration dependence solvent extraction with sodium or potassium salt. For Poly15C5 the stability constants increase for both salts compared to the stability constants of B15C5, which suggests a more effective complexation. Evaluation of the thermodynamics (ΔH, ΔS, ΔG) of cation complexation was achieved by temperature dependence phase extraction on the basis of established thermodynamic equations. Remarkably, in all cases the entropic gain seems to be the major propulsion facilitating the complexation between alkali metal salts and crown ethers. Indeed, by using Poly15C5 a more pronounced dependency of enthalpy and entropy on the complex formation is calculated. %0 journal article %@ 1759-9954 %A Georgopanos, P.,Lo, T.-Y.,Ho, R.-M.,Avgeropoulos, A. %D 2017 %J Polymer Chemistry %N 5 %P 843-850 %R doi:10.1039/C6PY01768A %T Synthesis, molecular characterization and self-assembly of (PS-b-PDMS)n type linear (n = 1, 2) and star (n = 3, 4) block copolymers %U https://doi.org/10.1039/C6PY01768A 5 %X Well-defined linear (n = 1, 2) and star (n = 3, 4) architecture [polystyrene-b-poly(dimethylsiloxane)]n or (PS-b-PDMS)n block copolymers were synthesized by anionic polymerization and using various chlorosilanes as linking agents. The self-assembly of the novel synthesized copolymers revealed that microphase separation for the star-block copolymers is significantly influenced by entropy constraints due to the increased number of junction points. %0 journal article %@ 2045-2322 %A Georgopanos, P.,Schneider, G.A.,Dreyer, A.,Handge, U.A.,Filiz, V.,Feld, A.,Yilmaz, E.D.,Krekeler, T.,Ritter, M.,Weller, H.,Abetz, V. %D 2017 %J Scientific Reports %N %P 7314 %R doi:10.1038/s41598-017-07521-0 %T Exceptionally strong, stiff and hard hybrid material based on an elastomer and isotropically shaped ceramic nanoparticles %U https://doi.org/10.1038/s41598-017-07521-0 %X In this work the fabrication of hard, stiff and strong nanocomposites based on polybutadiene and iron oxide nanoparticles is presented. The nanocomposites are fabricated via a general concept for mechanically superior nanocomposites not based on the brick and mortar structure, thus on globular nanoparticles with nanosized organic shells. For the fabrication of the composites oleic acid functionalized iron oxide nanoparticles are decorated via ligand exchange with an α,ω-polybutadiene dicarboxylic acid. The functionalized particles were processed at 145 °C. Since polybutadiene contains double bonds the nanocomposites obtained a crosslinked structure which was enhanced by the presence of oxygen or sulfur. It was found that the crosslinking and filler percolation yields high elastic moduli of approximately 12–20 GPa and hardness of 15–18 GPa, although the polymer volume fraction is up to 40%. We attribute our results to a catalytically enhanced crosslinking reaction of the polymer chains induced by oxygen or sulfur and to the microstructure of the nanocomposite. %0 journal article %@ 0032-3861 %A Lin, T.-C.,Yang, K.-C.,Georgopanos, P.,Avgeropoulos, A.,Ho, R.-M. %D 2017 %J Polymer %N %P 360-367 %R doi:10.1016/j.polymer.2017.04.045 %T Gyroid-structured nanoporous polymer monolith from PDMS-containing block copolymers for templated synthesis %U https://doi.org/10.1016/j.polymer.2017.04.045 %X Herein, we aim to develop a simple method for the fabrication of well-ordered nanoporous materials from polystyrene-block-poly(dimethylsiloxane) (PS-PDMS) diblock copolymer. By taking advantage of the intrinsic strong segregation strength between PS and PDMS, gyroid-structured PS-PDMS can be simply acquired from initially lamellae-forming PS-PDMS (i.e., PS-PDMS with almost equal volume fractions for the two blocks) by using solution casting with PS selective solvent. With the high etching selectivity of the constituted blocks, nanoporous PS materials with gyroid-structured nanochannels can be obtained from self-assembled PS-PDMS by selectively etching the PDMS block using hydrofluoric acid. The fabricated nanoporous PS can be used as a template for controlled synthesis followed by removal of the PS to obtain various types of nanoporous materials including organics (such as epoxy) and inorganics (such as SiO2 and Ni) with well-defined gyroid textures. %0 journal article %@ 1022-1352 %A Radjabian, M.,Abetz, C.,Fischer, B.,Meyer, A.,Lademann, B.,Abetz, V. %D 2017 %J Macromolecular Chemistry and Physics %N 13 %P 1600587 %R doi:10.1002/macp.201600587 %T Structure Formation of Binary Blends of Amphiphilic Block Copolymers in Solution and in Bulk %U https://doi.org/10.1002/macp.201600587 13 %X The self-assembly and structure formation in binary blends of asymmetric polystyrene-block-poly(4-vinylpyridine) diblock copolymers in different solvent systems and the bulk morphology of the blend films are studied by using dynamic light scattering, small-angle X-ray scattering, and transmission electron microscopy. In dilute solutions, the chains of pure diblock copolymers or binary blends of diblock copolymers having similar or different molecular weights remain as unimers, form common micelles in selective solvents or form unimers in coexistence with micelles in slightly selective solvents or solvent mixtures. The blends show mixing of the chemically similar blocks in the blend films and solutions at high concentrations. A single-phase with common spherical morphology is formed in the blend films similar with the morphology of the individual components in the pure state. The characteristic length scale of the blends depends on the number average molecular weight following the typical scaling behavior of a strongly segregated block copolymer. %0 journal article %@ 0266-3538 %A Georgopanos, P.,Eichner, E.,Filiz, V.,Handge, U.A.,Schneider, G.A.,Heinrich, S.,Abetz, V. %D 2017 %J Composites Science and Technology %N %P 73-82 %R doi:10.1016/j.compscitech.2017.04.017 %T Improvement of mechanical properties by a polydopamine interface in highly filled hierarchical composites of titanium dioxide particles and poly(vinyl butyral) %U https://doi.org/10.1016/j.compscitech.2017.04.017 %X In this work, the preparation and properties of hierarchical composites of titanium dioxide (TiO2) particles (rutile modification) and poly(vinyl butyral) (PVB) are discussed. The volume fraction of the ceramic particles was approximately 60%. Two types of composites with different fillers were examined, i.e. TiO2 particles with and without a thin coating of polydopamine (PDA). A variety of characterization methods was applied in order to analyze the properties of the particles and the composites. Infrared spectroscopy is used to verify the functionalization of the particles with a thin polydopamine layer. Thermal analysis provides information on the thermal stability and the degree of functionalization of the coated particles and the composites. Scanning electron microscopy investigations reveal that the functionalized TiO2 particles with PDA form larger agglomerates which enable the coating of the TiO2 particles with PVB via the spouted bed technique. Nanoindentation experiments show that the final hierarchical composite material with the use of non-coated TiO2 particles exhibits a hardness of 0.75 ± 0.04 GPa and a Young's modulus of 29.5 ± 1.0 GPa. The composites containing polydopamine coated TiO2 particles show an increase of approximately 40% in hardness and 25% in Young's modulus in comparison to the composites with uncoated TiO2. %0 journal article %@ 1944-8244 %A Radjabian, M.,Abetz, C.,Fischer, B.,Meyer, A.,Abetz, V. %D 2017 %J ACS Applied Materials and Interfaces %N 37 %P 31224-31234 %R doi:10.1021/acsami.6b15199 %T Influence of Solvent on the Structure of an Amphiphilic Block Copolymer in Solution and in Formation of an Integral Asymmetric Membrane %U https://doi.org/10.1021/acsami.6b15199 37 %X Nanoporous membranes with tailored size pores and multifunctionality derived from self-assembled block copolymers attract growing interest in ultrafiltration. The influence of the structure of block copolymer in the membrane casting solution on the formation of integral asymmetric isoporous block copolymer membranes using the nonsolvent induced phase separation process (NIPS) has been one of the long-standing questions in this research area. In this work we studied the principal role of the solvent on the micellization and self-assembly of asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers by using a combination of dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). Our results indicate a significant effect of the solvent selectivity on the optimal casting concentration and solution structure. In addition, morphological characterization of the resulting membranes demonstrates considerable influence of the solvent system on the ordering and uniformity of the pores and pore characteristics in the separation layer as well as porous substructure of the final membranes. %0 journal article %@ 2196-7350 %A Sankhala, K.,Koll, J.,Radjabian, M.,Handge, U.A.,Abetz, V. %D 2017 %J Advanced Materials Interfaces %N 7 %P 1600991 %R doi:10.1002/admi.201600991 %T A Pathway to Fabricate Hollow Fiber Membranes with Isoporous Inner Surface %U https://doi.org/10.1002/admi.201600991 7 %X A novel inside isoporous hollow fiber membrane is prepared using the dry-jet wet spinning technique. Subsequently, the self-assembly of block copolymer in combination with nonsolvent-induced phase separation takes place in the lumen side of the spun hollow fibers with a diameter of less than 1 mm leading to technologically favored inside membranes for water purification. %0 journal article %@ 0032-3861 %A Schulze, M.,Handge, U.A.,Abetz, V. %D 2017 %J Polymer %N %P 400-412 %R doi:10.1016/j.polymer.2016.12.005 %T Preparation and characterisation of open-celled foams using polystyrene-b-poly(4-vinylpyridine) and poly(4-methylstyrene)-b-poly(4-vinylpyridine) diblock copolymers %U https://doi.org/10.1016/j.polymer.2016.12.005 %X In this study, the potential of amphiphilic diblock copolymers on the example of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and poly(4-methylstyrene)-b-poly(4-vinylpyridine) (P4mS-b-P4VP) for producing open-celled foams was evaluated. The porous foam structure was realised by employing carbon dioxide and water as environmental-friendly blowing agents. Rheological measurements in shear and elongation revealed a similar strain-softening behaviour of the diblock copolymers in the melt state. The transient shear and elongational viscosity of the P4mS homopolymer agreed with the linear viscoelastic prediction. On the contrary, the employed PS homopolymer showed strain-hardening. The rheological behaviour of the PS and P4mS homopolymers is consistent with their foaming ability. The PS homopolymer led to a homogeneous, closed cell structure, while the P4mS homopolymer did not foam at all. Because of strain-softening in melt elongation, the PS-b-P4VP diblock copolymer generated homogeneous, open-celled foams throughout the whole sample. In contrast, the P4mS-b-P4VP diblock copolymer generated partially open-celled structures in coexistence with compact areas. In this work, it was demonstrated that the combination of carbon dioxide and water led to open-celled diblock copolymer foams even if the major component of the block copolymer generates homogeneous closed-celled foams or is not foamable, respectively. %0 journal article %@ 2365-709X %A Hauenstein, O.,Rahman, M.M.,Elsayed, M.,Krause-Rehberg, R.,Agarwal, S.,Abetz, V.,Greiner, A. %D 2017 %J Advanced Materials Technologies %N 5 %P 1700026 %R doi:10.1002/admt.201700026 %T Biobased Polycarbonate as a Gas Separation Membrane and “Breathing Glass” for Energy Saving Applications %U https://doi.org/10.1002/admt.201700026 5 %X The biobased poly(limonene carbonate) (PLimC) synthesized by catalytic copolymerization of trans-limonene oxide and CO2 unifies sustainability, carbon capture and utilization of CO2 in one material. Films of PLimC show surprisingly high gas permeation and good selectivity. Additionally, it is not only very permeable to gases, but also to light, while simultaneously being a good heat insulator and mechanically strong, representing a novel type of material that is defined here as “breathing glass.” Hence, this study investigates the gas permeation and the selectivity in detail. The selectivity of PLimC for CO2 can be understood by its high fractional free volume, which is determined by positron annihilation lifetime spectroscopy supported by simulations. The CO2 permeability of PLimC at 30 °C is 68 barrer, while the CO2/N2 selectivity is ≈19, which places PLimC in a promising position in the Robeson plot and makes it unique due to its excellent transparency and processability under ambient conditions. Based on the high permeability of PLimC to gases and light, this study discusses here a completely new potential application of light transparent, gas-permeable polymer films as “breathing glass.” %0 journal article %@ 0032-3861 %A Wittenberg, E.,Abetz, V. %D 2017 %J Polymer %N %P 304-311 %R doi:10.1016/j.polymer.2017.06.001 %T New post modification route for styrene butadiene copolymers leading to supramolecular hydrogen bonded networks - Synthesis and thermodynamic analysis of complexation %U https://doi.org/10.1016/j.polymer.2017.06.001 %X In this work we present a new and simple post modification route for styrene-butadiene copolymers using well established reactions including hydrochlorination and Steglich esterification to obtain alkyne functionalized styrene-butadiene copolymers. The alkyne linker allows the introduction of arbitrary azides into the styrene-butadiene copolymers via copper catalyzed azide alkyne cycloaddition and this leads to a toolbox of diverse functional polymers. This method gives new opportunities regarding modification strategies and is used in this work to obtain supramolecular styrene-butadiene copolymer networks by introduction of a benzoic acid derivative. This simple supramolecular motif forms temperature dependent hydrogen bonding complexes which can be quantitatively studied by FTIR spectroscopy. We found that the equilibrium constant, ΔH and ΔS are changing with temperature which can be attributed to a structural modification: the dissociation. %0 journal article %@ 0024-9297 %A Lu, K.-Y.,Lo, T.-Y.,Georgopanos, P.,Avgeropoulos, A.,Shi, A.-C.,Ho, R.-M. %D 2017 %J Macromolecules %N 23 %P 9403-9410 %R doi:10.1021/acs.macromol.7b02218 %T Orienting Silicon-Containing Block Copolymer Films with Perpendicular Cylinders via Entropy and Surface Plasma Treatment %U https://doi.org/10.1021/acs.macromol.7b02218 23 %X Controlling the orientation of nanostructured block copolymer (BCP) thin films is essential for next-generation lithography. However, obtaining BCP with perpendicular orientation remains a challenge because of the surface selectivity to the different blocks. This challenge is especially severe for silicon-containing BCPs which is notorious for its high surface energy difference between constituted blocks. Here, we demonstrate a new approach to achieve perpendicular orientation with high aspect ratio using a combination of architecture effect (entropy effect) and surface air plasma treatment (enthalpy effect). Specifically, perpendicular cylinders of star-block copolymers composed of polystyrene and poly(dimethylsiloxane) blocks can be formed from the bottom substrate to the top surface of the thin film. %0 journal article %@ 1759-9954 %A Lucht, N.,Eggers, S.,Abetz, V. %D 2017 %J Polymer Chemistry %N 7 %P 1196-1205 %R doi:10.1039/c6py01751g %T Cononsolvency in the ‘drunken’ state: the thermoresponsiveness of a new acrylamide copolymer in water–alcohol mixtures %U https://doi.org/10.1039/c6py01751g 7 %X Stimuli-responsive ‘smart’ polymers are a promising class of materials for switchable devices. In this work, we present poly[N-acryloylpiperidine-random-N-acryloylpyrrolidine] (poly[APi-r-APy]) as a novel thermoresponsive copolymer which was synthesised by reversible addition–fragmentation chain transfer (RAFT) polymerisation in a controlled manner. One of its attractive features is that the lower critical solution temperature (LCST) in aqueous solution, i.e. the temperature at which the polymer instantaneously becomes insoluble, can be freely adjusted between 3 °C and 47 °C. This adjustment is indeed extremely straightforward because the LCST of the copolymer is linearly dependent on the copolymer composition. We furthermore discuss the influence of the addition of a second ‘good’ solvent to polymer–water solutions on the thermoresponsiveness of the system. Depending on the nature of the additive, the cloud point can be shifted both upwards and downwards. Our research is focused on alcoholic additives, with systematic variation of the chemical structure of the alcohol, which resulted in the occurrence of remarkable cononsolvency effects. The results are discussed in terms of polymer–additive as well as additive–water interactions and help to gain a more detailed understanding of water interactions with amphiphilic additives and, hence, of cononsolvency phenomena. This work moreover contributes to the systematic design of switchable systems with tailored phase transition properties. %0 journal article %@ 2095-8099 %A Brinkmann, T.,Lillepaerg, J.,Notzke, H.,Pohlmann, J.,Shishatskiy, S.,Wind, J.,Wolff, T. %D 2017 %J Engineering %N 4 %P 485-493 %R doi:10.1016/J.ENG.2017.04.004 %T Development of CO2 Selective Poly(Ethylene Oxide)-Based Membranes: From Laboratory to Pilot Plant Scale %U https://doi.org/10.1016/J.ENG.2017.04.004 4 %X Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide (CO2) from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly(ethylene oxide)-containing block copolymers such as Pebax® or PolyActive™ polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActive™ polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m3(STP)·(m2·h·bar)−1 (1 bar = 105 Pa) at a carbon dioxide/nitrogen (CO2/N2) selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into flat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActive™ polymer as a membrane material for industrial-scale gas processing. %0 journal article %@ 2077-0375 %A Clodt, J.I.,Filiz, V.,Shishatskiy, S. %D 2017 %J Membranes %N 3 %P 51 %R doi:10.3390/membranes7030051 %T Perfluorinated Compounds as Test Media for Porous Membranes %U https://doi.org/10.3390/membranes7030051 3 %X We suggest a failure-free method of porous membranes characterization that gives the researcher the opportunity to compare and characterize properties of any porous membrane. This proposal is supported by an investigation of eight membranes made of different organic and inorganic materials, with nine different perfluorinated compounds. It was found that aromatic compounds, perfluorobenzene, and perfluorotoluene, used in the current study show properties different from other perfluorinated aliphatics. They demonstrate extreme deviation from the general sequence indicating the existence of π-π-interaction on the pore wall. The divergence of the flow for cyclic compounds from ideal e.g., linear compounds can be an indication of the pore dimension. %0 journal article %@ 1560-0904 %A Kossov, A.A.,Buhr, K.,Shishatskiy, S.M.,Litvinova, E.G.,Khotimskii, V.S. %D 2017 %J Polymer Science B %N 4 %P 452-458 %R doi:10.1134/S1560090417040066 %T Copolymers of 1,2-disubstituted acetylenes containing trifluoropropyl groups synthesized in the presence of NbCl5-based catalyst systems: Structure and gas-transport behavior %U https://doi.org/10.1134/S1560090417040066 4 %X Using a NbCl5-based catalyst system, random copolymers of 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne and 1-trimethylsilyl-1-propyne are synthesized in a wide range of comonomer contents. The dependences of gas-transport behavior on the composition and supramolecular organization of the copolymer are studied. Composition regions and conditions of preparing copolymers combining high permeability coefficients with resistance against nonpolar organic solvents are ascertained. The copolymers demonstrate a high selectivity in the separation of butane from a methane–butane mixture. %0 journal article %@ 2045-2322 %A Noor, N.,Koll, J.,Abetz, C.,Notzke, H.,Abetz, V. %D 2017 %J Scientific Reports %N %P 8050 %R doi:10.1038/s41598-017-08027-5 %T Continuous Production of Macroporous Films: an Alternative to Breath Figure Assembly %U https://doi.org/10.1038/s41598-017-08027-5 %X Despite the need for sophisticated instrumentation, breath figure assembly (BFA) methods are restricted to produce macroporous films on a tiny scale so far. The current study narrates the fabrication of macroporous films in hollow fiber geometry which extends to adopt the method for continuous production of isoporous surfaces from commercially available low-priced polymer materials. The fabrication of the films in the hollow fiber geometry is carried out by a co-centric quadruple orifice spinneret through which four different liquids are co-extruded simultaneously: bore fluid (to fill the lumen of the fiber), support layer solution, glycerol, and an isoporous film forming solution through the outer most orifice. The extruded entities plunge into a coagulation bath after passing a definite air gap. The implementation of the concept of diffuse-in, droplet formation, and then condense-out behavior of glycerol in a co-extrusion method of hollow fiber spinning makes macroporous film formation possible in an interminable way sidestepping the use of breath figure assembly method. Moreover, the continuous film formation by the proposed mechanism is also authenticated in flat sheet geometry by employing two casting blades in a casting machine. The structure of the films is analyzed by scanning electron microscopy (SEM). %0 journal article %@ 0024-9297 %A Tena, A.,Shishatskiy, S.,meis, D.,Wind, J.,Filiz, V.,Abetz, V. %D 2017 %J Macromolecules %N 15 %P 5839-5849 %R doi:10.1021/acs.macromol.7b01051 %T Influence of the Composition and Imidization Route on the Chain Packing and Gas Separation Properties of Fluorinated Copolyimides %U https://doi.org/10.1021/acs.macromol.7b01051 15 %X A strong effect of the chemical composition and imidization method on physical and especially on gas transport properties of polyimides was demonstrated. Two fluorinated diamines 6FpDA and bisAPAF were polymerized in different ratios, employing the fluorinated dianhydride 6FDA to get polyimides with nine different compositions. For all synthesized materials three imidization methods were used: azeotropic, thermal, and chemical. The 6FDA-6FpDA homopolymers showed significant differences in the gas transport properties, indicating the influence of the imidization route on the final properties of the polyimides. For polyimides containing bisAPAF, the chemical composition played an important role due to the exchange of the hydroxyl groups by acetate groups leading to different interchain interactions. The gas transport was mainly controlled by the chain packing for thermally and azeotropically imidized polymers with bisAPAF contents lower than 30 mol %. For bisAPAF contents above 50 mol % the gas transport was controlled by the intermolecular interactions, e.g., hydrogen bonds. %0 journal article %@ 1438-7492 %A Otto, C.,Handge, U.A.,Georgopanos, P.,Aschenbrenner, O.,Kerwitz, J.,Abetz, C.,Metze, A.-L.,Abetz, V. %D 2017 %J Macromolecular Materials and Engineering %N 4 %P 1600405 %R doi:10.1002/mame.201600405 %T Porous UHMWPE Membranes and Composites Filled with Carbon Nanotubes: Permeability, Mechanical, and Electrical Properties %U https://doi.org/10.1002/mame.201600405 4 %X Application of electric fields as a mechanism against membrane fouling is an emerging cleaning process for membranes. Sintering of ultrahigh molecular weight polyethylene powder particles decorated with multiwalled carbon nanotubes (MWCNT) is performed to produce electrically conductive porous filtration membranes. The contact of the molten particle surfaces leads to their fusion through neck formation during sintering. As the MWCNT only cover the surface of the powder particles, they form a conductive network with a high number of inter-MWCNT contacts in pathways through the polymer matrix. Membranes with an electrical conductivity of 0.9 S m−1 at a MWCNT concentration of 5.0 wt% are prepared. Additionally, a comparison of sintered and compression molded samples shows that after the heating interval, crystallization during cooling strongly influences the formation of the MWCNT network. The study reveals that electrically conductive, porous polymer membranes for microfiltration applications can be prepared using a solvent-free process. %0 journal article %@ 2073-4360 %A Eggers, S.,Abetz, V. %D 2017 %J Polymers %N 12 %P 668 %R doi:10.3390/polym9120668 %T Surfactant-Free RAFT Emulsion Polymerization of Styrene Using Thermoresponsive macroRAFT Agents: Towards Smart Well-Defined Block Copolymers with High Molecular Weights %U https://doi.org/10.3390/polym9120668 12 %X The combination of reversible addition–fragmentation chain transfer (RAFT) and emulsion polymerization has recently attracted much attention as a synthetic tool for high-molecular-weight block copolymers and their micellar nano-objects. Up to recently, though, the use of thermoresponsive polymers as both macroRAFT agents and latex stabilizers was impossible in aqueous media due to their hydrophobicity at the usually high polymerization temperatures. In this work, we present a straightforward surfactant-free RAFT emulsion polymerization to obtain thermoresponsive styrenic block copolymers with molecular weights of around 100 kDa and their well-defined latexes. The stability of the aqueous latexes is achieved by adding 20 vol % of the cosolvent 1,4-dioxane (DOX), increasing the phase transition temperature (PTT) of the used thermoresponsive poly(N-acryloylpyrrolidine) (PAPy) macroRAFT agents above the polymerization temperature. Furthermore, this cosolvent approach is combined with the use of poly(N,N-dimethylacrylamide)-block-poly(N-acryloylpiperidine-co-N-acryloylpyrrolidine) (PDMA-b-P(APi-co-APy)) as the macroRAFT agent owning a short stabilizing PDMA end block and a widely adjustable PTT of the P(APi-co-APy) block in between 4 and 47 °C. The temperature-induced collapse of the latter under emulsion polymerization conditions leads to the formation of RAFT nanoreactors, which allows for a very fast chain growth of the polystyrene (PS) block. In dynamic light scattering (DLS), as well as cryo-transmission electron microscopy (cryoTEM), moreover, all created latexes indeed reveal a high (temperature) stability and a reversible collapse of the thermoresponsive coronal block upon heating. Hence, this paper pioneers a versatile way towards amphiphilic thermoresponsive high-molecular-weight block copolymers and their nano-objects with tailored corona switchability. %0 journal article %@ 2077-0375 %A Bucher, T.,Clodt, J.I.,Grabowski, A.,Hein, M.,Filiz, V. %D 2017 %J Membranes %N 4 %P 70 %R doi:10.3390/membranes7040070 %T Colour-Value Based Method for Polydopamine Coating-Stability Characterization on Polyethersulfone Membranes %U https://doi.org/10.3390/membranes7040070 4 %X Porous polyethersulfone membranes as used in oenology were investigated in order to evaluate temperature-dependent permeances in a temperature range from 10 to 35 °C. A temperature correction factor was determined for this type of membrane to get accurate and comparable results for further developments. Moreover, the membranes were modified with a bio-inspired polydopamine coating in order to reduce fouling. The performance of the membranes could be increased with respect to permeance and flux recovery under cross-flow conditions. In order to test the applicability and stability of the coating layer, they were treated with basic and acidic cleaning agents as used in industry for fouled membranes. The chemical stability of the coating layer was studied under basic and acidic conditions, by systematic observation of the colour change of the coated membranes over treatment time. %0 journal article %@ 0032-3861 %A Kollmetz, T.,Georgopanos, P.,Handge, U.A. %D 2017 %J Polymer %N %P 68-82 %R doi:10.1016/j.polymer.2017.09.031 %T Rheology in shear and elongation and dielectric spectroscopy of polystyrene-block-poly(4-vinylpyridine) diblock copolymers %U https://doi.org/10.1016/j.polymer.2017.09.031 %X We elucidate the influence of composition (weight ratios of 89/11, 76/24 and 49/51) and morphology (spherical, cylindrical and lamellar) on the dielectric and viscoelastic properties in shear and elongation of anionically synthesized polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers in the microphase-separated state. The temperature dependence of the response in both experiments is compared. The analysis of the linear regime shows the appearance of composition (superposition of moduli) and interfacial effects caused by microphase separation (low frequency shoulder, plateau and regime for dynamic moduli and Maxwell-Wagner-Sillars polarization in dielectric experiments). In shear and extensional flows with a constant deformation rate, a pronounced strain-softening behavior in case of a cylindrical and a lamellar morphology appears. For a high weight fraction of the majority phase and a spherical morphology, respectively, strain-softening is observed to a lesser extent. Consequently, strain-softening of diblock copolymer melts can be tuned by the weight/volume ratio of the two blocks. %0 journal article %@ 2073-4360 %A Weigelt, F.,Georgopanos, P.,Shishatskiy, S.,Filiz, V.,Brinkmann, T.,Abetz, V. %D 2017 %J Polymers %N 1 %P 51 %R doi:10.3390/polym10010051 %T Development and Characterization of Defect-Free Matrimid® Mixed-Matrix Membranes Containing Activated Carbon Particles for Gas Separation %U https://doi.org/10.3390/polym10010051 1 %X In this work, mixed-matrix membranes (MMMs) for gas separation in the form of thick films were prepared via the combination of the polymer Matrimid® 5218 and activated carbons (AC). The AC particles had a mean particle size of 1.5 μm and a mean pore diameter of 1.9 nm. The films were prepared by slow solvent evaporation from casting solutions in chloroform, which had a varying polymer–AC ratio. It was possible to produce stable films with up to a content of 50 vol % of AC. Thorough characterization experiments were accomplished via differential scanning calorimetry and thermogravimetric analysis, while the morphology of the MMMs was also investigated via scanning electron microscopy. The gas transport properties were revealed by employing time-lag measurements for different pure gases as well as sorption balance experiments for the filler particles. It was found that defect free Matrimid® MMMs with AC were prepared and the increase of the filler content led to a higher effective permeability for different gases. The single gas selectivity αij of different gas pairs maintained stable values with the increase of AC content, regardless of the steep increase in the effective permeability of the pure gases. Estimation of the solubilities and the diffusivities of the Matrimid®, AC, and MMMs allowed for the explanation of the increasing permeabilities of the MMMs, with the increase of AC content by modelling. %0 journal article %@ 0032-3861 %A Rahman, M.M.,Lillepaerg, J.,Neumann, S.,Shishatskiy, S.,Abetz, V. %D 2016 %J Polymer %N %P 132-141 %R doi:10.1016/j.polymer.2016.04.024 %T A thermodynamic study of CO2 sorption and thermal transition of PolyActive™ under elevated pressure %U https://doi.org/10.1016/j.polymer.2016.04.024 %X The sorption of CO2 in two commercial grades of multiblock copolymers (PolyActive™) is investigated using a magnetic suspension balance in the temperature range 30–70 °C. The isotherms follow Henry's law when the poly(ethylene glycol) (PEG) blocks of PolyActive™ are in a molten state. A significant deviation is observed when the PEG blocks are still in a semicrystalline state. Differential scanning calorimetry (DSC) is used to study the thermal transitions of the polymers. The melting and crystallization of the PEG blocks is studied using high pressure differential scanning calorimetry in both CO2 and N2 gas environment. A substantial decrease of melting and crystallization temperatures occurs with increasing CO2 pressure. But no change occurs under N2 pressure. The observed experimental results are discussed on the basis of established thermodynamic equations reported in the literature which provide an adequate guideline to correlate the sorption isotherms with the thermal transition of the PEG blocks. %0 journal article %@ 2077-0375 %A Mushardt, H.,Mueller, M.,Shishatskiy, S.,Wind, J.,Brinkmann, T. %D 2016 %J Membranes %N 1 %P 16 %R doi:10.3390/membranes6010016 %T Detailed Investigation of Separation Performance of a MMM for Removal of Higher Hydrocarbons under Varying Operating Conditions %U https://doi.org/10.3390/membranes6010016 1 %X Mixed-matrix membranes (MMMs) are promising candidates to improve the competitiveness of membrane technology against energy-intensive conventional technologies. In this work, MMM composed of poly(octylmethylsiloxane) (POMS) and activated carbon (AC) were investigated with respect to separation of higher hydrocarbons (C3+) from permanent gas streams. Membranes were prepared as thin film composite membranes on a technical scale and characterized via scanning electron microscopy (SEM) and permeation measurements with binary mixtures of n-C4H10/CH4 under varying operating conditions (feed and permeate pressure, temperature, feed gas composition) to study the influence on separation performance. SEM showed good contact and absence of defects. Lower permeances but higher selectivities were found for MMM compared to pure POMS membrane. Best results were obtained at high average fugacity and activity of n-C4H10 with the highest selectivity estimated to be 36.4 at n-C4H10 permeance of 12 mN3/(m2·h·bar). Results were complemented by permeation of a multi-component mixture resembling a natural gas application, demonstrating the superior performance of MMM. %0 journal article %@ 1476-1122 %A Dreyer, A.,Feld, A.,Kornowski, A.,Yilmaz, E.D.,Noei, H.,Meyer, A.,Krekeler, T.,JIao, C.,Stierle, A.,Abetz, V.,Weller, H.,Schneider, G.A. %D 2016 %J Nature Materials %N %P 522-528 %R doi:10.1038/nmat4553 %T Organically linked iron oxide nanoparticle supercrystals with exceptional isotropic mechanical properties %U https://doi.org/10.1038/nmat4553 %X It is commonly accepted that the combination of the anisotropic shape and nanoscale dimensions of the mineral constituents of natural biological composites underlies their superior mechanical properties when compared to those of their rather weak mineral and organic constituents1. Here, we show that the self-assembly of nearly spherical iron oxide nanoparticles in supercrystals linked together by a thermally induced crosslinking reaction of oleic acid molecules leads to a nanocomposite with exceptional bending modulus of 114 GPa, hardness of up to 4 GPa and strength of up to 630 MPa. By using a nanomechanical model, we determined that these exceptional mechanical properties are dominated by the covalent backbone of the linked organic molecules. Because oleic acid has been broadly used as nanoparticle ligand, our crosslinking approach should be applicable to a large variety of nanoparticle systems. %0 journal article %@ 0032-3861 %A Georgopanos, P.,Handge, U.A.,Abetz, C.,Abetz, V. %D 2016 %J Polymer %N %P 279-295 %R doi:10.1016/j.polymer.2016.02.039 %T Influence of block sequence and molecular weight on morphological, rheological and dielectric properties of weakly and strongly segregated styrene-isoprene triblock copolymers %U https://doi.org/10.1016/j.polymer.2016.02.039 %X In this work, morphological, thermal, viscoelastic and dielectric properties of triblock copolymers consisting of styrene (S) and isoprene (I) blocks are discussed. SIS and ISI triblock copolymers were synthesized by sequential anionic polymerization, three of them exhibiting molecular weights below the entanglement molecular weight Me, three of them exhibiting molecular weights in the order of Me and two of them exhibiting molecular weights above Me. The objective of this work is the investigation of the influence of molecular weight and block sequence on relaxation of the block copolymer chains. Morphological investigations using small angle X-ray scattering and transmission electron microscopy studies reveal that a larger molecular weight is associated with a more pronounced microphase separation. The presence of two glass transition temperatures reveals microphase separation of the PI and PS blocks. The Fox-Flory equation was applied in order to describe the molecular weight dependence of the glass transition temperature of the polyisoprene and the polystyrene blocks. The analysis of rheological data reveals a Maxwell fluid behaviour for the weakly segregated block copolymers, whereas for the strongly segregated block copolymers a pronounced elastic behaviour at low frequencies of small amplitude shear oscillations was observed. In the intermediate regime of molecular weight, a complex viscoelastic behaviour appears. The plateau modulus View the MathML sourceGNo is influenced by the sequence of the PS and the PI blocks (SIS or ISI). Our analysis of segmental and normal mode relaxation in dielectric spectroscopy experiments show that the relaxation processes are strongly influenced by the block sequence (PI blocks tethered at one or both ends) and the molecular weight. As a result, the block sequence in triblock copolymers influences dynamical properties in the glassy state and in the melt. %0 journal article %@ 0032-3861 %A Eggers, S.,Lauterbach, F.,Abetz, V. %D 2016 %J Polymer %N %P 357-367 %R doi:10.1016/j.polymer.2016.04.066 %T Synthesis and self-assembly of high molecular weight polystyrene-block-poly[2-(N-morpholino)ethyl methacrylate]: A story about microphase separation, amphiphilicity, and stimuli-responsivity %U https://doi.org/10.1016/j.polymer.2016.04.066 %X The synthesis of polystyrene-block-poly[2-(N-morpholino)ethyl methacrylate] (PS-b-PMEMA) as a new highly amphiphilic and multiple stimuli-responsive block copolymer is presented. To achieve high molecular weights far beyond 100 kDa in a highly controlled manner (dispersities < 1.1), a synthetic route via sequential combination of anionic polymerization for the PS block and reversible addition–fragmentation chain transfer (RAFT) polymerization for the PMEMA block is used. The synthesized block copolymers are investigated regarding their microphase separation in bulk, which delivers well-ordered self-assembled bulk structures as evidenced by small-angle x-ray scattering (SAXS) and atomic force microscopy (AFM). In aqueous solution, the block copolymer self-assembles into narrowly size distributed micelles with a PMEMA corona. The stimuli-triggered micelle response towards temperature, pH, and kosmotropic as well as chaotropic salts is shown via various dynamic light scattering (DLS) experiments. Furthermore, a dependency of aggregate size on solvent composition in polymer/tetrahydrofuran/water mixtures is described. The reported findings deliver a feasible pathway to high molecular weight block copolymers with tailored chemical properties and show the potential of PS-b-PMEMA as material for mechanically demanding switchable devices. %0 journal article %@ 2046-2069 %A Lillepaerg, J.,Georgopanos, P.,Emmler, T.,Shishatskiy, S. %D 2016 %J RSC Advances %N 14 %P 11763-11772 %R doi:10.1039/c5ra22026b %T Effect of the reactive amino and glycidyl ether terminated polyethylene oxide additives on the gas transport properties of Pebax® bulk and thin film composite membranes %U https://doi.org/10.1039/c5ra22026b 14 %X This paper considers Pebax® MH 1657 as a material for the CO2/N2 separating layer in thin film composite (TFC) membranes. The CO2 permeability of Pebax® can be improved via blending with various poly(ethylene oxide) (PEO) based materials without loss of CO2/N2 selectivity. Analogous blends containing PEOs with reactive end groups have been investigated for the possibility of a network formation within the Pebax® matrix. The formation of network is possible through the reaction between two types of additives containing two reactive end groups. The thick film samples and TFC membranes were prepared from mixtures of Pebax® MH 1657, PEG DG526 and JEFFAMINE® with different molecular weights. The samples were characterized by single gas permeation measurements, DSC, and NMR. The samples with incorporated networks show improved and stable gas transport properties compared to the original polymer for both thick films and TFC membranes. %0 journal article %@ 1022-1352 %A Eggers, S.,Fischer, B.,Abetz, V. %D 2016 %J Macromolecular Chemistry and Physics %N 6 %P 735-747 %R doi:10.1002/macp.201500339 %T Aqueous Solutions of Poly[2-(N-morpholino)ethyl methacrylate]: Learning about Macromolecular Aggregation Processes from a Peculiar Three-Step Thermoresponsive Behavior %U https://doi.org/10.1002/macp.201500339 6 %X Aqueous solutions of narrowly distributed poly[2-(N-morpholino)ethyl methacrylate], a biocompatible multiple stimuli-responsive polymer, show a peculiar three-step aggregation behavior upon heating, an effect which has hitherto barely been reported for other polymers. The phenomenon is discussed in terms of mesoglobule formation (first step) as well as by an unusual distinct disruption of hydrophobic hydration (second step) and hydrogen bonding to the hydrophilic aggregate surface (third step). Macroscopic precipitation only takes place after the third step, a behavior which resembles the denaturation and limited aggregation of proteins. Furthermore, the influence of different anions along the Hofmeister series is investigated, identifying salting-out (kosmotropic) and salting-in (chaotropic) effects. As an experimental tool to monitor the thermally induced aggregate growth, dynamic light scattering is used. The reported findings might lead to a more detailed understanding of both aggregation behavior of (biological) macromolecules and mechanistic processes involved in thermoresponsivity and salt-responsivity of water soluble polymers. %0 journal article %@ 1022-1336 %A Noor, N.,Koll, J.,Radjabian, M.,Abetz, C.,Abetz, V. %D 2016 %J Macromolecular Rapid Communications %N 5 %P 414-419 %R doi:10.1002/marc.201500593 %T A Facile Method to Prepare Double-Layer Isoporous Hollow Fiber Membrane by In Situ Hydrogen Bond Formation in the Spinning Line %U https://doi.org/10.1002/marc.201500593 5 %X A double-layer hollow fiber is fabricated where an isoporous surface of polystyrene-block-poly(4-vinylpyridine) is fixed on a support layer by co-extrusion. Due to the sulfonation of the support layer material, delamination of the two layers is suppressed without increasing the number of subsequent processing steps for isoporous composite membrane formation. Electron microscope-energy-dispersive X-ray spectroscopy images unveil the existence of a high sulfur concentration in the interfacial region by which in-process H-bond formation between the layers is evidenced. For the very first time, our study reports a facile method to fabricate a sturdy isoporous double-layer hollow fiber. %0 journal article %@ 2375-2548 %A Tena, A.,Rangou, S.,Shishatskiy, S.,Filiz, V.,Abetz, V. %D 2016 %J Science Advances %N 7 %P e1501859 %R doi:10.1126/sciadv.1501859 %T Claisen thermally rearranged (CTR) polymers %U https://doi.org/10.1126/sciadv.1501859 7 %X Thermally rearranged (TR) polymers, which are considered the next-generation of membrane materials because of their excellent transport properties and high thermal and chemical stability, are proven to have significant drawbacks because of the high temperature required for the rearrangement and low degree of conversion during this process. We demonstrate that using a [3,3]-sigmatropic rearrangement, the temperature required for the rearrangement of a solid glassy polymer was reduced by 200°C. Conversions of functionalized polyimide to polybenzoxazole of more than 97% were achieved. These highly mechanically stable polymers were almost five times more permeable and had more than two times higher degrees of conversion than the reference polymer treated under the same conditions. Properties of these second-generation TR polymers provide the possibility of preparing efficient polymer membranes in a form of, for example, thin-film composite membranes for various gas and liquid membrane separation applications. %0 journal article %@ 0032-3861 %A Handge, U.A.,Wolff, M.F.H.,Abetz, V.,Heinrich, S. %D 2016 %J Polymer %N %P 337-348 %R doi:10.1016/j.polymer.2015.11.047 %T Viscoelastic and dielectric properties of composites of poly(vinyl butyral) and alumina particles with a high filling degree %U https://doi.org/10.1016/j.polymer.2015.11.047 %X Filler-filler and filler-matrix interactions in polymer composites increase with filler concentration and strongly influence the mechanical and rheological properties of polymer composites. By means of the spouted bed spray granulation process polymer composites with an extremely high concentration of inorganic fillers can be prepared. In this work, the viscoelastic properties of highly filled composites of poly(vinyl butyral) (PVB) and alumina particles are studied in the glassy, entanglement and terminal flow regime of poly(vinyl butyral). Ceramic-polymer composites with a volume concentration of inorganic particles between 61 vol% and 77 vol% were prepared. Such large filler fractions imply a strong effect of filler-filler interactions on the viscoelastic properties of the composite. Dynamic-mechanical thermal analysis reveals that the composites are characterized by a predominantly elastic behaviour below and above the glass transition temperature of the polymer phase because of strongly pronounced filler-filler and polymer-filler interactions. A phenomenological equation is proposed in order to describe the reinforcement effect which implies an increase of storage modulus by a factor of up to four orders of magnitude. The results of frequency and strain sweeps in the oscillatory mode show that the polymer phase strongly influences the deformation of the contact network of inorganic particles. Differential scanning calorimetry and broadband dielectric spectroscopy indicate that the glass transition temperature of poly(vinyl butyral) does not significantly differ within experimental resolution for pristine PVB and the PVB phase in the composites. %0 journal article %@ 0144-8617 %A Szopinski, D.,Handge, U.A.,Kulicke, W.-M.,Abetz, V.,Luinstra, G.A. %D 2016 %J Carbohydrate Polymers %N %P 834-840 %R doi:10.1016/j.carbpol.2015.09.067 %T Extensional Flow Behavior of Aqueous Guar Gum Derivative Solutions by Capillary Breakup Elongational Rheometry (CaBER) %U https://doi.org/10.1016/j.carbpol.2015.09.067 %X The extensional rheological properties of aqueous ionic carboxymethyl hydroxypropyl guar gum (CMHPG) and non-ionic hydroxypropyl guar gum (HPG) solutions between the semi-dilute solution state and the concentrated network solution state were investigated by capillary breakup elongational rheometry (CaBER). Carboxymethylated guar gum derivatives show an instable filament formation in deionized water. The ratio of elongational relaxation time λE over the shear relaxation time λS follows a power law ofλE/λS∼(c⋅[η])−2λE/λS∼c⋅η−2. The difference of the relaxation times in shear and elongation can be related to the loss of entanglements and superstructures in elongational flows at higher strains. %0 journal article %@ 0032-3861 %A Hiekkataipale, P.,Loebling, T.I.,Poutanen, M.,Priimagi, A.,Abetz, V.,Ikkala, O.,Groeschel, A.H. %D 2016 %J Polymer %N %P 456-465 %R doi:10.1016/j.polymer.2016.05.076 %T Controlling the shape of Janus nanostructures through supramolecular modification of ABC terpolymer bulk morphologies %U https://doi.org/10.1016/j.polymer.2016.05.076 %X Block copolymers microphase separate into a variety of bulk morphologies that serve as scaffolds, templates, masks and source for polymeric nano-particles. While supramolecular additives are common to complex within diblock copolymers to modify the morphology, the subtle effects of complexation on ABC triblock terpolymer morphologies are less explored. Here, we describe the manipulation of polystyrene-block-poly(4-vinylpyridine)-block-poly(tert-butyl methacrylate) (PS-b-P4VP-b-PT or S4VT) triblock terpolymer bulk morphologies through supramolecular complexation with rod-like 4-(4-pentylphenylazo)phenol (5PAP). The 5PAP molecule hydrogen bonds by phenolic groups to the 4VP repeating units and with increasing molar fraction of 5PAP, initially observed P4VP cylinders flatten into elliptic cylinders until a morphological transition occurs into a third (P4VP/5PAP) lamella. At sufficient 5PAP loadings, the cylinders can even merge into a perforated P4VP lamella located at the PS/PT interface. Quaternization of the P4VP phase and re-dispersion in organic solvent allows liberating S4VT Janus nanostructures from the bulk, including Janus cylinders, nanoporous Janus membranes and Janus sheets. The manipulation of “sandwiched” microphases through supramolecular binding motifs could allow the preparation of previously inaccessible terpolymer bulk morphologies and, in case of cross-linkable phases, lead to a larger library of Janus nano-objects. %0 journal article %@ 1022-1352 %A Georgopanos, P.,Filiz, V.,Handge, U.A.,Abetz, V. %D 2016 %J Macromolecular Chemistry and Physics %N 11 %P 1293-1304 %R doi:10.1002/macp.201500528 %T Chemical Modification, Thermal Characterization and Dielectric Spectroscopy of Polystyrene-block-Polyisoprene Diblock Copolymers %U https://doi.org/10.1002/macp.201500528 11 %X In this work, synthesis and chemical modification of a polystyrene-block-polyisoprene (PS-b-PI) diblock copolymer is presented. The modification reactions result in hydroxyl, amine, and carboxyl end-functional groups, respectively. Thermal analysis reveals a shift of the glass transition temperature of the polystyrene block to lower temperatures with respect to the polystyrene precursor because of the partial miscibility of the PS and the PI blocks. Comparing the glass transition temperature of the PS block of the three different end-functionalized diblock copolymers, the analysis in this work shows that a large end-group (i.e., the amine end-group) yields a lower glass transition temperature of the polystyrene block. The modified diblock copolymers were characterized by means of broadband dielectric spectroscopy in order to compare the results of thermal analysis and to monitor the dielectric relaxation behavior which is associated with the different end-functional groups. Comparing the dielectric loss of the pristine and the functionalized diblock copolymers, the segmental relaxation of the PS microphase is significantly influenced by the presence of these polar end-functional groups. %0 journal article %@ 0014-3057 %A Hoehme, C.,Hahn, J.,Lademann, B.,Meyer, A.,Bajer, B.,Abetz, C.,Filiz, V.,Abetz, V. %D 2016 %J European Polymer Journal %N %P 72-81 %R doi:10.1016/j.eurpolymj.2016.10.014 %T Formation of High Thermally Stable Isoporous Integral Asymmetric Block Copolymer Membranes %U https://doi.org/10.1016/j.eurpolymj.2016.10.014 %X Tailor-made poly(α-methylstyrene)- and poly(4-methylstyrene)-block-poly(4-vinylpyridine) diblock copolymers with poly(4-vinylpyridine) as the minority component were synthesised via living anionic polymerisation. In bulk they show spherical or cylindrical microphases. From these block copolymers highly-ordered isoporous block copolymer membranes were prepared by combining block copolymer selfassembly and the nonsolvent induced phase separation process (SNIPS). The membrane properties were analysed by water flux and retention measurements. Due to the high glass transition temperatures of the major blocks these block copolymer membranes show a thermal stability up to 150 °C. %0 journal article %@ 1750-5836 %A Pohlmann, J.,Bram, M.,Wilkner, K.,Brinkmann, T. %D 2016 %J International Journal of Greenhouse Gas Control %N %P 56-64 %R doi:10.1016/j.ijggc.2016.07.033 %T Pilot scale separation of CO2 from power plant flue gases by membrane technology %U https://doi.org/10.1016/j.ijggc.2016.07.033 %X Removing carbon dioxide from power plant flue gases is an increasingly important separation task to limit the amount of greenhouse gases emitted to the atmosphere. In contrast to competing processes, membrane technology requires less time to react to changing feed conditions. Hence it is ideally suited to operate efficiently even under partial load and at irregular intervals. I.e. the scenarios conventional power plants are facing today due to the increasing amount of renewable energy supplied to the power grid.,In this work the results of several experiments using a membrane gas separation pilot plant connected to a hard coal fired power plant are presented. Feed flowrate, temperature, dew point and composition as well as permeate pressure were varied during the experiments. The influences of these parameters on module performance, as well as the transition between different operating conditions were investigated. During these experiments the plant was frequently operated with ambient air during downtimes of the power plant. This allowed for a start-up and shut-down procedure to be developed, which is important to ensure the stability of the membrane. In order to gauge the stability of the process the experimental data is compared to a previously validated model. %0 journal article %@ 2468-0257 %A Olivieri, L.,Tena, A.,de Angelis, M.G.,Hernandez Gimenez, A.,Lozano, A.E.,Sarti, G.C. %D 2016 %J Green Energy and Environment %N 3 %P 201-210 %R doi:10.1016/j.gee.2016.09.002 %T The effect of humidity on the CO2/N2 separation performance of copolymers based on hard polyimide segments and soft polyether chains: Experimental and modeling %U https://doi.org/10.1016/j.gee.2016.09.002 3 %X In this work, we studied two copolymers formed by segments of a rubbery polyether (PPO or PEO) and of a glassy polyimide (BPDA-ODA or BKDA-ODA) suitable for gas separation and CO2 capture. Firstly, we assessed the absorption of water vapor in the materials, as a function of relative humidity (R.H.), finding that the humidity uptake of the copolymers lies between that of the corresponding pure homopolymers values. Furthermore, we studied the effect of humidity on CO2 and N2 permeability, as well as on CO2/N2 selectivity, up to R.H. of 75%. The permeability decreases with increasing humidity, while the ideal selectivity remains approximately constant in the entire range of water activity investigated. The humidity-induced decrease of permeability in the copolymers is much smaller than the one observed in polyimides such as Matrimid® confirming the positive effect of the polyether phase on the membrane performance.,Finally, we modeled the humidity-induced decrease of gas solubility, diffusivity and, consequently, permeability, using a suitable approach that considers the free volume theory for diffusion and LF model for solubility. Such model allows estimating the extent of competition that the gases undergo with water during sorption in the membranes, as a function of the relative humidity, as well as the expected reduction of free volume by means of water molecules occupation and consequent reduction of diffusivity. %0 journal article %@ 1022-1352 %A Gacal, B.N.,Filiz, V.,Abetz, V. %D 2016 %J Macromolecular Chemistry and Physics %N 5 %P 672-682 %R doi:10.1002/macp.201500381 %T The Synthesis of Poly(ethylene glycol) (PEG) Containing Polymers via Step-Growth Click Coupling Reaction for CO2 Separation %U https://doi.org/10.1002/macp.201500381 5 %X The synthesis of step-growth polymers via a step-growth click coupling reaction of diazides based on poly(ethylene glycol) (PEG) and dialkynes based on aromatics is reported. The polymers are characterized by proton nuclear magnetic resonance spectroscopy (1H-NMR), carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR), Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Gas transport properties of one polymer are measured by the time lag (constant volume, variable pressure) method. Low gas permeabilities are a consequence of the rather high glass transition temperature. The rather high selectivities in separation of CO2/N2 and CO2/CH4 result from the CO2-philic groups such as PEG, triazole, and benzoxazine. According to the gas permeation measurements, the membrane is stable in the temperature range from 30 to 90 °C. %0 journal article %@ 0009-286X %A Lillepaerg, J.,Pohlmann, J.,Rahman, M.,Brinkmann, T.,Shishatskiy, S.,Wind, J. %D 2016 %J Chemie - Ingenieur - Technik %N 9 %P 1273 %R doi:10.1002/cite.201650212 %T Membranmaterialentwicklung fuer CO2- Abtrennungsverfahren %U https://doi.org/10.1002/cite.201650212 9 %X No abstract %0 journal article %@ 0887-6266 %A Ntaras, C.,Polymeropoulos, G.,Zapsas, G.,Ntetsikas, K.,Liontos, G.,Karanastasis, A.,Moschovas, D.,Rangou, S.,Stewart-Sloan, C.,Hadjichristidis, E.L.T.,Avgeropoulos, A. %D 2016 %J Journal of Polymer Science B %N 15 %P 1443-1449 %R doi:10.1002/polb.24058 %T Synthesis, characterization and self-assembly of well-defined linear heptablock quaterpolymers %U https://doi.org/10.1002/polb.24058 15 %X Two well-defined heptablock quaterpolymers of the ABCDCBA type [Α: polystyrene (PS), B: poly(butadiene) with ∼90% 1,4-microstructure (PB1,4), C: poly(isoprene) with ∼55% 3,4-microstructure (PI3,4) and D: poly(dimethylsiloxane) (PDMS)] were synthesized by combining anionic polymerization high vacuum techniques and hydrosilylation/chlorosilane chemistry. All intermediates and final products were characterized by size exclusion chromatography, membrane osmometry, and proton nuclear magnetic resonance spectroscopy. Fourier transform infrared spectroscopy was used to further verify the chemical modification reaction of the difunctional PDMS. The self-assembly in bulk of these novel heptablock quarterpolymers, studied by transmission electron microscopy and small angle X-ray scattering, revealed 3-phase 4-layer alternating lamellae morphology of PS, PB1,4, and mixed PI3,4/PDMS domains. Differential scanning calorimetry was used to further confirm the miscibility of PI3,4 and PDMS blocks. It is the first time that PDMS is the central segment in such multiblock polymers (≥3 chemically different blocks). %0 journal article %@ 0376-7388 %A Olivieri, L.,Tena, A.,de Angelis, M.G.,Hernandez Gimenez, A.,Lozano, A.E.,Sarti, G.C. %D 2016 %J Journal of Membrane Science %N %P 187-200 %R doi:10.1016/j.memsci.2016.07.057 %T Sorption and transport of CO2 in copolymers containing soft (PEO, PPO) and hard (BKDA-ODA and BPDA-ODA) segments at different temperatures: Experimental data and modeling %U https://doi.org/10.1016/j.memsci.2016.07.057 %X In this work, we studied CO2 sorption and transport in two series of aliphatic-aromatic copolyimide membranes, as a function of chemical formulation, pressure and temperature. Such materials are formed by two distinct phases with rather different properties: the first one is formed of rubbery polyether segments (poly(propylene oxide) (PPO) or poly(ethylene oxide) (PEO)), characterized by favorable energetic interactions with CO2 and high flexibility, which endows the copolymers with high CO2 permeability, suitable for capture processes. The second phase is formed by hard glassy polyimide blocks, randomly distributed at the microscopic level, which provide the necessary thermal, chemical and mechanical stability.,Previous studies indicate that CO2 permeability increases with increasing the amount of polyether phase in the copolymers; in the present work we investigate more deeply the interactions and synergies occurring between the two phases, by focusing separately on the CO2 solubility and diffusivity terms that contribute to permeability.,In particular, by studying the shape of the solubility isotherm, as well as the values of diffusivity, sorption enthalpy and activation energy, we were able to monitor the transition from a glassy-like to a rubbery-like behavior as the fraction of rubbery component in the copolymer increases. The data indicate that polyether enhances CO2 permeability by acting mostly on diffusivity, while the solubility contribution is less affected on a quantitative basis. However, the qualitative behavior of solubility allows understanding the nature of interactions between the two phases. In particular, by using a simple additive approach to estimate the CO2 solubility of the copolymer, and the Non-Equilibrium Lattice Fluid (NELF) to evaluate the CO2 solubility in the pure homopolymers, one concludes that the copolymers sorption behavior is “ideal”, i.e. purely additive, indicating a good combination of the two phases. The copolymer volume, on the other hand, shows a contraction upon combination of the two phases. The NELF modeling of solubility data allows attributing such a contraction only to the glassy phase, whose excess free volume is reduced in the presence of the rubbery portion in the copolymer, which possibly partly occupies such excess volume, indicating a strong interpenetration of the two phases. %0 journal article %@ 0376-7388 %A Gruenauer, J.,Filiz, V.,Shishatskiy, S.,Abetz, C.,Abetz, V. %D 2016 %J Journal of Membrane Science %N %P 178-191 %R doi:10.1016/j.memsci.2016.07.005 %T Scalable application of thin film coating techniques for supported liquid membranes for gas separation made from ionic liquids %U https://doi.org/10.1016/j.memsci.2016.07.005 %X The application of commercial polyacrylonitrile (PAN) membranes as matrix material for ionic liquids (ILs) for gas separation tasks is reported and morphological characteristics for supported liquid membrane stability are discussed. The compatibility of membrane components was investigated and two thin film coating techniques, dip coating and spin coating, were compared. The dip coating technique has proven to fulfill the requirement of membrane stability, as well as pin-hole free coating and thin coating thickness. The thickness of the ionic liquid layer in the membrane could be assessed by means of a modified Landau-Levich approach. Overall liquid membranes supported by PAN with a narrow pore size distribution achieved remarkably good results especially in combination with 1-ethyl-3-methylimidazolium tetracyanoborate (EMIM TCB) ionic liquid and are showing the way to commercially scalable supported liquid membrane application. %0 journal article %@ 0024-9297 %A Lo, T.-Y.,Dehghan, A.,Georgopanos, P.,Avgeropoulos, A.,Shi, A.-C.,Ho, R.-M. %D 2016 %J Macromolecules %N 2 %P 624-633 %R doi:10.1021/acs.macromol.5b02685 %T Orienting Block Copolymer Thin Films via Entropy %U https://doi.org/10.1021/acs.macromol.5b02685 2 %X Controlling the orientation of nanostructured thin films of block copolymers (BCPs) is essential for next-generation lithography using BCPs. According to conventional wisdom, the orientation of BCP thin films is mainly determined by molecular interactions (enthalpy-driven orientation). Here, we show that the entropic effect can be used to control the orientation of BCP thin films. Specifically, we used the architecture of star-block copolymers consisting of polystyrene (PS) and poly(dimethylsiloxane) (PDMS) blocks to regulate the entropic contribution to the self-assembled nanostructures. The study unequivocally demonstrate that for star-block copolymers with the same volume fractions of PS and PDMS, perpendicularly oriented BCP nanostructures could be induced via an entropic effect regulated by the number of arms. Also, the feasibility of using the star-block copolymer thin films for practical applications is demonstrated by using the thin film as a mask for nanolithography or as a template for the fabrication of nanoporous monolith. %0 journal article %@ 2296-4185 %A Defterali, C.,Verdejo, R.,Majeed, S.,Boschetti de Fierro, A.,Mendez-Gomez, H.R.,Diaz-Guerra, E.,Fierro, D.,Buhr, K.,Abetz, C.,Martinez-Murillo, R.,Vuluga, D.,Alexandre, M.,Thomassin, J.-M.,Detrembleur, C.,Jerome, C.,Abetz, V.,Lopez-Manchado, M.A.,Vicario-Abejon, C. %D 2016 %J Frontiers in Bioengineering and Biotechnology %N %P 94 %R doi:10.3389/fbioe.2016.00094 %T In Vitro Evaluation of Biocompatibility of Uncoated Thermally Reduced Graphene and Carbon Nanotube-Loaded PVDF Membranes with Adult Neural Stem Cell-Derived Neurons and Glia %U https://doi.org/10.3389/fbioe.2016.00094 %X Graphene, graphene-based nanomaterials (GBNs), and carbon nanotubes (CNTs) are being investigated as potential substrates for the growth of neural cells. However, in most in vitro studies, the cells were seeded on these materials coated with various proteins implying that the observed effects on the cells could not solely be attributed to the GBN and CNT properties. Here, we studied the biocompatibility of uncoated thermally reduced graphene (TRG) and poly(vinylidene fluoride) (PVDF) membranes loaded with multi-walled CNTs (MWCNTs) using neural stem cells isolated from the adult mouse olfactory bulb (termed aOBSCs). When aOBSCs were induced to differentiate on coverslips treated with TRG or control materials (polyethyleneimine-PEI and polyornithine plus fibronectin-PLO/F) in a serum-free medium, neurons, astrocytes, and oligodendrocytes were generated in all conditions, indicating that TRG permits the multi-lineage differentiation of aOBSCs. However, the total number of cells was reduced on both PEI and TRG. In a serum-containing medium, aOBSC-derived neurons and oligodendrocytes grown on TRG were more numerous than in controls; the neurons developed synaptic boutons and oligodendrocytes were more branched. In contrast, neurons growing on PVDF membranes had reduced neurite branching, and on MWCNTs-loaded membranes oligodendrocytes were lower in numbers than in controls. Overall, these findings indicate that uncoated TRG may be biocompatible with the generation, differentiation, and maturation of aOBSC-derived neurons and glial cells, implying a potential use for TRG to study functional neuronal networks. %0 journal article %@ 0376-7388 %A Mueller, N.,Handge, U.A.,Abetz, V. %D 2016 %J Journal of Membrane Science %N %P 33-46 %R doi:10.1016/j.memsci.2016.05.055 %T Physical ageing and lifetime prediction of polymer membranes for gas separation processes %U https://doi.org/10.1016/j.memsci.2016.05.055 %X The free volume in glassy polymers for gas separation processes is affected decidedly by physical ageing. In this work, we analyse the long-term volume relaxation of glassy polymer membranes using statistical data analysis in order to predict the lifetime of these membranes with minimal experimental effort. Several lifetime definitions are proposed and discussed in their use for the prediction quality. A principal objective of this work is the statistical analysis of the phenomenological ageing model developed by Struik using the bootstrapping method. We analyse the stepwise reduction of the number of data points used in model fitting. Based on these results we propose an optimal modelling and experimental strategy directed at the prediction of thickness dependent volume relaxation. In particular, the influence of the duration of pointwise measurements is discussed in detail. Our investigation is concluded by the dimensional analysis of the Struik equation, resulting in a master curve concept. The analysis of the master curve reveals a weak dependence of the lifetime of a membrane on its initial condition. The lifetime is proportional to the relaxation time for a criterion based on the absolute permeability and inverse proportional to the relaxation time for a criterion based on the derivative of the permeability for the chosen threshold parameters. %0 journal article %@ 1022-1336 %A Abetz, V. %D 2015 %J Macromolecular Rapid Communications %N 1 %P 10-22 %R doi:10.1002/marc.201400556 %T Isoporous block copolymer membranes %U https://doi.org/10.1002/marc.201400556 1 %X The developments in membranes based on tailored block copolymers are reported with an emphasis on isoporous membranes. These membranes can be prepared in different geometries, namely flat sheets and hollow fibers. They display narrow pore size distributions due to their formation by self-assembly. The preparation of these membranes and possibilities to further functionalize such membranes will be discussed. Different ways to control the pore size will be addressed, and the potential of block copolymer blends to fabricate membranes with tailored pore sizes will be shown. %0 journal article %@ 0032-3861 %A Schulze, M.,Handge, U.A.,Rangou, S.,Lillepaerg, J.,Abetz, V. %D 2015 %J Polymer %N %P 88-99 %R doi:10.1016/j.polymer.2015.06.005 %T Thermal properties, rheology and foams of polystyrene-block-poly(4-vinylpyridine) diblock copolymers %U https://doi.org/10.1016/j.polymer.2015.06.005 %X In this study, the thermal and rheological properties of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers are investigated in order to get information about the optimum foaming temperature. Foams of these diblock copolymers were prepared using the technique of batch foaming with carbon dioxide as environmentally-benign blowing agent. The tailored PS-b-P4VP diblock copolymers with different molecular weights and a cylindrical morphology were prepared and analysed regarding their thermal stability. High-pressure differential scanning calorimetry exposes the plasticising effect of the blowing agent which yields a decrease of the glass transition temperature of the polystyrene and the poly(4-vinylpyridine) blocks. Sorption measurements were performed in order to measure the uptake of carbon dioxide in the diblock copolymer. Additionally, rheological experiments in the oscillatory mode were conducted which confirmed a microphase-separated structure of the PS-b-P4VP diblock copolymers by a plateau of the storage and loss moduli in the temperature range of processing. In shear and melt elongation, the transient shear viscosity and the transient elongational viscosity were much smaller than the linear viscoelastic prediction at later times. The analysis of the foam morphology revealed that the foam density of the diblock copolymers as measured via Archimedes' principle exhibits the lowest foam density at a molecular weight in the order of 160 kg mol−1. %0 journal article %@ 0935-9648 %A Radjabian, M.,Abetz, V. %D 2015 %J Advanced Materials %N 2 %P 352-355 %R doi:10.1002/adma.201404309 %T Tailored Pore Sizes in Integral Asymmetric Membranes Formed by Blends of Block Copolymers %U https://doi.org/10.1002/adma.201404309 2 %X A simple way to generate isoporous membranes with tailored pore sizes is shown. Block copolymers of different compositions are blended in solution and membranes are obtained by solution casting followed by nonsolvent-induced phase separation. This enables the preparation of integral asymmetric membranes with a defined pore size for given sets of block copolymers just by choosing the right blend composition. %0 journal article %@ 1381-5148 %A Rahman, M.M.,Filiz, V.,Khan, M.M.,Gacal, B.N.,Abetz, V. %D 2015 %J Reactive and Functional Polymers %N %P 125-133 %R doi:10.1016/j.reactfunctpolym.2014.07.006 %T Functionalization of POSS nanoparticles and fabrication of block copolymer nanocomposite membranes for CO2 separation %U https://doi.org/10.1016/j.reactfunctpolym.2014.07.006 %X Synthesis of methoxy poly(ethylene glycol) (PEG) functionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticles via epoxy ring opening reaction in three different solvents are outlined in this manuscript. The nanoparticles are used as filler for commercial poly(ether-block-amide) multiblock copolymer PEBAX® MH 1657. The influence of two novel structural features of the synthesized nanofillers on the gas separation performance of nanocomposite membranes are studied on the examples of CO2/N2 and CO2/H2 gas pairs. These are – (i) presence of a dimethylsilyl group as spacer between the cage structure of POSS and the PEG ligand and (ii) formation of a tetrahydrofuran (THF) complex. While ideal selectivity characteristics for the matrix polymer are not significantly affected by the presence of fillers, the single gas permeability (determined by time-lag method) is remarkably increased in both cases. %0 journal article %@ 2046-2069 %A Tena, A.,Shishatskiy, S.,Filiz, V. %D 2015 %J RSC Advances %N 29 %P 22310-22318 %R doi:10.1039/C5RA01328C %T Poly(ether–amide) vs. poly(ether–imide) copolymers for post-combustion membrane separation processes %U https://doi.org/10.1039/C5RA01328C 29 %X This work is focused on the comparison between the commercial polyamide PEBAX® MH 1657 and a new set of synthetized polyimides with different polyethylene glycol lengths. The samples were synthesized with the same poly(ethylene oxide) (PEO) content (57 wt%) for comparison with the commercial polymer. All polymers have been characterized by several techniques revealing a direct relationship between crystallinity, PEO length and permeability properties. Results at temperatures lower than the Tm of the polyether blocks confirm that lower PEO crystallinity corresponds to higher permeability. At temperatures higher than the Tm of the PEO block, no significant differences were found between the commercial polyamides and the synthesized polyimides. This confirms that the aliphatic phase controls the separation while the hard block provides mechanical strength. Remarkable are the results for the CO2/N2 separation. These new copolyimides are promising materials for post-combustion processes. %0 journal article %@ 1944-8244 %A Rahman, M.M.,Filiz, V.,Shishatskiy, S.,Abetz, C.,Georgopanos, P.,Khan, M.M.,Neumann, S.,Abetz, V. %D 2015 %J ACS Applied Materials and Interfaces %N 23 %P 12289-12298 %R doi:10.1021/am504223f %T Influence of Poly(ethylene glycol) Segment Length on CO2 Permeation and Stability of PolyActive Membranes and Their Nanocomposites with PEG POSS %U https://doi.org/10.1021/am504223f 23 %X Three grades of PolyActive block copolymers are investigated for CO2 separation from light gases. The polymers are composed of 23 wt % poly(butylene terephthalate) (PBT) and 77 wt % poly(ethylene glycol terephthalate) (PEGT) having the poly(ethylene glycol) segments of 1500, 3000, and 4000 g/mol, respectively. A commercial PEG POSS (poly(ethylene glycol) functionalized polyoctahedral oligomeric silsesquioxanes) is used as a nanofiller for these polymers to prepare nanocomposites via a solvent casting method. Single gas permeabilities of N2, H2, CH4, and CO2 are measured via the time-lag method in the temperature range from 30 to 70 °C. The thermal transitions of the prepared membranes are studied by differential scanning calorimetry (DSC). It is found that the length of PEG segment has a pronounced influence on the thermal transition of the polymers that regulates the gas separation performance of the membranes. The stability of the nanocomposites is also correlated with the thermal transition of the polyether blocks of the polymer matrices. %0 journal article %@ 0887-6266 %A Koschine, T.,Raetzke, K.,Faupel, F.,Khan, M.M.,Emmler, T.,Filiz, V.,Abetz, V.,Ravelli, L.,Egger, W. %D 2015 %J Journal of Polymer Science B %N 3 %P 213-217 %R doi:10.1002/polb.23616 %T Correlation of gas permeation and free volume in new and used high free volume thin film composite membranes %U https://doi.org/10.1002/polb.23616 3 %X Polymeric gas separation membranes frequently undergo the phenomenon of aging, that is, performance parameters like permeability decrease with storage or usage time. Here, we report on a new approach of reducing aging by incorporation of functionalized multiwalled carbon nanotubes into a polymer of intrinsic microporosity. Free volume and permeability measurements clearly show a reduced aging with incorporation of the carbon nantubes. %0 journal article %@ 0376-7388 %A Brinkmann, T.,Naderipour, C.,Pohlmann, J.,Wind, J.,Wolff, T.,Esche, E.,Mueller, D.,Wozny, G.,Hoting, B. %D 2015 %J Journal of Membrane Science %N %P 237-247 %R doi:10.1016/j.memsci.2015.03.082 %T Pilot Scale Investigatons of the Removal of Carbon Dioxide from Hydrocarbon Gas Streams Using Polyethylene – Polybutyleneteraphtalate (POLYACTIVE®) Thin Film Composite Membranes %U https://doi.org/10.1016/j.memsci.2015.03.082 %X The focus of this contribution is the separation of carbon dioxide from biogas and hydrocarbon containing gaseous reaction products using a high flux flat sheet membrane. The thin selective layer of the membranes is made from the commercial blockcopolymer Polyactive®. The membrane material is manufactured reproducibly on a technical scale and installed into membrane modules. The modules were investigated in three pilot plants: two for the removal of carbon dioxide from methane and one for the separation of carbon dioxide from gaseous hydrocarbon streams. The pilot plant experiments confirmed a rapid approach to steady state operation and the dependence of the separation result on the employed pressure ratio. For the biogas applications it was shown that a single stage process is sufficient to achieve methane purities in excess of 95 mol-% in the retentate at methane recoveries of 70%, as well as carbon dioxide mole fractions larger than 60 mol-% in the permeate. Carbon dioxide could also be removed successfully from gaseous, hydrocarbon containing product streams employing the investigated high flux membranes. The employed simulation model for the modules predicted the experimental results well and proofed to be a valuable tool. %0 journal article %@ 2152-3878 %A Wolff, T.,Brinkmann, T.,Kerner, M.,Hindersin, S. %D 2015 %J Greenhouse Gases: Science and Technology %N 5 %P 505-512 %R doi:10.1002/ghg.1510 %T CO2 enrichment from flue gas for the cultivation of algae – A field test %U https://doi.org/10.1002/ghg.1510 5 %X A membrane unit in pilot scale is operated to provide a CO2-enriched product stream from flue gas of a natural-gas-fuelled heating system. The CO2 stream is fed to a cultivation medium of photobioreactors that are integrated in the façade of the building project ‘BIQ – The Algae House’ (International Building Exhibition 2013/Hamburg), where CO2 is required as the carbon source for the growth of algae, which are cultivated in the bioreactors. This work presents a long-term field test. Furthermore, a possibility for the usage of CO2 separated de-centrally is given. The operational conditions for the membrane module cause additional mechanical stress on the membrane material since the pilot plant is operated with periodic start-ups and shut-downs. The occurrence of acidic water on the membrane generates additional potential damage of the material. The field test is planned to be carried out for several years to prove the reliability of this membrane technology in flue gas treatment. %0 journal article %@ 2077-0375 %A Khan, M.M.,Filiz, V.,Emmler, T.,Abetz, V.,Koschine, T.,Raetzke, K.,Faupel, F.,Egger, W.,Ravelli, L. %D 2015 %J Membranes %N 2 %P 214-227 %R doi:10.3390/membranes5020214 %T Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity %U https://doi.org/10.3390/membranes5020214 2 %X High free-volume copolymers were prepared via polycondensation with 2,3,5,6,-tetrafluoroterephthalonitrile (TFTPN) in which a portion of the 3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI) of PIM-1 was replaced with dibutyl anthracene maleimide (4bIII). An investigation of free volume using positron annihilation lifetime spectroscopy (PALS), and gas permeation measurements was carried out for the thin film composite copolymer membranes and compared to PIM-1. The average free volume hole size and the gas permeance of the copolymer membranes increased with decreasing TTSBI content in the copolymer. %0 journal article %@ 1944-8244 %A Hahn, J.,Clodt, J.I.,Abetz, C.,Filiz, V.,Abetz, V. %D 2015 %J ACS Applied Materials and Interfaces %N 38 %P 21130-21137 %R doi:10.1021/acsami.5b04658 %T Thin Isoporous Block Copolymer Membranes: It Is All about the Process %U https://doi.org/10.1021/acsami.5b04658 38 %X The combination of the self-assembly of amphiphilic block copolymers and the nonsolvent induced phase inversion process offers an efficient way to isoporous integral-asymmetric membranes. In this context we report fast, easily upscalable and material reducing ways to thin self-assembled membranes. Therefore, we succeeded to implement a spray or dip coating step into the membrane formation process of different diblock copolymers like polystyrene-block-poly(4-vinylpyridine), poly(α-methylstyrene)-bock-poly(4-vinylpyridine), and polystyrene-block-poly(iso-propylglycidyl methacrylate). The formation of hexagonal pore structures was possible using a highly diluted one solvent system allowing the reduction of diblock copolymer consumption and therefore the production costs are minimized compared to conventional blade casting approaches. The broad applicability of the process was proven by using different flat and hollow fiber support materials. Furthermore, the membranes made by this new method showed a more than 6-fold increase in water flux compared to conventional polystyrene-block-poly(4-vinylpyridine) membranes with similar pore sizes prepared by blade casting. The membranes could be proven to be stable at transmembrane pressures of 2 bar and showed a pH responsive flux behavior over several cycles. %0 journal article %@ 0024-9297 %A Stegelmeier, C.,Exner, A.,Hauschild, S.,Filiz, V.,Perlich, J.,Roth, S.V.,Abetz, V.,Foerster, S. %D 2015 %J Macromolecules %N 5 %P 1524-1530 %R doi:10.1021/ma502375h %T Evaporation-Induced Block Copolymer Self-Assembly into Membranes Studied by in Situ Synchrotron SAXS %U https://doi.org/10.1021/ma502375h 5 %X Amphiphilic diblock copolymers can spontaneously form integral asymmetric isoporous membranes by evaporation-induced self-assembly. The critical structural evolution steps occur within the first hundred seconds after solvent casting. By using synchrotron X-ray scattering employing a specially designed solvent casting apparatus, we were able to follow the kinetics of the structural evolution in situ. At an initial time of 20 s after solvent-casting we observe the first structural features on length scales d of 30–70 nm, signaled by a weak maximum in the low-q region of the measured scattering curves. During the subsequent period the length scales increase continuously until after around 100 s they reach a plateau value d∞ of 80–120 nm, the size depending on the molecular weight of the block copolymer. Interestingly, the time evolution of the characteristic length scales follow a simple exponential saturation curve for all block copolymers, irrespective of molecular weight, composition, and addition of ionic additives, in agreement with theoretical models on two-dimensional ordered block copolymer domain formation. In addition, we could show that immersion in water during solvent evaporation leads to a nearly instantaneous increase of the characteristic length scale to its plateau value. The addition of salts such as Cu2+ leads to compaction of the structures with smaller characteristic length scales, but still following the same kinetic evolution. %0 journal article %@ 0887-6266 %A Zapsas, G.,Moschovas, D.,Ntetsikas, K.,Rangou, S.,Lee, J.-H.,Thomas, E.L.,Zafeiropoulos, N.E.,Avgeropoulos, A. %D 2015 %J Journal of Polymer Science B %N 17 %P 1238-1246 %R doi:10.1002/polb.23759 %T Immiscible polydiene blocks in linear copolymer and terpolymer sequences %U https://doi.org/10.1002/polb.23759 17 %X Synthesis, molecular, and morphological characterization of two linear diblock copolymers consisting of two polydienes with specific geometric isomerisms and two triblock terpolymers with a combination of the same polydienes with polystyrene are investigated for both lower and very high molecular weights. This work is inspired from a previous research study which demonstrated that linear ABC terpolymers consisting of polystyrene, poly(butadiene), and poly(isoprene), with specific geometric isomerisms for the polydienes, lead to 3-phase microphase separated systems. We report also the coexistence of the core-shell double gyroid and the 3-phase 4-layer alternating lamellae morphologies with the majority fraction being the lamellar structure. %0 journal article %@ 0040-4020 %A He, L.-Y.,Urrego-Riveros, S.,Gates, P.J.,Naether, C.,Brinkmann, M.,Abetz, V.,Staubitz, A. %D 2015 %J Tetrahedron %N 33 %P 5399-5406 %R doi:10.1016/j.tet.2015.05.091 %T Synthesis of poly(thiophene-alt-pyrrole) from a difunctionalized thienylpyrrole by Kumada polycondensation %U https://doi.org/10.1016/j.tet.2015.05.091 33 %X A difunctional thienylpyrrole monomer with a bromide on the thienyl moiety and a magnesium halide on the pyrrole moiety was prepared via chemo-selective magnesium–iodine exchange. Based on this monomer, a π-conjugated alternating poly(thiophene-alt-pyrrole) PTP was synthesized via nickel and palladium catalyzed Kumada polycondensation. The optical and thermal properties of this polymer have been investigated and suggested a wide band gap polymer, with a very low Tg for such polymers. %0 journal article %@ 0376-7388 %A Clodt, J.I.,Bajer, B.,Buhr, K.,Hahn, J.,Filiz, V.,Abetz, V. %D 2015 %J Journal of Membrane Science %N %P 334-340 %R doi:10.1016/j.memsci.2015.07.041 %T Performance study of isoporous membranes with tailored pore sizes %U https://doi.org/10.1016/j.memsci.2015.07.041 %X This performance study deals with isoporous ultrafiltration membranes made through a combination of self-assembly of amphiphilic block copolymers and the non-solvent induced phase separation process (SNIPS). Ten different polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers were used to prepare membranes with pore sizes increasing with the molecular weight of the polymers. The pore diameters of the membranes vary from 17 to 86 nm. Pure water permeances were studied with respect to pore sizes, P4VP content, thickness of the membranes and flux recovery after protein adsorption. Suitable working conditions were identified and rejection of poly(ethylene glycol) (PEG) molecules with molecular weights between 100 and 1000 kDa were carried out. The characteristics of PS-b-P4VP diblock copolymer membranes were compared with a commercially available polyethersulfone ultrafiltration membrane. %0 journal article %@ 0376-7388 %A Khan, M.M.,Filiz, V.,Bengtson, G.,Shishatskiy, S.,Rahman, M.M.,Lillepaerg, J.,Abetz, V. %D 2015 %J Journal of Membrane Science %N %P 610-611 %R doi:10.1016/j.memsci.2015.01.002 %T Corrigendum to: “Enhanced gas permeability by fabricating mixed matrix membranes of functionalized multiwalled carbon nanotubes and polymers of intrinsic microporosity (PIM)” published in J. Membr. Sci. 436 (2013) 109–120 %U https://doi.org/10.1016/j.memsci.2015.01.002 %X No abstract %0 journal article %@ 1438-7492 %A Otto, C.,Handge, U.A.,Aschenbrenner, O.,Kerwitz, J.,Abetz, C.,Abetz, V. %D 2015 %J Macromolecular Materials and Engineering %N 12 %P 1246-1256 %R doi:10.1002/mame.201500088 %T Solvent-Free Preparation of Electrically Conductive Polyetherimide Membranes Using Carbon Nanotubes %U https://doi.org/10.1002/mame.201500088 12 %X A chemical-free option to reduce membrane fouling is the use of electrical fields for membranes. To maximize the strength of the electric field in compact membrane module constructions, electrically conductive membranes are preferred to only conductive supports. Conductive, porous membranes are sintered from polyetherimide powder particles that are surface-covered with multi-walled carbon nanotubes (MWCNT). The fusion of the surface-covered particles forms a conductive MWCNT network in the composite, with a large number of inter-MWCNT contacts. Membranes with a high specific electrical conductivity of up to 2.28 Sm−1 at a concentration of 3.0 wt% MWCNT are produced in an adapted sintering process. The sintering behavior of decorated particles depends on the coverage of the polymer particles. %0 journal article %@ 1750-5836 %A Brinkmann, T.,Pohlmann, J.,Bram, M.,Zhao, L.,Tota, A.,Escalona, N.J.,de Graaff, M.,Stolten, D. %D 2015 %J International Journal of Greenhouse Gas Control %N %P 194-204 %R doi:10.1016/j.ijggc.2015.03.010 %T Investigating the influence of the pressure distribution in a membrane module on the cascaded membrane system for post-combustion capture %U https://doi.org/10.1016/j.ijggc.2015.03.010 %X Polyactive® membranes show promising properties for CO2 separation from flue gas. An investigation of different module types using Polyactive® membranes was carried out for this paper. A test rig was built to explore, amongst other process parameters, the pressure drop in envelope-type membrane modules. The experimental data and simulation results were compared with quite good consistency. This validation enabled further simulations for different modules in a virtual pilot plant configuration. Applying the data from the pilot plant simulation to a reference power plant, the scaled-up cascaded membrane system was analyzed using different membrane modules. Considering the required membrane area, energy consumption and pressure drop in different modules, a counter-current membrane module configuration exhibited the best performance and had a marginal advantage in comparison with the chemical absorption process. %0 journal article %@ 0376-7388 %A Gruenauer, J.,Shishatskiy, S.,Abetz, C.,Abetz, V.,Filiz, V. %D 2015 %J Journal of Membrane Science %N %P 224-233 %R doi:10.1016/j.memsci.2015.07.054 %T Ionic liquids supported by isoporous membranes for CO2/N2 gas separation applications %U https://doi.org/10.1016/j.memsci.2015.07.054 %X The usage of isoporous polystyrene-block-poly(4-vinylpyridine) diblock copolymer (PS-b-P4VP) membranes as matrix material for ionic liquids (ILs) for gas separation tasks is reported and compared to an anodic alumina membrane. The compatibility of membrane components was investigated by means of porometry, tensiometry and contact angle measurement. The CO2 gas diffusivity and solubility was determined by direct observation using a “time-lag” facility and a magnetic suspension balance. Overall liquid membranes supported by PS-b-P4VP achieved remarkably good results especially in combination with 1-ethyl-3-methylimidazolium dicyanoamide (EMIM DCA) ionic liquid and are showing the way to attractive research and application opportunities. %0 journal article %@ 0897-4756 %A Lindemann, P.,Tsotsalas, M.,Shishatskiy, S.,Abetz, V.,Krolla-Sidenstein, P.,Azucena, C.,Monnereau, L.,Beyer, A.,Goelzhaeuser, A.,Mugnaini, V.,Gliemann, H.,Braese, S.,Woell, C. %D 2014 %J Chemistry of Materials %N 24 %P 7189-7193 %R doi:10.1021/cm503924h %T Preparation of Freestanding Conjugated Microporous Polymer Nanomembranes for Gas Separation %U https://doi.org/10.1021/cm503924h 24 %X Conjugated microporous polymers (CMPs) have attracted much interest due to their intrinsic porosity, outstanding stability, and high variability. However, the processing of these materials for membrane application has been limited due to their insoluble nature when synthesized as bulk material. Here we report the synthesis of freestanding CMP-nanomembranes via layer-by-layer growth of a “click” based conjugated microporous polymer on a sacrificial substrate. After dissolution of the substrate the CMP-nanomembrane can be transferred to porous substrates and continuously cover holes of up to 50 μm diameter. The CMP-nanomembranes appear defect-free as inferred from high selectivity values obtained from gas permeation experiments and from electrochemical investigation in the presence of ferrocene. The presented synthesis method represents a versatile strategy to incorporate CMP materials in functional devices for membrane separation, catalysis, or organic electronics. %0 journal article %@ 2046-2069 %A Hahn, J.,Clodt, J.I.,Filiz, V.,Abetz, V. %D 2014 %J RSC Advances %N 20 %P 10252-10260 %R doi:10.1039/C3RA47306F %T Protein separation performance of self-assembled block copolymer membranes %U https://doi.org/10.1039/C3RA47306F 20 %X A comprehensive study of the separation performance of highly porous self-assembled integral asymmetric block copolymer membranes was carried out. Four different polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers were used to prepare membranes with pore sizes increasing with the molecular weight of the polymers. The pore sizes vary from 17 nm to 53 nm. Clean water fluxes and the adsorption of lysozyme, myoglobin, haemoglobin, catalase and ferritin on the membranes were studied. Diffusion rates of the proteins were examined and selectivities are discussed. The membranes show promising results regarding the separation of different proteins in the range of around four to twelve nm. The characteristics of PS-b-P4VP diblock copolymer membranes were compared with a commercially available polycarbonate track-etched membrane. %0 journal article %@ 0935-9648 %A Ai, M.,Shishatskiy, S.,Wind, J.,Zang, X.,Nottbohm, C.T.,Mellech, N.,Winter, A.,Vieker, H.,Qiu, J.,Dietz, K.-J.,Goelzhaeuser, A.,Beyer, A. %D 2014 %J Advanced Materials %N 21 %P 3421-3426 %R doi:10.1002/adma.201304536 %T Carbon Nanomembranes (CNMs) Supported by Polymer: Mechanics and Gas Permeation %U https://doi.org/10.1002/adma.201304536 21 %X Gas permeation characteristics of carbon nanomembranes (CNMs) from self-assembled monolayers are reported for the first time. The assembly of CNMs onto polydimethylsiloxane (PDMS) support membranes allows mechanical measurements under compression as well as determination of gas permeation characteristics. The results suggest that molecular-sized channels in CNMs dominate the permeation properties of the 1 nm thin CNMs. %0 journal article %@ 1996-1944 %A Homaeigohar, S.,Elbahri, M. %D 2014 %J Materials %N 2 %P 1017-1045 %R doi:10.3390/ma7021017 %T Nanocomposite Electrospun Nanofiber Membranes for Environmental Remediation %U https://doi.org/10.3390/ma7021017 2 %X Rapid worldwide industrialization and population growth is going to lead to an extensive environmental pollution. Therefore, so many people are currently suffering from the water shortage induced by the respective pollution, as well as poor air quality and a huge fund is wasted in the world each year due to the relevant problems. Environmental remediation necessitates implementation of novel materials and technologies, which are cost and energy efficient. Nanomaterials, with their unique chemical and physical properties, are an optimum solution. Accordingly, there is a strong motivation in seeking nano-based approaches for alleviation of environmental problems in an energy efficient, thereby, inexpensive manner. Thanks to a high porosity and surface area presenting an extraordinary permeability (thereby an energy efficiency) and selectivity, respectively, nanofibrous membranes are a desirable candidate. Their functionality and applicability is even promoted when adopting a nanocomposite strategy. In this case, specific nanofillers, such as metal oxides, carbon nanotubes, precious metals, and smart biological agents, are incorporated either during electrospinning or in the post-processing. Moreover, to meet operational requirements, e.g., to enhance mechanical stability, decrease of pressure drop, etc., nanofibrous membranes are backed by a microfibrous non-woven forming a hybrid membrane. The novel generation of nanocomposite/hybrid nanofibrous membranes can perform extraordinarily well in environmental remediation and control. This reality justifies authoring of this review paper. %0 conference lecture %@ %A Homaeigohar, S.,Koll, J.,Elbahri, M. %D 2014 %J 10th International Congress on Membranes and Membrane Processes, ICOM 2014 %N %P %T Chopped graphite nanofibrous membranes for water treatment %U %X %0 journal article %@ 0032-3861 %A Radjabian, M.,Koll, J.,Buhr, K.,Vainio, U.,Abetz, C.,Handge, U.A.,Abetz, V. %D 2014 %J Polymer %N 13 %P 2986-2997 %R doi:10.1016/j.polymer.2014.04.041 %T Tailoring the Morphology of Self-Assembled Block Copolymer Hollow Fiber Membranes %U https://doi.org/10.1016/j.polymer.2014.04.041 13 %X Isoporous asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) hollow fiber membranes were successfully made by a dry-jet wet spinning process. Well-defined nanometer-scale pores around 20-40 nm in diameter were tailored on the top surface of the fiber above a non-ordered macroporous layer by combining block copolymer self-assembly and non-solvent induced phase separation (SNIPS). Uniformity of the surface-assembled pores and fiber cross-section morphology was improved by adjusting the solution concentration, solvent composition as well as some important spinning parameters such as bore fluid flow rate, polymer solution flow rate and air gap distance between the spinneret and the precipitation bath. The formation of the well-organized self-assembled pores is a result of the interplay of fast relaxation of the shear-induced oriented block copolymer chains, the rapid evaporation of the solvent mixture on the outer surface and solvent extraction into the bore liquid on the lumen side, and gravity force during spinning. Structural features of the block copolymer solutions were investigated by small angle X-ray scattering (SAXS) and rheological properties of the solutions were examined as well. The scattering patterns of the optimal solutions for membrane formation indicate a disordered phase which is very close to the disorder-order transition. The nanostructured surface and cross-section morphology of the membranes were characterized by scanning electronic microscopy (SEM). The water flux of the membranes was measured and gas permeation was examined to test the pressure stability of the hollow fibers. %0 journal article %@ 0303-402X %A Georgopanos, P.,Rangou, S.,Haenelt, T.G.,Abetz, C.,Meyer, A.,Filiz, V.,Handge, U.A.,Abetz, V. %D 2014 %J Colloid and Polymer Science %N 8 %P 1877-1891 %R doi:10.1007/s00396-014-3284-y %T Analysis of glass transition and relaxation processes of low molecular weight polystyrene-Beta-polyisoprene diblock copolymers %U https://doi.org/10.1007/s00396-014-3284-y 8 %X The objective of this study is to analyze the glass transition temperature and relaxation processes of low molecular weight polystyrene-block-polyisoprene diblock copolymers with different compositions, synthesized via anionic polymerization. Thermal properties were investigated by differential scanning calorimetry and dynamic-mechanical thermal analysis, while the morphologies at room temperature were investigated by transmission electron microscopy and small-angle X-ray scattering. The χN values indicate that the diblock copolymers lie near the weak segregation regime. Three different experimental techniques were applied to determine the dynamic properties, i.e., linear viscoelastic shear oscillations, creep recovery experiments, and dielectric spectroscopy. The rheological experiments were performed above the order–disorder transition temperature where the diblock copolymers behave like a Maxwell fluid. Our results indicate that the presence of the polyisoprene segments strongly influences the monomeric friction coefficient and the tendency to form entanglements above the order–disorder temperature. Consequently, the zero-shear rate viscosity of a diblock copolymer is much lower than the zero-shear rate viscosity of the neat polystyrene block (the polystyrene precursor of the polymerization procedure). Dielectric spectroscopy enables the analysis of relaxation processes below the glass transition of the polystyrene microphase. Frequency sweeps indicate the dynamic glass transition of the polyisoprene blocks, which are partly mixed with the polystyrene blocks, which are always the majority component in the block copolymers of this study. %0 journal article %@ 0743-7463 %A Keskin, D.,Clodt, J.I.,Hahn, J.,Abetz, V.,Filiz, V. %D 2014 %J Langmuir %N 29 %P 8907-8914 %R doi:10.1021/la501478s %T Postmodification of PS-b-P4VP Diblock Copolymer Membranes by ARGET ATRP %U https://doi.org/10.1021/la501478s 29 %X The surfaces of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer membranes were modified in order to obtain polymer brushes by using surface-initiated Activators Regenerated by Electron Transfer Atom Transfer Radical Polymerization (ARGET ATRP) . Isoporous membranes were prepared by the combination of self-assembly of PS-b-P4VP diblock copolymers and the nonsolvent induced phase separation process, also known as “phase inversion”. In order to allow further functionalization the membranes were modified with an ATRP initiator, 2-bromoisobutyryl bromide (BIBB). Therefore, the mussel-inspired poly(dopamine) coating was used to attach BIBB on the membranes surface. In the next step the coated membranes were post-modified by using surface-initiated ARGET ATRP with the hydrophilic monomer 2-hydroxyethyl methacrylate (HEMA). The surface-initiated ARGET ATRP reaction was carried out under different reaction times and environments. PHEMA could successfully incorporate on the membrane surface as confirmed by attenuated total relection Fourier Transform infrared spectroscopy (ATR-FTIR), 1H-nuclear magnetic resonance spectroscopy (1H-NMR), scanning electron microscopy (SEM), and contact angle measurements, respectively. Furthermore stability tests against heat and solvents were performed and water flux was measured for raw and modified membranes. %0 journal article %@ 2046-2069 %A Khan, M.M.,Bengtson, G.,Neumann, S.,Rahman, M.M.,Abetz, V.,Filiz, V. %D 2014 %J RSC Advances %N 61 %P 32148-32160 %R doi:10.1039/c4ra03663h %T Synthesis, characterization and gas permeation properties of anthracene maleimide-based polymers of intrinsic microporosity %U https://doi.org/10.1039/c4ra03663h 61 %X A series of new monomers containing dialkyl anthracene maleimide derivatives [4a,b(I–V)], which can be used as a precursor of a polymer of intrinsic microporosity (PIM) has been synthesized and characterized successfully. The homopolymers prepared via polycondensation with 2,3,5,6,-tetrafluoroterephthalonitrile (TFTPN) and their copolymers in combination with 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane (TTSBI) were characterized by SEC, FT-IR, TGA, 1H-NMR, BET-surface area and gas transport properties. Compared to polymers derived from 4a(I–V) monomers, the homopolymers and copolymers obtained from 4b(I–V) show improved solubility in common organic solvents and have high average molecular weight. Therefore they are able to form robust and transparent films. The gas transport properties of homopolymers and copolymers of 4b(I–V) show enhanced selectivity compared to PIM-1 for gas pairs such as O2/N2, CO2/N2 and CO2/CH4, followed by a slight decrease in permeability. The introduction of anthracene maleimide units (especially 4bIII) in the copolymer leads to more efficient chain packing and gives the copolymer a similar pore width distribution as PIM-1. As a consequence, the introduction of anthracene maleimide enhanced the CO2 selectivity of copolymers, compared to previously reported film forming polymers. Therefore, these polymers might be useful for gas separations relying on CO2 selectivity. %0 journal article %@ 1226-119X %A Haenelt, T.G.,Georgopanos, P.,Abetz, C.,Rangou, S.,Alisch, D.,Meyer, A.,Handge, U.A.,Abetz, V. %D 2014 %J Korea-Australia Rheology Journal %N 3 %P 263-275 %R doi:10.1007/s13367-014-0031-3 %T Morphology and elasticity of polystyrene-block-polyisoprene diblock copolymers in the melt %U https://doi.org/10.1007/s13367-014-0031-3 3 %X The influence of morphology on the viscoelastic properties of melts of microphase-separated polystyrene-block-polyisoprene (PS-b-PI) diblock copolymers was investigated in oscillatory shear and creep recovery experiments. By means of anionic polymerization, three PS-b-PI diblock copolymers with a narrow molecular weight distribution and different types of morphology (spherical, cylindrical and lamellar microstructure) were prepared. Linear viscoelastic shear oscillations and creep recovery experiments in shear were performed in order to determine the elastic and viscous properties of the diblock copolymers in the melt at small and large time scales. Our analysis reveals that melts of diblock copolymers are characterized by a pronounced elastic behavior leading to a relatively large recoverable deformation in creep recovery experiments. The elasticity of the diblock copolymers is also revealed by the appearance of the creep-ringing effect. Morphological investigations were carried out to establish relations between microstructure and melt elasticity. Since ordering phenomena take place in melts of diblock copolymers until an equilibrium morphology is achieved, the storage modulus G′ of diblock copolymer melts increases with time up to a steady-state value. %0 journal article %@ 0376-7388 %A Rahman, M.M.,Shishatskiy, S.,Abetz, C.,Georgopanos, P.,Neumann, S.,Khan, M.M.,Filiz, V.,Abetz, V. %D 2014 %J Journal of Membrane Science %N %P 344-354 %R doi:10.1016/j.memsci.2014.06.048 %T Influence of temperature upon properties of tailor-made PEBAX® MH 1657 nanocomposite membranes for post-combustion CO2 capture %U https://doi.org/10.1016/j.memsci.2014.06.048 %X Tailor-made block copolymer nanocomposite membranes are prepared by incorporation of 40 wt% methoxy poly(ethylene glycol) (PEG) functionalized polyoctahedral oligomeric silsesquioxanes (POSS) nanoparticles in commercial thermoplastic elastomer multiblock copolymer PEBAX® MH 1657. Atomic force microscopy was used to find out the location of the nanoparticles in the block copolymer matrix. Separation of CO2 from N2 and H2 is studied by measurements of single gas transport properties of nanocomposite materials using the time-lag method in the temperature range 30–70 °C. PEG functionalized POSS nanoparticles increase the CO2 permeability of the nanocomposite membranes without loss of CO2/N2 and CO2/H2 selectivity. Thermal properties of the nanocomposite membranes are studied by differential scanning calorimetry (DSC) to assess the stability of the nanocomposite membranes upon melting of polyether and polyamide blocks. %0 journal article %@ 0261-3069 %A Junior, W.S.,Handge, U.A.,dos Santos, J.F.,Abetz, V.,Amancio-Filho, S.T. %D 2014 %J Materials and Design %N %P 246-250 %R doi:10.1016/j.matdes.2014.07.050 %T Feasibility study of friction spot welding of dissimilar single-lap joint between poly(methyl methacrylate) and poly(methyl methacrylate)-SiO2 nanocomposite %U https://doi.org/10.1016/j.matdes.2014.07.050 %X In this work, the feasibility of friction spot welding (FSpW) of a commercial poly(methyl methacrylate) (PMMA) GS grade and a PMMA 6 N/2 wt% silica (SiO2) nanocomposite was investigated. Single-lap joints welded at rotational speeds of 1000, 2000 and 3000 rpm were produced. The analysis of the joint microstructure and material flow pattern indicated that joints could be produced using all of the tested welding conditions. However, the joint produced at 1000 rpm displayed sharp weld lines (weak links), indicating insufficient heat input, while the welds produced at 3000 rpm displayed excessive plastic deformation (bulging of the bottom plate), volumetric defects and a lack of material mixing in the welded area, associated with higher heat input. The weld produced at a rotational speed of 2000 rpm resulted in improved material mixing, which was indicated by the absence of weld lines and volumetric defects due to the more correct heat input. This welding condition was selected for further mechanical testing. Lap shear testing of PMMA GS/PMMA 6 N/2 wt% SiO2 nanocomposite single lap joints welded at 2000 rpm resulted in an average ultimate lap shear strength of 3.9 ± 0.05 MPa. These weld strength values are equal to or better than those obtained using state-of-the-art welding techniques for PMMA materials, thereby demonstrating the potential of friction spot welding for thermoplastic nanocomposites. %0 journal article %@ 0032-3861 %A Junior, W.S.,Emmler, T.,Abetz, C.,Handge, U.A.,dos Santos, J.F.,Amancio-Filho, S.T.,Abetz, V. %D 2014 %J Polymer %N 20 %P 5146-5159 %R doi:10.1016/j.polymer.2014.08.022 %T Friction spot welding of PMMA with PMMA/silica and PMMA/silica-g-PMMA nanocomposites functionalized via ATRP %U https://doi.org/10.1016/j.polymer.2014.08.022 20 %X In the present study, the feasibility of Friction Spot Welding (FSpW) of a commercial-grade poly(methyl methacrylate) (PMMA) (PMMA GS) and PMMA 6N/functionalized silica (SiO2) nanocomposites was investigated. The silica nanoparticles were functionalized via atom transfer radical polymerization (ATRP) with PMMA chains to achieve a uniform dispersion in the polymer matrix. The successful functionalization of silica nanoparticles with PMMA chains via ATRP was evaluated by ATR-FT-IR and TGA measurements. Rheological investigations of the silica nanocomposites showed a plateau of the storage modulus G′ at low frequencies (0.01–0.03 rad/s) as a result of elastic particle–particle interactions. Overlap friction spot welds consisting of PMMA GS and a 2 wt% SiO2-g-PMMA nanocomposite were successfully prepared and compared to spot joints of PMMA GS welded with PMMA 6N and PMMA 6N/silica nanocomposite with 2 wt% unfunctionalized silica nanoparticles. Raman mappings of selected areas of cross-sectional plastographic specimens revealed an increased mixing behavior between the two polymer plates in the case of PMMA GS/2 wt% SiO2-g-PMMA joints. Although the joints welded with PMMA 6N/silica nanocomposites showed a reduction of 22% in lap shear strength and 21% displacement at peak load compared with the neat PMMA spot welds, they can compete with other state-of-the-art PMMA welding techniques such as thermal bonding and ultrasonic welding, which indicates the potential of friction spot welding as an alternative fabrication technology for joining future nanocomposite engineering parts. %0 journal article %@ 0009-286X %A Mushardt, H.,Kramer, V.,Huelague, D.,Brinkmann, T.,Kraume, M. %D 2014 %J Chemie - Ingenieur - Technik %N 1-2 %P 83-91 %R doi:10.1002/cite.201300074 %T Development of Solubility Selective Mixed Matrix Membranes for Gas Separation %U https://doi.org/10.1002/cite.201300074 1-2 %X A new kind of gas permeation membrane is developed to separate higher hydrocarbons (C3+) from permanent gases. State of the art for such gas permeation applications are membranes based on solubility selective, rubbery polymers, which offer high permeances but relatively low selectivities. The new membrane is designed to improve selectivity, and therefore, significantly reduce energy demand and size of a gas separation plant. The membrane is based on the mixed matrix concept and consists of a rubbery polymer matrix with incorporated activated carbon particles. This two phase separation layer forms a solubility selective mixed matrix membrane by combining the advantages of both materials. The separation of n-C4H10/CH4 mixtures is investigated. Based on experimental results a new concept for a transport model for mixed matrix membrane is introduced. %0 journal article %@ 0024-9297 %A Stegelmeier, C.,Filiz, V.,Abetz, V.,Perlich, J.,Fery, A.,Ruckdeschel, P.,Rosenfeldt, S.,Foerster, S. %D 2014 %J Macromolecules %N 16 %P 5566-5577 %R doi:10.1021/ma5004908 %T Topological Paths and Transient Morphologies during Formation of Mesoporous Block Copolymer Membranes %U https://doi.org/10.1021/ma5004908 16 %X We systematically investigated the structure formation pathways and transient morphologies involved in the formation of mesoporous membranes by the self-assembly of block copolymers during nonsolvent-induced phase separation. Using AFM, SEM, and in situ synchrotron SAXS, we mapped the topological paths and characteristic transient structures into a ternary phase diagram. We focused on the stability region of an ordered pore phase which is relevant for the generation of integral asymmetric isoporous membranes. We could identify several characteristic morphologies, i.e., spinodal networks, sphere percolation networks, ordered pore structures, and disordered and ordered cylinder arrangements together with transient structures connecting their stability regions. With given evaporation rates for the pure solvents, we calculated the corresponding composition trajectories in the phase diagram to identify suitable experimental conditions in terms of initial polymer volume fraction, solvent composition, and immersion time to trap the desired pore structure. %0 journal article %@ 0376-7388 %A Lillepaerg, J.,Georgopanos, P.,Shishatskiy, S. %D 2014 %J Journal of Membrane Science %N %P 269-278 %R doi:10.1016/j.memsci.2014.05.039 %T Stability of blended polymeric materials for CO2 separation %U https://doi.org/10.1016/j.memsci.2014.05.039 %X Reduction of CO2 emission caused by fossil fuel power plants is widely appreciated task. The most suitable materials for off-gas membrane separation process are poly(ethylene glycol) containing polymers. Pebax® 1657 blended with low molecular weight poly(ethylene glycol)s is a promising material for the selective layer of thin film composite gas separation membranes. Stability of blend Pebax® 1657 thick membranes was evaluated at temperatures up to 90 °C, exceeding those at a stack of power plant. The membranes were tested for gas transport properties by thermoanalytical methods. It was found that a threshold of molecular weight exists between 350 and 500 g/mol, at which leaching out of the low molecular weight poly(ethylene glycol) compound from the polymer matrix becomes minimal. Poly(ethylene glycol) with methyl end groups having a molecular weight of 500 g/mol provides a blend material with a CO2 permeability coefficient higher than in case of Polyactive™. PEBAX®/DM500 blend can be a cheaper alternative to tailor made Polyactive™ in large scale production of CO2 selective thin film composite membrane. %0 journal article %@ 2045-2322 %A Zillohu, A,U.,Abdalaziz, R.,Homaeigohar, S.,Krasnov, I.,Mueller, M.,Strunskus, T.,Elbahri, M. %D 2014 %J Scientific Reports %N %P 7407 %R doi:10.1038/srep07407 %T Biomimetic Transferable Surface for a Real Time Control over Wettability and Photoerasable Writing with Water Drop Lens %U https://doi.org/10.1038/srep07407 %X We demonstrate a transferable device that can turn wettability of surfaces to sticky or slippy, as per requirement. It is composed of polymeric yarn with a fibrous structure, which can be lifted and placed on any surface to render it the unique wettability properties. We introduce Polyvinylidenefluoride (PVDF) random fiber as biomimetic rose petal surface. When it is decorated with PVDF nanofibers yarns, the random mesh transform from rose petal sticky state into grass leaf slippy state. When it is placed on sticky, hydrophilic metal coin, it converts the surface of the coin to super hydrophobic. Adjustments in the yarn system, like interyarn spacing, can be done in real time to influence its wettability, which is a unique feature. Next, we load the polymer with a photochromic compound for chemical restructuring. It affects the sliding angle of water drop and makes the fibers optically active. We also demonstrate a “water droplets lens” concept that enables erasable writing on photochromic rose petal sticky fibrous surface. The droplet on a highly hydrophobic surface acts as a ball lens to concentrate light onto a hot spot; thereby we demonstrate UV light writing with water lenses and visible light erasing. %0 journal article %@ 1996-1944 %A Etrich, C.,Fahr, S.,Hedayati, M.K.,Faupel, F.,Elbahri, M.,Rockstuhl, C. %D 2014 %J Materials %N 2 %P 727-741 %R doi:10.3390/ma7020727 %T Effective Optical Properties of Plasmonic Nanocomposites %U https://doi.org/10.3390/ma7020727 2 %X Plasmonic nanocomposites find many applications, such as nanometric coatings in emerging fields, such as optotronics, photovoltaics or integrated optics. To make use of their ability to affect light propagation in an unprecedented manner, plasmonic nanocomposites should consist of densely packed metallic nanoparticles. This causes a major challenge for their theoretical description, since the reliable assignment of effective optical properties with established effective medium theories is no longer possible. Established theories, e.g., the Maxwell-Garnett formalism, are only applicable for strongly diluted nanocomposites. This effective description, however, is a prerequisite to consider plasmonic nanocomposites in the design of optical devices. Here, we mitigate this problem and use full wave optical simulations to assign effective properties to plasmonic nanocomposites with filling fractions close to the percolation threshold. We show that these effective properties can be used to properly predict the optical action of functional devices that contain nanocomposites in their design. With this contribution we pave the way to consider plasmonic nanocomposites comparably to ordinary materials in the design of optical elements. %0 journal article %@ 2195-1071 %A Hedayati, M.K.,Javaheri, M.,Zillohu, A.U.,El-Khozondar, H.J.,Bawa´aneh, M.S.,Lavrinenko, A.,Faupel, F.,Elbahri, M. %D 2014 %J Advanced Optical Materials %N 8 %P 705-710 %R doi:10.1002/adom.201400105 %T Photo-driven Super Absorber as an Active Metamaterial with a Tunable Molecular-Plasmonic Coupling %U https://doi.org/10.1002/adom.201400105 8 %X An optically driven metamaterial with a photoswitchable weak and strong molecular-plasmonic coupling is demonstrated. In this active perfect absorber, the absorption band can be broadened more than 150 nm (split with an energy difference of 780 meV) by UV irradiation, which demonstrates a new class of optically tunable metamaterial absorber for visible frequencies. %0 journal article %@ 0003-6951 %A Hedayati, M.K.,Zillohu, A.U.,Strunskus, T.,Faupel, F.,Elbahri, M. %D 2014 %J Applied Physics Letters %N 4 %P 041103 %R doi:10.1063/1.4863202 %T Plasmonic tunable metamaterial absorber as ultraviolet protection film %U https://doi.org/10.1063/1.4863202 4 %X Plasmonic metamaterials designed for optical frequency have to be shrunk down to few 10th of nanometer which turns their manufacturing cumbersome. Here, we shift the performance of metamaterial down to ultraviolet (UV) by using ultrathin nanocomposite as a tunable plasmonic metamaterial fabricated with tandem co-deposition. It provides the possibility to realize a plasmonic metamaterial absorber for UV frequency with marginal angle sensitivity. Its resonance frequency and intensity can be adjusted by changing thickness and filling factor of the composite. Presented approach for tunable metamaterials for high frequency could pave the way for their application for thermo-photovoltaic, stealth technology, and UV-protective coating. %0 journal article %@ 1996-1944 %A Hedayati, M.K.,Faupel, F.,Elbahri, M. %D 2014 %J Materials %N 2 %P 1221-1248 %R doi:10.3390/ma7021221 %T Review of Plasmonic Nanocomposite Metamaterial Absorber %U https://doi.org/10.3390/ma7021221 2 %X Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon). These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on) perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented. %0 journal article %@ 2040-3364 %A Hedayati, M.K.,Fahr, S.,Etrich, C.,Faupel, F.,Rockstuhl, C.,Elbahri, M. %D 2014 %J Nanoscale %N 11 %P 6037-6045 %R doi:10.1039/c4nr00087k %T The hybrid concept for realization of an ultra-thin plasmonic metamaterial antireflection coating and plasmonic rainbow %U https://doi.org/10.1039/c4nr00087k 11 %X We report on the design, simulation, fabrication, and characterization of a novel two layer anti-reflective coating (ARC) based on a plasmonic metamaterial and a dielectric. Promoted by the strong material dispersion of the plasmonic metamaterial, our novel concept (called hybrid ARC) combines two possible arrangements for layers in an anti-reflection coating into a single structure; albeit at two different wavelengths. This, however, causes a broadband reduction of reflection that is less sensitive against oblique incidence when compared to traditional antireflective coatings. Furthermore, we show that the current metamaterial on a metal reflector can be used for the visualization of different coloration such as plasmonic rainbow despite its sub-wavelength thickness. %0 journal article %@ 1996-1944 %A Zillohu, A.U.,Alissawi, N.,Abdelaziz, R.,Elbahri, M. %D 2014 %J Materials %N 1 %P 323-332 %R doi:10.3390/ma7010323 %T Thermo-Plasmonics for Localized Graphitization and Welding of Polymeric Nanofibers %U https://doi.org/10.3390/ma7010323 1 %X Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon). These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on) perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented. %0 journal article %@ 1022-1352 %A Raue, M.,Wambach, M.,Gloeggler, S.,Grefen, D.,Kaufmann, R.,Abetz, C.,Georgopanos, P.,Handge, U.A.,Mang, T.,Bluemich, B.,Abetz, V. %D 2014 %J Macromolecular Chemistry and Physics %N 3 %P 245-254 %R doi:10.1002/macp.201300629 %T Investigation of Historical Hard Rubber Ornaments of Charles Goodyear %U https://doi.org/10.1002/macp.201300629 3 %X Charles Goodyear discovered the vulcanization process of natural rubber in the middle of the 19th century. In this paper, original ornaments produced by Charles Goodyear are investigated. Additionally, for comparison, a sample is produced according to Goodyear's patent (US 3633) as reference. Contrary to expectation, it is found that Charles Goodyear did not prepare the ornaments using the formulation of his patent, thus he excluded the white lead. Due to this, another reference sample is produced like the other but without white lead. It is proven that by artificial aging, natural rubber samples can get properties similar to the 150 years old rubber sample. %0 journal article %@ 0376-7388 %A Rangou, S.,Buhr, K.,Filiz, V.,Clodt, J.I.,Lademann, B.,Hahn, J.,Jung, A.,Abetz, V. %D 2014 %J Journal of Membrane Science %N %P 266-275 %R doi:10.1016/j.memsci.2013.10.015 %T Self-organized isoporous membranes with tailored pore sizes %U https://doi.org/10.1016/j.memsci.2013.10.015 %X Membrane formation via the combination of self-assembly and the non-solvent induced phase separation (NIPS) process of diblock copolymers is investigated. Several polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers with different molecular weights and weight percentages of both blocks are tested under different parameters, leading to membrane surfaces with uniform pores of approximately 20–70 nm diameter. The average pore diameter is proved to be adjustable by changing the total molar mass of the block copolymer. The solution composition is an additional parameter controlling the structure formation. The purpose was to explore the upper and lower limits of the membrane structure formation by varying the molecular weight and the composition of the block copolymer. Scanning electron microscopy (SEM) is used to image the surface morphology and the homogeneity of the pore sizes. Primary results of water flux and retention are presented. %0 journal article %@ 1438-7492 %A Hahn, J.,Filiz, V.,Rangou, S.,Lademann, B.,Buhr, K.,Clodt, J.I.,Jung, A.,Abetz, C.,Abetz, V. %D 2013 %J Macromolecular Materials and Engineering %N 12 %P 1315-1321 %R doi:10.1002/mame.201300012 %T PtBS-b-P4VP and PTMSS-b-P4VP Isoporous Integral-Asymmetric Membranes with High Thermal and Chemical Stability %U https://doi.org/10.1002/mame.201300012 12 %X Isoporous integral-asymmetric membranes of tailor-made poly(tert-butylstyrene)- and poly(4-trimethylsilylstyrene)-block-poly(4-vinylpyridine) diblock copolymers are reported here for the first time. The membrane development involved the optimization of the production process—which is a combination of block copolymer self-assembly and the non-solvent induced phase inversion process. The membranes showed an improved thermal and chemical stability compared to previously reported polystyrene-block-poly(4-vinylpyridine) membranes, thus the number of potential application areas for such type of isoporous membranes is increased. %0 journal article %@ 1520-6106 %A Enotiadis, A.,Litina, K.,Gournis, D.,Rangou, S.,Avgeropoulos, A.,Xidas, P.,Triantafyllidis, K. %D 2013 %J The Journal of Physical Chemistry B %N 3 %P 907-915 %R doi:10.1021/jp309361b %T Nanocomposites of Polystyrene-b-Poly(isoprene)-b-Polystyrene Triblock Copolymer with Clay-Carbon Nanotube Hybrid Nanoadditives %U https://doi.org/10.1021/jp309361b 3 %X Polystyrene-b-polyisoprene-b-polystyrene (PS-b-PI-b-PS), a widely used linear triblock copolymer of the glassy-rubbery-glassy type, was prepared in this study by anionic polymerization and was further used for the development of novel polymer nanocomposite materials. Hybrid nanoadditives were prepared by the catalytic chemical vapor deposition (CCVD) method through which carbon nanotubes were grown on the surface of smectite clay nanolayers. Side-wall chemical organo-functionalization of the nanotubes was performed in order to enhance the chemical compatibilization of the clay–CNT hybrid nanoadditives with the hydrophobic triblock copolymer. The hybrid clay–CNT nanoadditives were incorporated in the copolymer matrix by a simple solution-precipitation method at two nanoadditive to polymer loadings (one low, i.e., 1 wt %, and one high, i.e., 5 wt %). The resulting nanocomposites were characterized by a combination of techniques and compared with more classical nanocomposites prepared using organo-modified clays as nanoadditives. FT-IR and Raman spectroscopies verified the presence of the hybrid nanoadditives in the final nanocomposites, while X-ray diffraction and transmission electron microscopy proved the formation of fully exfoliated structures. Viscometry measurements were further used to show the successful incorporation and homogeneous dispersion of the hybrid nanoadditives in the polymer mass. The so prepared nanocomposites exhibited enhanced mechanical properties compared to the pristine polymer and the nanocomposites prepared by conventional organo-clays. Both tensile stress and strain at break were improved probably due to better interfacial adhesion of the clay–CNT hybrid of the flexible rubbery PI middle blocks of the triblock copolymer matrix. %0 journal article %@ 1438-7492 %A Haase, A.,Hesse, P.,Brommer, L.,Jacobs, O.,Abetz, C.,Handge, U.A.,Boschetti de Fierro, A.,Abetz, V. %D 2013 %J Macromolecular Materials and Engineering %N 3 %P 292-302 %R doi:10.1002/mame.201200041 %T Modification of Polycarbonate and Glycol Modified Poly(ethylene terephthalate) by Addition of Silica-Nanoparticles Grafted with SAN Copolymer Using “Classical” and ARGET ATRP %U https://doi.org/10.1002/mame.201200041 3 %X This study presents a nanocomposite manufacturing route starting from non-functionalized nanosilica and SAN surface modification via “grafting from” ATRP up to processing of transparent polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites. Synthesis limitations of low molecular weight graft SAN derived from “classical” ATRP are overcome by employment of the emerging ARGET ATRP. Mechanical investigations of polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites present up to 80% enhancement of creep performance and additionally 70% enhancement against wear abrasion for glycol modified poly(ethylene terephthalate) nanocomposites. Strength and tensile modulus are only moderately influenced by the addition of nanoparticles. Morphological studies confirm that the present modification route is able to create uniform dispersions of single particles and small particle aggregates in polymer matrices. %0 journal article %@ 1616-301X %A Clodt, J.I.,Filiz, V.,Rangou, S.,Buhr, K.,Abetz, C.,Hoeche, D.,Hahn, D.,Jung, A.,Abetz, V. %D 2013 %J Advanced Functional Materials %N 6 %P 731-738 %R doi:10.1002/adfm.201202015 %T Double Stimuli-Responsive Isoporous Membranes via Post-Modification of pH-Sensitive Self-Assembled Diblock Copolymer Membranes %U https://doi.org/10.1002/adfm.201202015 6 %X Double stimuli-responsive membranes are prepared by modification of pH-sensitive integral asymmetric polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer membranes with temperature-responsive poly(N-isopropylacrylamide) (pNIPAM) by a surface linking reaction. PS-b-P4VP membranes are first functionalized with a mild mussel-inspired polydopamine coating and then reacted via Michael addition with an amine-terminated pNIPAM-NH2 under slightly basic conditions. The membranes are thoroughly characterized by nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy and X-ray-induced photoelectron spectroscopy. Additionally dynamic contact angle measurements are performed comparing the sinking rate of water droplets at different temperatures. The pH- and thermo-double sensitivities of the modified membranes are proven by determining the water flux under different temperature and pH conditions. %0 journal article %@ 0887-624X %A Pafiti, K.S.,Patrickios, C.S.,Filiz, V.,Rangou, S.,Abetz, C.,Abetz, V. %D 2013 %J Journal of Polymer Science A %N 1 %P 213-221 %R doi:10.1002/pola.26369 %T Styrene-vinyl pyridine diblock copolymers: Achieving high molecular weights by the combination of anionic and reversible addition–fragmentation chain transfer polymerizations %U https://doi.org/10.1002/pola.26369 1 %X Anionic and reversible addition–fragmentation chain transfer (RAFT) polymerizations were combined for the preparation of high molecular weight (MW) amphiphilic diblock copolymers based on the hydrophobic styrene (Sty) and the more polar 2-vinyl pyridine (2VPy) or 4-vinyl pyridine (4VPy). In particular, four amphiphilic Sty-VPy diblock copolymers with MWs up to 271,000 g mol–1 were prepared. For the polymer synthesis, first, living anionic polymerization of Sty using sec-butyl-lithium as initiator in tetrahydrofuran at −70 °C, followed by termination with ethylene oxide were employed for the preparation of OH-functionalized homopolyStys. Subsequently, a modification of the OH-terminal group was performed by the attachment of a 4-cyanopentanoic acid dithiobenzoate chain transfer agent (CTA) group, giving a polySty macroRAFT CTA, which was extended with 2VPy or 4VPy units using RAFT polymerization. Thus, the prepared diblock copolymers comprised a first block which was near-monodisperse in size, and a second more heterogeneous block. All diblock copolymers were characterized in terms of their MWs and compositions by gel permeation chromatography and 1H NMR spectroscopy, respectively, giving results close to the theoretically expected values. Films cast from chloroform solutions of the diblock copolymers were investigated in terms of their bulk morphologies using transmission electron microscopy, which indicated that the minority block consistently formed the discontinuous microphase, spherical or cylindrical. %0 journal article %@ 0887-6266 %A Hahn, J.,Filiz, V.,Rangou, S.,Clodt, J.,Jung, A.,Buhr, K.,Abetz, C.,Abetz, V. %D 2013 %J Journal of Polymer Science B %N 4 %P 281-290 %R doi:10.1002/polb.23209 %T Structure formation of integral-asymmetric membranes of polystyrene-block-Poly(ethylene oxide) %U https://doi.org/10.1002/polb.23209 4 %X For the first time the combination of solution casting and solvent–nonsolvent exchange (phase inversion) has been applied to generate asymmetric membranes with highly ordered hexagonally packed cylinders with perpendicular orientation composed of polystyrene-block-poly(ethylene oxide). The influence of parameters like solvent composition and evaporation time on the membrane formation is presented. The development is based on a study of the solution behavior by dynamic light scattering and the precipitation behavior of the cylinder forming diblock copolymer by turbidity measurements from different solvent and nonsolvent systems. The water flux properties, as an important membrane characteristic, show a time dependent behavior, due to swelling of the polyethylene oxide blocks. The morphologies of the membranes are imaged by scanning electron microscopy. %0 journal article %@ 1022-1336 %A Clodt, J.,Rangou, S.,Schroeder, A.,Buhr, K.,Hahn, J.,Jung, A.,Filiz, V.,Abetz, V. %D 2013 %J Macromolecular Rapid Communications %N 2 %P 190-194 %R doi:10.1002/marc.201200680 %T Carbohydrates as additives for the formation of isoporous PS-b-P4VP diblock copolymer membranes %U https://doi.org/10.1002/marc.201200680 2 %X Highly porous polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer membranes are prepared using carbohydrates as additives. Therefore α-cyclodextrine, α-(D)-glucose, and saccharose (cane sugar) are tested for the membrane formation of three different PS-b-P4VP polymers. The addition of the carbohydrates leads to an increasing viscosity of the membrane solutions due to hydrogen bonding between hydroxyl groups of the carbohydrates and pyridine units of the block copolymer. In all cases, the membranes made from solution with carbohydrates have higher porosity, an improved narrow pore distribution on the surface and a higher water flux as membranes made without carbohydrates with the same polymer, solvent ratio, and polymer concentration. %0 journal article %@ 0032-3861 %A Radjabian, M.,Koll, J.,Buhr, K.,Handge, U.A.,Abetz, V. %D 2013 %J Polymer %N 7 %P 1803-1812 %R doi:10.1016/j.polymer.2013.01.033 %T Hollow Fibre Spinning of Block Copolymers: Influence of Spinning Conditions on Morphological Properties %U https://doi.org/10.1016/j.polymer.2013.01.033 7 %X The self-assembly of block copolymers proposes interesting strategies for design and fabrication of ordered nano/microdomain structures. Recently, large attention has been given to the preparation of porous membranes with cylinder-forming on the top layer of integral asymmetric membranes. In this work, another example of this effort is shown by manufacturing of nanoporous hollow fibre membranes from polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) solutions via phase inversion process. In this way, the self-assembly of block copolymers into an ordered morphology via solvent evaporation is combined with microdomain alignment by shear flow in the die. The influence of the experimental parameters on the morphology of the hollow fibre is discussed, such as type of block copolymer, solution concentration and viscosity, extrusion pressure within the spinneret and air gap distance between the spinneret and the precipitation bath (evaporation time). The evaluation of the surface morphology of the membranes by scanning electron microscopy (SEM) confirms the strong effect of shear flow and solution viscosity on the formation of nanoporous structures in hollow fiber spinning. %0 journal article %@ 0376-7388 %A Khan, M.M.,Filiz, V.,Bengtson, G.,Shishatskiy, S.,Rahman, M.M.,Lillepaerg, J.,Abetz, V. %D 2013 %J Journal of Membrane Science %N %P 109-120 %R doi:10.1016/j.memsci.2013.02.032 %T Enhanced Gas Permeability by Fabricating Mixed Matrix Membranes of Functionalized Multiwalled Carbon Nanotubes and Polymers of Intrinsic Microporosity (PIM) %U https://doi.org/10.1016/j.memsci.2013.02.032 %X In this study, mixed matrix membranes (MMM) consisting of multi-walled carbon nanotubes (MWCNTs) embedded in PIM-1 matrix have been fabricated via solution casting method and their gas transport properties are investigated. The MWCNTs were chemically functionalized with polyethylene glycol (PEG) for a better dispersion in the polymer matrix. The effect of functionalized MWCNTs (f-MWCNTs) loading on gas permeation properties of the MMM were investigated by varying the MWCNTs loading in a PIM-1 matrix from 0.5–3.0 wt %. The derived MMM were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and single gas permeation tests. Gas permeation measurements showed that MMM incorporated with modified and non-modified CNTs exhibited different gas separation performance. The f-MWCNT MMM show better performance compared to MMM with non-modified CNTs in terms of dispersion and permeability at 2 wt% f-MWCNTs loading without sacrificing selectivity. According to diffusivity and solubility data derived from the time-lag method, the PEG chains on MWCNTs show interaction with CO2 as indicated by an increase of the solubility of the polar gas and a reduction of the solubility of non-polar gas, which is advantageous for CO2/N2 separation. The mechanical properties and experimental sorption isotherms of CO2 and N2 of the f-MWCNTs/PIM MMM were enhanced as well. %0 journal article %@ 0032-3861 %A Kabir, R.,Albuerne, J.,Simon, P.F.W.,Filiz, V.,Abetz, C.,Boettcher, H.,Perlich, J.,Abetz, V. %D 2013 %J Polymer %N 2 %P 673-684 %R doi:10.1016/j.polymer.2012.11.075 %T Deformation and orientation behavior of polystyrene-b-polybutadiene-b-poly(methyl methacrylate) triblock terpolymers: Influence of polybutadiene microstructures and the molar masses %U https://doi.org/10.1016/j.polymer.2012.11.075 2 %X Morphological changes caused by deformation and orientation of different domains of polystyrene-b-polybutadiene-b-poly(methyl methacrylate), SBM, triblock terpolymers were investigated using in-situ small angle X-ray scattering (SAXS), tensile testing, and transmission electron microscopy (TEM). Two sets of SBM triblock terpolymers with similar weight fractions of the three blocks were studied. The two sets differ in terms of their molecular weights. Each set contained two SBM differing in their polybutadiene isomers (1,2- and 1,4-B). Results showed that for 1,2-B based SBMs the polybutadiene block forms cylindrical domains which coalesce in the glassy lamellar matrix of the two glassy outer blocks whereas the lower molar mass 1,4-B based SBM forms mixed S/M and the higher one forms well segregated long range ordered lamellae. These morphological differences indicate that the deformation and the orientation behavior of the polymers' domains differ. In 1,2-B based SBMs yielding at high stresses was followed by a stress drop after the yield point. The other polymer type showed homogeneous deformation of the lamellar domains at their yield point. 2D-SAXS during deformation of the triblock terpolymers showed an anisotropic deformation pattern in the 1,2-B SBMs, whereas four point SAXS patterns were found for the 1,4-B SBMs. Further studies showed that the fragmented lamellar planes of the lower molar mass 1,2-SBM oriented randomly whereas the orientation of the lamellar planes of the higher molar mass 1,2-B SBM was parallel to the strain direction. The alignment of the lamellar planes of 1,4-B SBMs were randomly distributed in the unstretched state. %0 journal article %@ 1936-0851 %A Hu, H.,Rangou, S.,Kim, M.,Gopalan, P.,Filiz, V.,Avgeropoulos, A.,Osuji, C.O. %D 2013 %J ACS Nano %N 4 %P 2960-2970 %R doi:10.1021/nn400279a %T Continuous Equilibrated Growth of Ordered Block Copolymer Thin Films by Electrospray Deposition %U https://doi.org/10.1021/nn400279a 4 %X Deposition of block copolymer thin films is most often accomplished in a serial process where material is spin coated onto a substrate and subsequently annealed, either thermally or by solvent vapor, to produce a well-ordered morphology. Here we show that under appropriate conditions, well-ordered block copolymer films may be continuously grown under substrate equilibrated conditions by slow deposition of discrete subattoliter quantities of material using electrospray. We conduct time-resolved observations and investigate the effects of process parameters that underpin film morphology including solvent selectivity, substrate temperature, block-substrate selectivity, and flow rate of the feed solution. For a PEO cylinder-forming poly(styrene-b-ethylene oxide) block copolymer, we uncover a wide temperature window from 90 to 150 °C and an ideal flow rate of 2 μL/min for ordered film deposition from dilute acetone solutions. PEO cylinders aligned with their long axes perpendicular to the film–air interface at optimal spray conditions. Using poly(styrene-b-methyl methacrylate) deposited onto neutrally selective surfaces, we show that the substrate-equilibrated process results in vertically oriented microdomains throughout the film, indicating a preservation of the initial substrate-dictated morphology during the film deposition. Electrospray offers a new and potentially exciting route for controlled, continuous growth of block copolymer thin films and manipulation of their microstructure. %0 journal article %@ 1520-6106 %A Chen, S.,Yi, W.,Duhamel, J.,Heinrich, K.,Bengtson, G.,Fritsch, D. %D 2013 %J The Journal of Physical Chemistry B %N 17 %P 5249-5260 %R doi:10.1021/jp307173k %T Effect of the Porosity of a Polymer of Intrinsic Microporosity (PIM) on Its Intrinsic Fluorescence %U https://doi.org/10.1021/jp307173k 17 %X The photophysical properties of a polymer of intrinsic microporosity, namely PIM-1, were characterized by steady-state and time-resolved fluorescence for solutions of PIM-1 in dichloromethane (DCM) or for a membrane made of PIM-1 immersed in hexane to which a quencher was added. Quenching of PIM-1 by the proton-donor trifluoroacetic acid (TFA), electron-rich tributylamine (TBA), and electron-poor nitromethane (CH3NO2) was investigated and compared to those of the structural unit of PIM-1, the model compound M-1. Only TBA and TFA appeared to quench PIM-1 effectively. The sensitivity of monomer M-1 to the nature of the solvent led us to investigate how addition of a quencher would affect the fluorescence of the polymer PIM-1. Solvent effects were observed for TFA only and were carefully characterized. In particular, it was determined that these solvent effects could be neglected for TFA concentration smaller than 1.4 mM. Quenching of PIM-1 by TBA was diffusional in nature and occurred in a similar manner for M-1 and PIM-1 in DCM, suggesting that M-1 is locally excited in PIM-1. All M-1 units were accessible and quenched effectively by TBA for PIM-1 in DCM and the PIM-1 membrane in hexane. Quenching of PIM-1 in DCM and in the membrane was more complex showing a combination of static, diffusive, and protective quenching. The fraction of accessible M-1 units to TFA (fa) was determined to equal 0.5 for PIM-1 in DCM or in the membrane. The TBA and TFA quenching experiments led to the conclusion that the same accessibility was obtained for the fluorescent constituting units of PIM-1 dissolved in DCM or in a membrane immersed in hexane, in agreement with the known high microporosity of this polymer. %0 journal article %@ 0376-7388 %A Rahman, M.M.,Filiz, V.,Shishatskiy, S.,Abetz, C.,Neumann, S.,Bolmer, S.,Khan, M.M.,Abetz, V. %D 2013 %J Journal of Membrane Science %N %P 286-297 %R doi:10.1016/j.memsci.2013.03.001 %T PEBAX® with PEG functionalized POSS as nanocomposite membranes for CO2 separation %U https://doi.org/10.1016/j.memsci.2013.03.001 %X Nanocomposite membranes were prepared by incorporation of commercial poly(ethylene glycol) functionalized polyoctahedral oligomeric silsesquioxanes (PEG-POSS) in two grades of poly(ether-block-amide) namely PEBAX® MH 1657 and PEBAX® 2533. Single gas permeabilities of N2, O2, CH4, H2, and CO2 were measured using the time-lag method. CO2 permeability increased two fold after incorporation of 30 wt% PEG-POSS in PEBAX® MH 1657, while the selectivity was not significantly affected at 30 °C. Simultaneous enhancement in permeability and selectivity was observed up to 30 wt% loading of PEG-POSS in PEBAX® 2533 at 30 °C. The effect of temperature upon CO2 permeability and CO2 selectivity over N2, O2, CH4 and H2 was studied between 30 °C to 70 °C. Substantial influence upon the thermal transition of the polyether domain of both polymers was observed due to incorporation of PEG-POSS by differential scanning calorimetry (DSC). Atomic force microscopy was used to evaluate the impact of 30 wt% PEG-POSS loading upon the surface topography of both investigated grades of PEBAX®. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to study the membrane morphology and the distribution of the nanofillers (PEG-POSS) in PEBAX® membranes. %0 journal article %@ 0376-7388 %A Topf, M.,Ingram, T.,Mehling, T.,Brinkmann, T.,Smirnova, I. %D 2013 %J Journal of Membrane Science %N %P 32-40 %R doi:10.1016/j.memsci.2013.05.003 %T Product recovery in surfactant-based separation processes: Pervaporation of toluene from concentrated surfactant solutions %U https://doi.org/10.1016/j.memsci.2013.05.003 %X Aqueous micellar two-phase systems have been proposed for the cloud point extraction (CPE) of hazardous compounds or high valued products from aqueous solutions. The efficiency of the CPE strongly depends on the reuse of surfactant as well as the product recovery from the coacervate phase. In this work the membrane process pervaporation was successfully applied to remove contaminants from concentrated surfactant solutions. Experimental results show that a polyoctylmethylsiloxane membrane is the most suitable membrane to separate toluene from a 20 wt% Triton X-114 solution. Furthermore, it is demonstrated that trans-membrane fluxes decrease with increasing surfactant concentration. In case of toluene no correlation between concentration and depletion rate was observed. However, it was observed, that the viscosity of the solution is highly influenced by toluene concentration and thus, effects the efficiency of the pervaporation process. To improve the pervaporation performance the influence of temperature and volumetric flow rate on the depletion rate was investigated. The toluene depletion from surfactant-rich solution increases from 30.2% to 55.1% after 200 minutes by optimizing these parameters. The presented results show that the product recovery after the cloud point extraction can successfully be fulfilled by pervaporation. Compared to alternative separation methods no loss of surfactant or excessive foaming was observed in any of the experiments. %0 journal article %@ 0009-286X %A Brinkmann, T.,Pohlmann, J.,Withalm, U.,Wind, J.,Wolff, T. %D 2013 %J Chemie - Ingenieur - Technik %N 8 %P 1210-1220 %R doi:10.1002/cite.201200238 %T Theoretical and Experimental Investigations of Flat Sheet Membrane Module Types for High Capacity Gas Separation Applications %U https://doi.org/10.1002/cite.201200238 8 %X Gas permeation is increasingly considered for high capacity applications. This contribution discusses the commonly employed membrane module types for flat sheet membranes and suggests a new module concept. The applications considered are the separation of CO2 from flue gas and hydrocarbon dewpointing of natural gas. Rigorous models for predicting the operating performance of the module types are described. Pilot plant experiments were conducted to validate the model for envelope type modules. Simulation studies were carried out to predict the performances of the different module types for the two examples and assess their advantages and disadvantages. %0 journal article %@ 0009-286X %A Song, S.,Esche, E.,Stuenkel, S.,Brinkmann, T.,Wind, J.,Shishatskiy, S.,Wozny, G. %D 2013 %J Chemie - Ingenieur - Technik %N 8 %P 1221-1227 %R doi:10.1002/cite.201200242 %T Energy, Equipment and Cost Savings by Using a Membrane Unit in an Amine-Based Absorption Process for CO2 Removal %U https://doi.org/10.1002/cite.201200242 8 %X A hybrid system consisting of a membrane unit and an amine-based process for CO2 removal in the oxidative coupling of methane is investigated experimentally and in simulations. Absorption processes with two different absorbents for removing 90 % of CO2 from the feed stream are regarded as benchmarks and compared to the membrane process with respect to potential energy, equipment, and cost reductions. The results show that a membrane unit using polyimide could assist with CO2 capture and lead to a reduction of the consumed energy per kilogram of CO2 by 40 % and also reduce the size of the absorption columns. Alternative processes with a two-step membrane cascade to enhance the recovery of product ethylene are also discussed. %0 journal article %@ 0032-3888 %A Velasquez, E.,Oliva, H.,Mueller, A.J.,Lopez, J.V.,Vega, J.,Meira, G.R.,Wambach, M. %D 2013 %J Polymer Engineering & Science %N 9 %P 1886-1900 %R doi:10.1002/pen.23450 %T Instability of styrene/polystyrene/polybutadiene/polystyrene-beta-polybutadiene emulsions that emulate styrene polymerization in the presence of polybutadiene %U https://doi.org/10.1002/pen.23450 9 %X This article investigates the room temperature demixing of oil-in-oil emulsions containing styrene (St), polybutadiene (PB), a St-butadiene star block copolymer (BC), and two polystyrene (PS) samples of different molecular weights and is a contribution toward a better understanding of the stability/instability of the reaction mixture in a bulk high-impact polystyrene (HIPS) process close to the phase inversion. Twelve bulk prepolymerizations of St in the presence of PB were emulated, at 10%, 15%, and 20% conversion; and with constant grafting efficiencies. All the blends contained 6% in weight of butadiene units. After stirring the blends for 24 h, the decantation demixing process was monitored along 30 days, with daily measurement of the interface levels after appearance of a clear interface. For some of the isolated phases, their unswollen morphologies were observed by transmission electron microscopy. All the isolated phases exhibited macrophase separation into homopolymer- and copolymer-rich macrodomains with lamellar microdomains. The BC showed a greater affinity toward the PS-rich phase. The separation of an independent BC-rich phase in the blends containing the high molar mass PS and at high grafting efficiencies, modifies the idea of the graft- or BC molecules located at the interface of large PS-rich and PB-rich phases. %0 journal article %@ 2041-1723 %A Abdelaziz, R.,Disci-Zayed, D.,Hedayati, M.K.,Poehls, J.-H.,Zillohu, A.U.,Erkartal, B.,Chakravadhanula, V.S.K.,Duppel, V.,Kienle, L.,Elbahri, M. %D 2013 %J Nature Communications %N %P 2400 %R doi:10.1038/ncomms3400 %T Green chemistry and nanofabrication in a levitated Leidenfrost drop %U https://doi.org/10.1038/ncomms3400 %X Green nanotechnology focuses on the development of new and sustainable methods of creating nanoparticles, their localized assembly and integration into useful systems and devices in a cost-effective, simple and eco-friendly manner. Here we present our experimental findings on the use of the Leidenfrost drop as an overheated and charged green chemical reactor. Employing a droplet of aqueous solution on hot substrates, this method is capable of fabricating nanoparticles, creating nanoscale coatings on complex objects and designing porous metal in suspension and foam form, all in a levitated Leidenfrost drop. As examples of the potential applications of the Leidenfrost drop, fabrication of nanoporous black gold as a plasmonic wideband superabsorber, and synthesis of superhydrophilic and thermal resistive metal–polymer hybrid foams are demonstrated. We believe that the presented nanofabrication method may be a promising strategy towards the sustainable production of functional nanomaterials. %0 journal article %@ 0032-3861 %A Du, B.,Handge, U.A.,Wambach, M.,Abetz, C.,Rangou, S.,Abetz, V. %D 2013 %J Polymer %N 22 %P 6165-6176 %R doi:10.1016/j.polymer.2013.08.065 %T Functionalization of MWCNT with P(MMA-co-S) copolymers via ATRP: Influence on localization of MWCNT in SAN/PPE 40/60 blends and on rheological and dielectric properties of the composites %U https://doi.org/10.1016/j.polymer.2013.08.065 22 %X In this work, the localization of functionalized multi-walled carbon nanotubes (MWCNT) with random copolymers of methyl methacrylate and styrene (P(MMA-co-S)) in poly(styrene-co-acrylonitrile)/poly(2, 6-dimethyl-1,4-phenylene ether) blends (SAN/PPE) and its influence on morphological, rheological and dielectric properties of the composites were investigated. P(MMA-co-S) copolymers were grafted onto MWCNT via atom transfer radical polymerization (ATRP). The molecular weight of the copolymers was adjusted by controlling the time of reaction. In SAN/PPE blends, MWCNT grafted with low molecular weight copolymers were predominantly located at the interface of the blend and a few individual tubes were dispersed in the PPE phase. Aggregation of MWCNT was observed nearby the interfacial region because of micellization of grafted copolymers. Aggregation was more pronounced with increasing molecular weight of the grafted P(MMA-co-S) copolymer. In the melt, the composite containing MWCNT with low molecular weight copolymers had higher dynamic moduli than the one with pristine MWCNT. An increasing molecular weight of grafted copolymer led to a softening effect which resulted in a reduction of the moduli of the composite. Although a pronounced enhancement was observed for the composites with pristine MWCNT, only a small increase in electrical conductivity was achieved by adding functionalized MWCNT owing to the poor network formed by functionalized MWCNT in the blends. %0 journal article %@ 1022-1352 %A Gallei, M.,Rangou, S.,Filiz, V.,Buhr, K.,Bolmer, S.,Abetz, C.,Abetz, V. %D 2013 %J Macromolecular Chemistry and Physics %N 9 %P 1037-1046 %R doi:10.1002/macp.201200708 %T The Influence of Magnesium Acetate on the Structure Formation of Polystyrene-block-poly(4-vinylpyridine)-Based Integral-Asymmetric Membranes %U https://doi.org/10.1002/macp.201200708 9 %X The influence of magnesium acetate on the non-solvent-induced phase separation (NIPS) process of amphiphilic polystyrene-block-poly(4-vinylpyridine)s to gain integral-asymmetric membranes is investigated. Highly uniform pores over the large areas of the membrane can be achieved, and the average pore diameter is adjusted by varying the total molar mass of the block copolymers used. These stimuli-responsive membranes, which are solution cast in the absence or the presence of small amounts of magnesium acetate, are directly compared, showing a remarkable effect on the pore structures and their openness. Minor salt addition is considered to influence the polarity of the solvents used in a positive manner such that the NIPS process can be improved significantly. %0 journal article %@ 0024-9297 %A Higuchi, T.,Sugimori, H.,Jiang, X.,Hong, S.,Matsunaga, K.,Kaneko, T.,Abetz, V.,Takahara, A.,Jinnai, H. %D 2013 %J Macromolecules %N 17 %P 6991-6997 %R doi:10.1021/ma401193u %T Morphological Control of Helical Structures of an ABC-Type Triblock Terpolymer by Distribution Control of a Blending Homopolymer in a Block Copolymer Microdomain %U https://doi.org/10.1021/ma401193u 17 %X The control of microphase-separated structures in a poly(styrene-block-butadiene-block-methyl methacrylate) (SBM) was investigated in three dimensions by transmission electron microtomography. Neat SBM self-assembled into a double-helical structure of polybutadiene (PB) domains around hexagonally packed core polystyrene (PS) cylinders in a poly(methyl methacrylate) matrix. When PS homopolymer with a lower molecular weight than that of the PS block in SBM was added to the SBM, the PB domains transformed from double-helical structures to spherical domains, while maintaining the helical trajectories. In contrast, adding a higher molecular weight PS to the SBM changed the helical structures from double- to triple-stranded structures and even to four-stranded structures. The helical structures of the PB domains were strongly affected by the distribution of the blended polystyrenes in the core cylindrical PS domains. %0 journal article %@ 1022-9760 %A Donescu, D.,Corobea, M.C.,Petcu, C.,Spataru, C.I.,Radovici, C.,Majeed, S.,Abetz, V. %D 2013 %J Journal of Polymer Research %N %P 251 %R doi:10.1007/s10965-013-0251-0 %T Polyacrylonitrile-MWCNT hybrids obtained by free radical polymerization in miniemulsions %U https://doi.org/10.1007/s10965-013-0251-0 %X Polyacrylonitrile (PAN) and poly(acrylonitrile-co-vinylcarbazole) (PAN-VK) hybrids were obtained in presence of multiwalled carbon nanotubes (MWCNT) by a one-step free radical polymerization in miniemulsions. MWCNTs, in an unmodified state, as well as MWCNTs functionalized with maleic anhydride or monoethoxy dimethylvinyl silane, were used. The presence of MWCNT increased the molecular weights of the polymers and affected the polydispersity index. The polymers obtained next to the MWCNT showed a high value in their crystallinity index (33 %). The method was proven as an efficient route for dispersing nanotubes in the polymer matrix. Functionalized MWCNTs restrict the transfer reaction to areas next to the walls of the nanotubes during the polymerization and increase the dispersability in the final polymer matrix. MWCNT –polymer hybrids showed perspectives in membrane fabrication, as well as a specific profile, for carbon fibers precursors (with advantages in the three main stages: cyclization, dehydrogenation and decomposition). %0 journal article %@ 0021-9797 %A Homaeigohar, S.,Dai, T.,Elbahri, M. %D 2013 %J Journal of Colloid and Interface Science %N %P 86-93 %R doi:10.1016/j.jcis.2013.05.076 %T Biofunctionalized nanofibrous membranes as super separators of protein and enzyme from water %U https://doi.org/10.1016/j.jcis.2013.05.076 %X Here, we report development of a novel biofunctionalized nanofibrous membrane which, despite its macroporous structure, is able to separate even trace amounts (as low as 2 mg/L) of biomolecules such as protein and enzyme from water with an optimum efficiency of ∼90%. Such an extraordinary protein selectivity at this level of pollutant concentration for a nanofibrous membrane has never been reported. In the current study, poly(acrylonitrile-co-glycidyl methacrylate) (PANGMA) electrospun nanofibers are functionalized by a bovine serum albumin (BSA) protein. This membrane is extraordinarily successful in removal of BSA protein and Candida antarctica Lipase B (Cal-B) enzyme from a water based solution. Despite a negligible non-specific adsorption of both BSA and Cal-B to the PANGMA nanofibrous membrane (8%), the separation efficiency of the biofunctionalized membrane for BSA and Cal-B reaches to 88% and 81%, respectively. The optimum separation efficiency at a trace amount of protein models is due to the water-induced conformational change of the biofunctional agent. The conformational change not only exposes more functional groups available to catch the biomolecules but also leads to swelling of the nanofibers thereby a higher steric hindrance for the solutes. Besides the optimum selectivity, the biofunctionalized membranes are highly wettable thereby highly water permeable. %0 journal article %@ 0032-3861 %A Misichronis, K.,Rangou, S.,Ashcraft, E.,Kumar, R.,Dadmun, M.,Sumpter, B.G.,Zafeiropoulos, N.E.,Mays, J.W.,Avgeropoulos, A. %D 2013 %J Polymer %N 5 %P 1480-1489 %R doi:10.1016/j.polymer.2013.01.005 %T Synthesis, characterization (molecular–morphological) and theoretical morphology predictions of linear triblock terpolymers containing poly(cyclohexadiene) %U https://doi.org/10.1016/j.polymer.2013.01.005 5 %X The synthesis via anionic polymerization of six linear triblock terpolymers with various sequences of blocks such as PS (polystyrene), PB [poly(butadiene)], PI [(poly(isoprene)] and PCHD [poly(1,3-cyclohexadiene)] is reported. The synthesis of the terpolymers was carried out by the use of anionic polymerization with high-vacuum techniques and sequential monomer addition. Molecular characterization of the samples was performed via size exclusion chromatography (SEC) and membrane osmometry (MO) to measure the polydispersity indices and the number-average molecular weights, respectively. Proton nuclear magnetic resonance spectroscopy (1H NMR) was employed to verify the microstructure type for the polydienes, as well as, to calculate the molar composition. Structural characterization of the terpolymers was performed via transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS), and several morphologies were observed including one which has not been reported previously. Real-space self-consistent field theory (SCFT) without a priori knowledge about the symmetry of the periodic structures was used to elucidate the thermodynamics of the synthesized triblock copolymers. %0 journal article %@ 0009-286X %A Matuschewski, H.,Schiffmann, P.,Notzke, H.,Wolff, T.,Schedler, U.,Brinkmann, T.,Repke, J.-U. %D 2013 %J Chemie - Ingenieur - Technik %N 8 %P 1201-1209 %R doi:10.1002/cite.201200245 %T Pilotversuche in der organophilen Pervaporation: Membran, Modul und SimulationEin Gesamtkonzept - Pilot Tests in Organophilic Pervaporation: Membrane, Module and Simulation – An Overall Concept %U https://doi.org/10.1002/cite.201200245 8 %X Die kontinuierlich wachsenden Anforderungen an Produktreinheit und ansteigende Energiekosten erfordern neue, energieeffiziente technologische Ansätze in der chemischen Industrie. Speziell die selektive Abtrennung von organischen Verbindungen aus wässrigen und organischen Mischungen wird in Zukunft eine bedeutende Rolle spielen. Die organophile Pervaporation ist eine innovative Technologie für diese Trennaufgaben. Ein Gesamtkonzept für das Design eines Membranmoduls für die Pervaporation wird präsentiert. Dieses Konzept beinhaltet die Entwicklung einer hoch-selektiven Membran und das Design eines neuen Membranmoduls. Für die strukturierte Simulation der Trennleistung der Membran und des Membranmoduls werden drei sequentielle Modelle erstellt und in einem benutzerfreundlichen Software-Tool implementiert.,The continuously increasing requirements on product purity and rising energy costs make new, energy-efficient technological approaches in the chemical industry necessary. Especially the selective separation of organic compounds from aqueous and organic mixtures will play an important role in the future. Organophilic pervaporation is an innovative technology for this kind of separation tasks. An overall concept for the design of a membrane module for pervaporation is presented. This concept includes the development of a highly selective membrane and the design of a novel membrane module. For a structured simulation of the membrane and module separation performance, a set of three consecutive models is developed and implemented in a user friendly software tool. %0 journal article %@ 0014-3057 %A Khan, M.M.,Bengtson, G.,Shishatskiy, S.,Gacal, B.N.,Rahman, M.M.,Neumann, S.,Filiz, V.,Abetz, V. %D 2013 %J European Polymer Journal %N 12 %P 4157-4166 %R doi:10.1016/j.eurpolymj.2013.09.022 %T Cross-linking of Polymer of Intrinsic Microporosity (PIM-1) via nitrene reaction and its effect on gas transport property %U https://doi.org/10.1016/j.eurpolymj.2013.09.022 12 %X Polymer of Intrinsic Microporosity (i.e. PIM-1) has been crosslinked thermally via nitrene reaction using polyethylene glycol biazide (PEG-biazide) as a crosslinker. The crosslinking temperature was optimized using TGA coupled with FT-IR spectroscopy. The dense membranes containing different ratios of PIM-1 to PEG-biazide were cast from chloroform solution. Crosslinking of PIM-1 renders it insoluble even in excellent solvents for the uncrosslinked polymer. The resulting crosslinked membranes were characterized by FT-IR spectroscopy, TGA and gel content analysis. The influence of crosslinker content on the gas transport properties of PIM-1, its density and fractional free volume (FFV) were investigated. Compared to the pure PIM-1 membrane, the crosslinked PIM-1 membranes showed better gas separation performance especially for CO2/N2, CO2/CH4 and propylene/propane (C3H6/C3H8) gas pairs and as well as suppressed penetrant-induced plasticization under high CO2 pressure. %0 journal article %@ 1022-1336 %A Jung, A.,Filiz, V.,Rangou, S.,Buhr, K.,Merten, P.,Hahn, J.,Clodt, J.,Abetz, C.,Abetz, V. %D 2013 %J Macromolecular Rapid Communications %N 7 %P 610-615 %R doi:10.1002/marc.201200770 %T Formation of Integral Asymmetric Membranes of AB Diblock and ABC Triblock Copolymers by Phase Inversion %U https://doi.org/10.1002/marc.201200770 7 %X The formation of integral asymmetric membranes from ABC triblock terpolymers by non-solvent-induced phase separation is shown. They are compared with the AB diblock copolymer precursors. Triblock terpolymers of polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) with two compositions are investigated. The third block supports the formation of a membrane in a case, where the corresponding diblock copolymer does not form a good membrane. In addition, the hydrophilicity is increased by the third block and due to the hydroxyl group the possibility of post-functionalization is given. The morphologies are imaged by scanning electron microscopy. The influence of the PEO on the membrane properties is analyzed by water flux, retention, and dynamic contact angle measurements. %0 journal article %@ 0887-624X %A Pafiti, K.S.,Patrickios, C.S.,Abetz, C.,Abetz, V. %D 2013 %J Journal of Polymer Science A %N 23 %P 4957-4965 %R doi:10.1002/pola.26936 %T High-molecular-weight symmetrical multiblock copolymers: Synthesis by RAFT polymerization and characterization %U https://doi.org/10.1002/pola.26936 23 %X High-molecular-weight (MW) symmetrical multiblock copolymers, based on the hydrophobic monomers styrene (Sty) and methyl methacrylate (MMA), and the more polar monomer, 2-vinyl pyridine (2VPy), were prepared using stepwise reversible addition-fragmentation chain transfer polymerization. All copolymers shared a common poly(ethylene glycol) (PEG) midblock, introduced as a bifunctional macromolecular chain transfer agent. In total, five ABA triblock copolymers, five ABCBA pentablock terpolymers, and two ABCDCBA heptablock quaterpolymers (comprising four different monomer types) were synthesized. The MWs of the multiblock polymers were determined using gel permeation chromatography (GPC) and proton nuclear magnetic resonance (1H NMR) spectroscopy, with the latter values being closer to the theoretically expected, whereas GPC MW distributions were relatively narrow, broadening with the number of blocks. The compositions of the synthesized polymers, as determined by 1H NMR spectroscopy, were also close to the expected values. Finally, films cast from chloroform solutions of the pentablock terpolymers P2VPy-b-PSty-b-PEG-b-PSty-b-P2VPy, PSty-b-PMMA-b-PEG-b-PMMA-b-PSty, and P2VPy-b-PMMA-b-PEG-b-PMMA-b-P2VPy examined using transmission electron microscopy exhibited PSty and PMMA cylinders (first two) and lamellae (third terpolymer). %0 journal article %@ 2045-9858 %A Homaeigohar, S.,Disci-Zayed, D.,Dai, T.,Elbahri, M. %D 2013 %J Bioinspired, Biomimetic and Nanobiomaterials %N 4 %P 186-193 %R doi:10.1680/bbn.13.00006 %T Biofunctionalized nanofibrous membranes mimicking carnivorous plants %U https://doi.org/10.1680/bbn.13.00006 4 %X A novel biofunctionalized nanofibrous membrane is developed through immobilization of protein ligands on the surface of nanofibers. The biofunctionalization not only enhances the membrane’s structural properties including mechanical and thermal ones but also makes the membrane capable to separate nanoparticles and biomolecules much smaller than the pore size from water efficiently. Upon contact with water, the conformational change of the protein immobilized leads to its swelling, thereby an enlarged functional surface area and a higher steric hindrance capturing the filtrates. In case of filtration of a plasmonic nanoparticle containing suspension, decoration of the membrane with the plasmonic nanoparticles forms a smart bionanocomposite biosensor for detection of protein denaturation. %0 journal article %@ 1618-8357 %A Abetz, V.,Hausmann, J. %D 2013 %J Ingenieurwissenschaften - Im Fokus: WAK %N %P 34-37 %T Polymere und hybride Werkstoffe: Interdisziplinär weiter entwickeln - DGM-Fachausschuesse fördern Vernetzung %U %X Die Deutsche Gesellschaft für Materialkunde e.V. (DGM) ist europaweit die größte technisch-wissenschaftliche Fachgesellschaft der Materialwissenschaft und Werkstofftechnik. Seit über 90 Jahren bündelt sie die Kompetenzen des Fachbereichs aus Wissenschaft und Industrie. Bereits Mitte der 1980er Jahre führte die zunehmende Substitution von metallischen Materialien durch hochleistungsfähigere polymere Werkstoffe und Verbundwerkstoffe zur Gründung eines DGM-,Fachausschusses zu Polymerwerkstoffen. 2012 folgte dann der Fachausschuss,„Hybride Werkstoffe und Strukturen“, in dem die Erkenntnisse aus den Faserkunststoffverbunden,mit denen aus der Metallkunde zusammengeführt werden. %0 journal article %@ 0032-3861 %A Chakkalakal Louis, G.,Abetz, C.,Vainio, U.,Handge, U.A.,Abetz, V. %D 2013 %J Polymer %N 15 %P 3860-3873 %R doi:10.1016/j.polymer.2013.05.025 %T Influence of rheology and morphology on foaming of PS-b-PMMA diblock copolymers and their composites with modified silica nanoparticles %U https://doi.org/10.1016/j.polymer.2013.05.025 15 %X In this study, the influence of rheological and morphological properties on the foaming behaviour of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymers and their composites with PMMA modified silica nanoparticles is discussed. The blowing agent was carbon dioxide. Cylindrical and lamellar types of PS-b-PMMA diblock copolymers with different molecular weights were chosen in order to elucidate the influence of morphology and molecular weight on the foaming behaviour. The microphase-separated morphology of the diblock copolymers was studied by small-angle x-ray scattering and microscopic investigations. The rheological behaviour of the materials under shear was analysed using linear viscoelastic shear oscillations and creep experiments in order to probe the microstructure at different time scales. High pressure differential scanning calorimetry measurements indicate that the blowing agent carbon dioxide was dissolved in the PS and in the PMMA domains. Generally, the diblock copolymers of our study with a cylindrical morphology led to foams with a lower density than the ones with a lamellar morphology. This effect indicates that large stresses are necessary to deform lamellar structures during nucleation and expansion of foam cells. The diblock copolymer with a cylindrical morphology and polystyrene as the matrix was associated with an ω-independent plateau at low frequencies of the shear oscillations. After foaming, the cell walls and the surface of the foamed PS-b-PMMA diblock copolymer with the polystyrene matrix depicted the cylindrical morphology of the microphase-separated structure. %0 journal article %@ 0376-7388 %A Majeed, S.,Fierro, D.,Buhr, K.,Wind, J.,Du, B.,Boschetti de Fierro, A.,Abetz, V. %D 2012 %J Journal of Membrane Science %N %P 101-109 %R doi:10.1016/j.memsci.2012.02.029 %T Multi-walled carbon nanotubes (MWCNTs) mixed polyacrylonitrile (PAN) ultrafiltration membranes %U https://doi.org/10.1016/j.memsci.2012.02.029 %X Hydroxyl functionalized multi-walled carbon nanotubes (MWCNTs) were blended with polyacrylonitrile (PAN) to prepare ultrafiltration membranes by a phase inversion process. Three different concentrations of MWCNTs were used in PAN, i.e. 0.5, 1 and 2 wt%. The water flux of the membranes increased by 63% at 0.5 wt% loading of MWCNTs compared to neat PAN membranes. The water flux decreased upon further increase in the concentration of MWCNTs, but at 2 wt% loading it was still higher compared to pure PAN membranes. The surface hydrophilicity of the membranes was enhanced upon the addition of MWCNTs, as observed by contact angle measurements. The increased hydrophilicity might have an impact on the improved water flux. All the membranes showed a molecular weight cut off (MWCO) of approximately 50 kg/mol. Surface pore size analysis by scanning electron microscopy (SEM) showed no significant difference in the mean pore size of the nanocomposite membranes compared to the neat membranes. The cross section morphology was influenced by the introduction of MWCNTs where less but enlarged macrovoids were observed, particularly prominent at a loading of 2 wt% MWCNTs. The membranes containing 2 wt% MWCNTs showed 36% improvement in resistance against compaction compared to neat membranes. Furthermore, the tensile strength of the membranes at 2 wt% MWCNTs loading increased over 97% compared to neat ones. %0 journal article %@ 0376-7388 %A Fierro, D.,Boschetti de Fierro, A.,Abetz, V. %D 2012 %J Journal of Membrane Science %N %P 91-101 %R doi:10.1016/j.memsci.2012.04.027 %T The Solution-Diffusion with Imperfections Model as a Method to Understand Organic Solvent Nanofiltration of Multicomponent Systems %U https://doi.org/10.1016/j.memsci.2012.04.027 %X The solution-diffusion with imperfections model has been used together with diffusion models such as the Vrentas & Duda diffusion theory and the Wesselingh & Bollen multicomponent diffusion model as a tool to successfully describe the permeation behavior of mixtures of ketones and glycols through polydimethylsiloxane composite membranes in a cross-flow membrane cell for pressures varying from 10 to 40 bar. The model has shown the great importance of an accurate determination of the diffusion coefficients and the average concentration of permeants inside the membrane into the successful modeling of nanofiltration experiments. %0 journal article %@ 1557-1955 %A Beyene, H.T.,Chakravadhanula, V.S.K.,Hanisch, C.,Strunskus, T.,Zaporojtchenko, V.,Elbahri, M.,Faupel, F. %D 2012 %J Plasmonics %N 1 %P 107-114 %R doi:10.1007/s11468-011-9282-8 %T Vapor Phase Deposition, Structure, and Plasmonic Properties of Polymer-Based Composites Containing Ag–Cu Bimetallic Nanoparticles %U https://doi.org/10.1007/s11468-011-9282-8 1 %X Nanocomposite (NC) thin films with noble metal nanoparticles embedded in a dielectric material show very attractive plasmonic properties due to dielectric and quantum confinement effects. For single component nanoparticles (NPs), the plasmon resonance frequency can only be tuned in a narrow range. Much interest aroused in bimetallic nanoparticles (BNPs), however many wet chemical approaches do not allow large variation of the NP alloy composition and filling factor. Here, we report a vapor phase co-deposition method to produce polymer–metal NCs with embedded Ag1 − x Cu x alloy particles. The method allows production of NPs with controlled alloy composition (x), metal filling (f) and nanostructure in a protecting Teflon AF matrix. The nanostructure size and shape were characterized by transmission electron microscope. Energy dispersive X-ray spectroscopy was used to determine x and f. The optical properties and the position of surface plasmon resonances were studied by UV–Vis spectroscopy. The plasmon resonances can be tuned over a large range of the visible spectrum associated with the change in x, f, and nanostructure. For low filling factors and small particle sizes, only one resonance peak was observed. This is attributed to enhanced miscibility at the nanoscale. Double plasmon resonances were seen for larger particle sizes in accord with phase separation expected from the bulk phase diagram and were explained in terms of the formation of core-shell structures with Cu core and Ag shell. Changes upon annealing at 200 °C are also reported. %0 journal article %@ 0032-3896 %A Hong, S.,Higuchi, T.,Sugimori, H.,Kaneko, T.,Abetz, V.,Takahara, A.,Jinnai, H. %D 2012 %J Polymer Journal %N %P 567-572 %R doi:10.1038/pj.2012.69 %T Highly oriented and ordered double-helical morphology in ABC triblock terpolymer films up to micrometer thickness by solvent evaporation %U https://doi.org/10.1038/pj.2012.69 %X A triblock terpolymer, polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM), formed a double-helical nanoscale structure, composed of polybutadiene (PB) helical microdomains around hexagonally packed polystyrene (PS) cores in a poly(methyl methacrylate) matrix. The orientation of double-helical morphologies at various film thicknesses were studied using transmission electron microtomography, following solvent annealing and drying at a controlled solvent evaporation rate. The evaporation rate of the solvent and the film thickness were important factors in whether the double-helical microdomains were oriented parallel or perpendicular with respect to the substrate. In some cases, the perpendicularly aligned double-helical morphology extended several micrometers from the substrate to the air surface. A similar experiment using polystyrene-block-poly(methyl methacrylate) diblock copolymer proved that the presence of helical PB microdomains around PS cylinders is the key factor in achieving a uniform orientation over several micrometers throughout the film thickness. %0 journal article %@ 1022-1352 %A Chakkalakal Louis, G.,Alexandre, M.,Abetz, C.,Boschetti de Fierro, A.,Abetz, V. %D 2012 %J Macromolecular Chemistry and Physics %N 5 %P 513-528 %R doi:10.1002/macp.201100625 %T Surface Initiated Controlled Radical Polymerisation From Silica Nanoparticles of High Initiator Density %U https://doi.org/10.1002/macp.201100625 5 %X The surface of silica nanoparticles is modified using the “grafting from” technique. A multi-step reaction is conducted to modify their surface properties. (3-glycidoxypropyl) trimethoxysilane (GPS) is used as the coupling agent for the fixation of atom transfer radical polymerization (ATRP) initiator. The grafting efficiency of GPS mixed with aqueous suspension of silica nanoparticles is studied, followed by the coupling efficiency towards ATRP initiator. The bromide concentration of ATRP initiator is kept constant for comparative kinetic studies of styrene and MMA polymerizations. The consequences at high conversions and the particle size distribution are studied. The behaviour of the glass transition temperature of either polymer-modified particles and the nature of dispersion of polymer-coated silica particles are analyzed. %0 journal article %@ 0021-9797 %A Homaeigohar, S.S.,Elbahri, M. %D 2012 %J Journal of Colloid and Interface Science %N 1 %P 6-15 %R doi:10.1016/j.jcis.2012.01.012 %T Novel compaction resistant and ductile nanocomposite nanofibrous microfiltration membranes %U https://doi.org/10.1016/j.jcis.2012.01.012 1 %X Despite promising filtration abilities, low mechanical properties of extraordinary porous electrospun nanofibrous membranes could be a major challenge in their industrial development. In addition, such kind of membranes are usually hydrophobic and non-wettable. To reinforce an electrospun nanofibrous membrane made of polyethersulfone (PES) mechanically and chemically (to improve wettability), zirconia nanoparticles as a novel nanofiller in membrane technology were added to the nanofibers.,The compressive and tensile results obtained through nanoindentation and tensile tests, respectively, implied an optimum mechanical properties after incorporation of zirconia nanoparticles. Especially compaction resistance of the electrospun nanofibrous membranes improved significantly as long as no agglomeration of the nanoparticles occurred and the electrospun nanocomposite membranes showed a higher tensile properties without any brittleness i.e. a high ductility. Noteworthy, for the first time the compaction level was quantified through a nanoindentation test. In addition to obtaining a desired mechanical performance, the hydrophobicity declined. Combination of promising properties of optimum mechanical and surface chemical properties led to a considerably high water permeability also retention efficiency of the nanocomposite PES nanofibrous membranes. Such finding implies a longer life span and lower energy consumption for a water filtration process. %0 journal article %@ 0887-624X %A Zamfir, M.,Patrickios, C.S.,Montagne, F.,Abetz, C.,Abetz, V.,Oss-Ronen, L.,Talmon, Y. %D 2012 %J Journal of Polymer Science A %N 8 %P 1636-1644 %R doi:10.1002/pola.25935 %T Styrene–vinyl pyridine diblock copolymers: Synthesis by RAFT polymerization and self-assembly in solution and in the bulk %U https://doi.org/10.1002/pola.25935 8 %X Reversible addition-fragmentation chain transfer (RAFT) polymerization along with benzyl dithiobenzoate chain transfer agent was employed for the controlled preparation of four diblock copolymers of styrene (St, less polar monomer) and 2- or 4-vinyl pyridine (2VP or 4VP, more polar monomers): St161-b-2VP48, St161-b-2VP121, St161-b-4VP76, and St161-b-4VP107, where the subscripts indicate the experimentally determined degrees of polymerization for each block. These diblock copolymers and their common St homopolymer precursor were characterized in terms of their molecular weights and compositions using gel permeation chromatography and 1H NMR spectroscopy, respectively. All four diblock copolymers self-assembled in dilute toluene solutions to form reverse spherical micelles, which were characterized using atomic force microscopy and cryogenic transmission electron microscopy. Both microscopy techniques revealed that the 4VP-bearing diblock copolymers formed larger micelles than the 2VP-bearing ones, a result of the greater 4VP-toluene incompatibility as compared to the 2VP-toluene one. Finally, films cast from chloroform solutions of the diblocks were investigated in terms of their bulk morphologies using transmission electron microscopy. While the 2VP-containing block copolymer self-assembled into a spherical morphology, the 4VP-containing one with comparable composition and molecular weight formed a cylindrical structure, manifesting the greater 4VP-St incompatibility as compared to that of the 2VP-St pair. %0 conference paper %@ %A Hedayati, M.K.,Javaherirahim, M.,Elbahri, M. %D 2012 %J Proceedings of 3rd International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 12 %N %P 405-408 %T A smart plasmonic transparent conductor with a gas sensing ability %U %X %0 journal article %@ 0024-9297 %A Sultanov, E.Y.,Ezhov, A.A.,Shishatskiy, S.M.,Buhr, K.,Khotimskiy, V.S. %D 2012 %J Macromolecules %N 3 %P 1222-1229 %R doi:10.1021/ma202140c %T Synthesis, Characterization, and Properties of Poly(1-trimethylsilyl-1-propyne)-block-poly(4-methyl-2-pentyne) Block Copolymers %U https://doi.org/10.1021/ma202140c 3 %X Poly(1-trimethylsilyl-1-propyne)-block-poly(4-methyl-2-pentyne) (PTMSP-b-PMP) block copolymers of different composition were synthesized through sequential living polymerization by catalytic systems based on niobium pentachloride with organometallic ... %0 journal article %@ 0026-3672 %A Zenkel, C.,Albuerne, J.,Boschetti de Fierro, A.,Emmler, T.,Helbig, J.,Abetz, V. %D 2012 %J Microchimica Acta %N 1-2 %P 41-48 %R doi:10.1007/s00604-012-0848-8 %T New Strategies for the Chemical Characterization of Multi-Walled Carbon Nanotubes and their Derivatives %U https://doi.org/10.1007/s00604-012-0848-8 1-2 %X Industrially relevant characterization of multi-walled carbon nanotubes (MWCNT) is still remaining a challenging task. The aim of this work is to show novel and fast concepts for the chemical characterization of CNTs by combination of different analytical techniques. While the informations obtained by individual analytical tools like Fourier transform infrared spectroscopy (FTIR), attenuated total reflection infrared spectroscopy (ATR-FTIR), and Raman spectroscopy are not giving a full picture of the functionalisation of the MWCNTs, the combination of analytical tools such as FTIR or mass spectrometry with thermo gravimetric analysis are proven to be very useful methods for the chemical characterisation. Another focus of this contribution is put on sample preparation for FTIR and Raman spectroscopy, as this parameter shows a major influence on the obtained results. Suggestions for the sample preparation leading to results with high reproducibility are given. The measurements have been carried out on typical CNT samples such as commercially available pristine, carboxylated and amine functionalized MWCNTs, but also,polystyrene (PS)-grafted MWCNTs. The results may serve as a guidance for the qualitative and quantitative characterization of CNT. %0 journal article %@ 1438-7492 %A Jung, A.,Rangou, S.,Abetz, C.,Filiz, V.,Abetz, V. %D 2012 %J Macromolecular Materials and Engineering %N 8 %P 790-798 %R doi:10.1002/mame.201100359 %T Structure Formation of Integral Asymmetric Composite Membranes of Polystyrene-block-Poly(2-vinylpyridine) on a Nonwoven %U https://doi.org/10.1002/mame.201100359 8 %X The formation of an integral asymmetric membrane composed of a cylinder-forming polystyrene-block-poly(2-vinylpyridine) on a nonwoven by using solvent casting followed by solvent/nonsolvent exchange (phase inversion) is reported for the first time. The influence of parameters such as solvent composition, evaporation time of the solution-cast block copolymer film before phase inversion, and immersion bath temperature is demonstrated. The optimized membranes are characterized in terms of stimuli-responsive water flux properties. The morphologies of the membranes as well as of the bulk of the block copolymer are imaged by scanning force microscopy, scanning electron microscopy, and transmission electron microscopy. %0 journal article %@ 1438-7492 %A Chakkalakal Louis, G.,Alexandre, M.,Boschetti de Fierro, A.,Abetz, V. %D 2012 %J Macromolecular Materials and Engineering %N 9 %P 887-893 %R doi:10.1002/mame.201100365 %T Effect of Silica-Coated Poly(butyl methacrylate)-block-poly(methyl methacrylate) Double-Shell Particles on the Mechanical Properties of PMMA Composites %U https://doi.org/10.1002/mame.201100365 9 %X Silica nanoparticles with an average diameter of 12 nm are grafted with PBMA-b-PMMA double shells through typical sequential ATRP from bromoisobutyrate initiators anchored at the silica surface using an epoxysilane. A commercially available PMMA homopolymer is used for the preparation of composites with unmodified, silane-modified and double-shell-modified silica particles. Good mechanical properties are obtained for silica double shell containing systems. The silica content in double shell particle systems is varied from 0 to 2.5 wt%. A significant improvement in impact properties is observed. The surface-modified silica particles are characterized by ATR-FTIR, NMR, GPC, and thermal analyses. TEM analysis is used to analyze the nature of dispersion of particles in the composites. %0 conference lecture %@ %A Hedayati, M.K.,Javaherirahim, M.,Elbahri, M. %D 2012 %J 3rd International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 12 %N %P %T A smart plasmonic transparent conductor with a gas sensing ability %U %X %0 journal article %@ 0021-9797 %A Homaeigohar, S.S.,Mahdavi, H.,Elbahri, M. %D 2012 %J Journal of Colloid and Interface Science %N 1 %P 51-56 %R doi:10.1016/j.jcis.2011.09.042 %T Extraordinarily water permeable sol-gel formed nanocomposite nanofibrous membranes %U https://doi.org/10.1016/j.jcis.2011.09.042 1 %X Electrospun nanofibrous membranes (ENMs) are considered as a state of the art in water filtration technology mainly owing to their high interconnected porosity and tunable pore size assumed to offer a very high permeability also selectivity. However, the extremely high surface area makes the ENMs prone to mechanical breakdown and lack of wettability lowering the filtration efficiency. Hence, any attempt to enhance both the mechanical properties and hydrophilicity of the ENMs is highly recommended.,In the current study, the structural and transport properties of polyethersulfone (PES) ENMs were modified through incorporation of titania (TiO2) nanoparticles via a sol-gel approach. Presence of titania precursor increased the conductivity of the electrospun solution thereby optimized the structural features of the electrospun mat in terms of formation of very thin beadless nanofibers, a higher porosity and smaller pore size. Moreover, a significant rise in mechanical properties, thermal stability and switching from a highly hydrophobic membrane to a superhydrophilic one occur simultaneously. The combination of a more optimum porosity, very high mechanical properties and hydrophilicity leads to a significantly higher water permeability in the TiO2/PES ENMs encouraging us to propose it as a water filtration membrane with longer life span and lower energy consumption. %0 journal article %@ 0376-7388 %A Fritsch, D.,Merten, P.,Heinrich, K.,Lazar, M.,Priske, M. %D 2012 %J Journal of Membrane Science %N %P 222-231 %R doi:10.1016/j.memsci.2012.02.008 %T High performance organic solvent nanofiltration membranes: Development and thorough testing of thin film composite membranes made of polymers of intrinsic microporosity (PIMs) %U https://doi.org/10.1016/j.memsci.2012.02.008 %X High free volume polymers are characterized by much higher permeability and diffusivity for gases and vapors than commodity polymers. Polymers of intrinsic microporosity (PIMs), an important member of this class of polymers, are only soluble in a few solvents. This gives reason to expect stability in many solvents and an application in organic solvent nanofiltration (OSN) may be feasible. Thin film composite membranes of PIM-1 and PIM copolymers were developed on a polyacrylonitrile (PAN) porous support. For control of swelling, a simple, technically realizable method of cross-linking was produced by blending the PIM with polyethyleneimine, coating to give thin film composites (TFCs) and thermally or chemically cross-linking the separation layer on the supporting membrane. The TFCs were tested in OSN with the solvents n-heptane, toluene, chloroform, tetrahydrofuran, and alcohols, and compared to similarly cross-linked poly(trimethylsilyl propyne) TFCs and state of the art industrial Starmem™ 240 membranes. Better retention, a steeper retention curve and much higher fluxes were detected for the newly developed PIM TFC membranes. %0 journal article %@ 1931-7573 %A Khan, M.M.,Filiz, V.,Bengtson, G.,Shishatskiy, S.,Rahman, M.M.,Abetz, V. %D 2012 %J Nanoscale Research Letters %N %P 504 %R doi:10.1186/1556-276X-7-504 %T Functionalized carbon nanotubes mixed matrix membranes of polymers of intrinsic microporosity for gas separation %U https://doi.org/10.1186/1556-276X-7-504 %X The present work reports on the gas transport behavior of mixed matrix membranes (MMM) which were prepared from multi-walled carbon nanotubes (MWCNTs) and dispersed within polymers of intrinsic microporosity (PIM)-1 matrix. The MWCNTs were chemically functionalized with poly(ethylene glycol) (PEG) for a better dispersion in the polymer matrix. MMM-incorporating functionalized MWCNTs (f-MWCNTs) were fabricated by dip-coating method using microporous polyacrylonitrile membrane as a support and were characterized for gas separation performance. Gas permeation measurements show that MMM incorporated with pristine or functionalized MWCNTs exhibited improved gas separation performance compared to pure PIM-1. The f-MWCNTs MMM show better performance in terms of permeance and selectivity in comparison to pristine MWCNTs. The gas permeances of the derived MMM are increased to approximately 50% without sacrificing the selectivity at 2 wt.% of f-MWCNTs' loading. The PEG groups on the MWCNTs have strong interaction with CO2 which increases the solubility of polar gas and limit the solubility of nonpolar gas, which is advantageous for CO2/N2 selectivity. The addition of f-MWCNTs inside the polymer matrix also improved the long-term gas transport stability of MMM in comparison with PIM-1. The high permeance, selectivity, and long term stability of the fabricated MMM suggest that the reported approach can be utilized in practical gas separation technology. %0 journal article %@ 1931-7573 %A Majeed, S.,Filiz, V.,Shishatskiy, S.,Wind, J.,Abetz, C.,Abetz, V. %D 2012 %J Nanoscale Research Letters %N %P 296 %R doi:10.1186/1556-276X-7-296 %T Pyrene-POSS nanohybrid as a dispersant for carbon nanotubes in solvents of various polarities: its synthesis and application in the preparation of a composite membrane %U https://doi.org/10.1186/1556-276X-7-296 %X In this study we report the preparation of nanohybrid dispersant molecules based on pyrene and polyhedral oligomeric silsesquioxanes for non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs). The prepared dispersant improves the dispersion of MWCNTs in organic solvents with very different polarities such as tetrahydrofuran, toluene, and n-hexane. The functionalized MWCNTs were used to introduce conductivity into polydimethylsiloxane membranes which can be used for electrostatic discharge applications. %0 journal article %@ 0032-3861 %A Michell, R.M.,Mueller, A.J.,Boschetti de Fierro, A.,Fierro, D.,Lison, V.,Raquez, J.-M.,Dubois, P. %D 2012 %J Polymer %N 25 %P 5657-5665 %R doi:10.1016/j.polymer.2012.10.021 %T Novel poly(ester-urethane)s based on polylactide: From reactive extrusion to crystallization and thermal properties %U https://doi.org/10.1016/j.polymer.2012.10.021 25 %X The synthesis of novel poly(ester-urethane)s (PEUs) based on polylactide was carried out. It was performed by a catalysed two-step reaction process, i.e., ring-opening polymerization (ROP) and chain extension reaction in bulk. For this purpose, α,ω-dihydroxyl PLA macrodiols were synthesized by catalysed ROP and employed as precursors that reacted in the melt with 4,4′-diisophenylmethane diisocyanate (MDI) and 4,4′-diaminodiphenylmethane (MDA) as coupling agent and chain extender, respectively. The PEUs were characterized by DSC, Polarized Light Optical Microscopy and X-ray techniques. The PEUs were generally characterized by higher cold crystallization temperature, lower melting temperature and slower cold crystallization kinetics as compared to the PLA precursors. The Avrami equation modelled the entire isothermal cold crystallization process. The synthesis variables that had the largest impact on the crystallization and thermal properties of the PEUs were the molecular weight of the PLA precursors and the [NCO]/[OHPLA + NH2] ratio, which could be readily tailored by the investigated reactive melt-processing. %0 conference lecture %@ %A Homaeigohar, S.,Disci-Zayed, D.,Dai, T.,Elbahri, M. %D 2012 %J Materials Science and Engineering, MSE 2012 %N %P %T Biofunctionalized nanofibrous membranes mimicking carnivorous plants %U %X %0 journal article %@ 0170-0839 %A Rangelov, S.,Simon, P.,Toncheva-Moncheva, N.,Dimitrov, P.,Gajewska, B.,Tsvetanov, C.B. %D 2012 %J Polymer Bulletin %N 8 %P 2175-2185 %R doi:10.1007/s00289-012-0724-z %T Nanosized colloidal particles from thermosensitive poly(methoxydiethyleneglycol methacrylate)s in aqueous media %U https://doi.org/10.1007/s00289-012-0724-z 8 %X The formation of well-defined colloidal particles (mesoglobules) from the thermosensitive polymer poly(methoxydiethyleneglycol methacrylate) was observed in dilute aqueous solutions (0.5–1.0 g/L) by turbidimetry and dynamic light scattering (DLS). DLS measurements were performed at 70 °C and showed a strong influence of polymer molecular weight: the hydrodynamic diameters of the mesoglobules increased from ca. 160 to 330 nm with a relatively small, i.e., from 6,400 to 14,000, increase in molecular weight. The addition of sodium dodecyl sulfate (SDS) at surfactant/polymer ratios (s/p, g/g) ranging from 0.3 to 0.5 practically inhibited the clouding of the solutions as the initial transmittance decreased by only 10–30%. Furthermore, a dramatic shift of the original cloud point values taken as a 10% decrease in transmittance, by approximately 20–60 °C was registered upon the surfactant addition. The presence of SDS resulted in size reduction by 52–90% as indicated by DLS. %0 journal article %@ 0947-8396 %A Hedayati, M.K.,Faupel, F.,Elbahri, M. %D 2012 %J Applied Physics A %N 4 %P 769-773 %R doi:10.1007/s00339-012-7344-1 %T Tunable broadband plasmonic perfect absorber at visible frequency %U https://doi.org/10.1007/s00339-012-7344-1 4 %X Metamaterials and plasmonics as a new pioneering field in photonics joins the features of photonics and electronics by coupling photons to conduction electrons of a metal as surface plasmons (SP). This concept has been implemented for a variety of applications including negative index of refraction, magnetism at visible frequency, cloaking devices amongst others. In the present work, we used plasmonic hybrid material in order to design and fabricate a broad-band perfect plasmonic metamaterial absorber in a stack of metal and Copper-PTFE (Polytetrafluoroethylene) nanocomposite showing an average absorbance of 97.5 % in the whole visible spectrum. Our experimental results showed that the absorption peak of the stacks can be tuned upon varying the thickness and type of the spacer layer due to the sensitivity of plasmon resonance to its environment. To the best of our knowledge, this is the first report of a plasmonic metamaterial absorber based on copper with absorption around 100 % in the entire visible and near-Infrared (NIR). %0 journal article %@ 1369-7021 %A Homaeigohar, S.,Elbahri, M. %D 2012 %J Materials Today %N 12 %P 591 %R doi:10.1016/S1369-7021(13)70015-4 %T Nano galaxy - A novel electrospun nanofibrous membrane that’s out of this world %U https://doi.org/10.1016/S1369-7021(13)70015-4 12 %X No abstract %0 journal article %@ 1383-5866 %A Homaeigohar, S.,Koll, J.,Lilleodden, E.T.,Elbahri, M. %D 2012 %J Separation and Purification Technology %N %P 456-463 %R doi:10.1016/j.seppur.2012.06.027 %T The solvent induced interfiber adhesion and its influence on the mechanical and filtration properties of polyethersulfone electrospun nanofibrous microfiltration membranes %U https://doi.org/10.1016/j.seppur.2012.06.027 %X Electrospun nanofibrous membranes (ENMs) as a novel class of energy saving membranes are under extensive investigation. This kind of membranes are highly porous and permeable however mechanically weak. In the current study, we benefited the residual solvent of the electrospun nanofibers to induce an interfiber adhesion through a thermal treatment. This approach was successful in enhancement of the mechanical properties of the electrospun nanofibrous membrane probed via tensile test and nanoindentation as a higher elastic modulus and compaction resistance, respectively. The mechanically stronger membrane possesses a higher resistance against tensile disintegration thereby a lower water flux at high feed pressures. Through a particle challenge test i.e. filtration of a TiO2 aqueous nanosuspension under an incremental feed pressure of 1-2 bar, we could also show that a mechanically resistant ENM can offer a more optimum filtration efficiency mainly due to its higher structural integration. %0 journal article %@ 0024-9297 %A Oss-Ronen, L.,Schmidt, J.,Abetz, V.,Radulescu, A.,Cohen, Y.,Talmon, Y. %D 2012 %J Macromolecules %N 24 %P 9631-9642 %R doi:10.1021/ma301611c %T Characterization of Block Copolymer Self-Assembly: From Solution to Nanoporous Membranes %U https://doi.org/10.1021/ma301611c 24 %X Self-assembly of isoporous membranes of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) involves many parameters: the block copolymer composition, the solvent and its interactions with the respective blocks, composition of the casting solution, solvent evaporation, and immersion into a water bath. We characterized the self-assembly of PS-b-P4VP in solution in nearly neutral or P4VP-selective solvent and on the surface of a cast film. We used a combination of room temperature (RT) and cryogenic high-resolution scanning electron microscopy (cryo-HR-SEM) to study copolymer micellization in dried films, in solution, and on the membrane surface during evaporation. The solutions, with and without addition of small water amounts, were investigated by cryogenic transmission electron microscopy (cryo-TEM) and small-angle neutron scattering (SANS). We have shown that the starting point for membrane formation is a microphase-separated copolymer solution with the P4VP within the micelle core. As water is introduced, this structure is preserved as long as the system is far from equilibrium. Closer to equilibrium the PS blocks form the micelles core. %0 journal article %@ 0032-3861 %A Du, B.,Handge, U.A.,Majeed, S.,Abetz, V. %D 2012 %J Polymer %N 24 %P 5491-5501 %R doi:10.1016/j.polymer.2012.09.047 %T Localization of functionalized MWCNT in SAN/PPE blends and their influence on rheological properties %U https://doi.org/10.1016/j.polymer.2012.09.047 24 %X In this work, the morphological and rheological properties of SAN/PPE blends filled with functionalized multi-walled carbon nanotubes (MWCNT) were investigated. Functionalized MWCNT with polystyrene (PS) were prepared by atom transfer radical polymerization (ATRP). Different molecular weights of grafted PS were achieved by varying the time of polymerization. MWCNT fillers were pre-mixed with SAN by solution casting. The degree of dispersion of MWCNT significantly depended on the miscibility between grafted PS and SAN. A “solid-like” behavior at low frequencies of linear viscoelastic oscillations was observed for SAN melts filled with 2.5 wt% MWCNT. The pre-mixed SAN/MWCNT composites were blended with PPE in the melt by means of a micro-compounder. In SAN/PPE blends, pristine MWCNT with poor dispersibility stayed in the pre-mixed SAN phase. The functionalized MWCNT tended to migrate from the pre-mixed SAN phase to the PPE phase. The extent of migration depended on the molecular weight of grafted polystyrene on the surface of MWCNT. The rheological results showed that MWCNT increase the dynamic moduli G′ and G″ as well as the complex viscosity of SAN/PPE blends. A higher molecular weight of grafted polystyrene effectively reduced the viscosity of PPE and thus led to a decrease of the viscosity of SAN/PPE blends filled with these functionalized MWCNT. %0 journal article %@ 1877-7058 %A Abetz, V.,Filiz, V.,Rangou, S.,Abetz, C.,Jung, A.,Buhr, K. %D 2012 %J Procedia Engineering %N %P 194-197 %R doi:10.1016/j.proeng.2012.08.355 %T Self–assembled Integral Asymmetric Block Copolymer Membranes: Structure Formation and Properties %U https://doi.org/10.1016/j.proeng.2012.08.355 %X No abstract %0 journal article %@ 1932-7447 %A Zillohu, A.U.,Abdelaziz, R.,Keshavarz Hedayati, M.,Emmler, T.,Homaeigohar, S.,Elbahri, M. %D 2012 %J The Journal of Physical Chemistry C %N 32 %P 17204-17209 %R doi:10.1021/jp3016358 %T Plasmon-Mediated Embedding of Nanoparticles in a Polymer Matrix: Nanocomposites Patterning, Writing, and Defect Healing %U https://doi.org/10.1021/jp3016358 32 %X Plasmonics, as an emerging field, aims to exploit the unique optical properties of metallic nanostructures to enable routing and active manipulation of light on the nanoscale. Plasmonic heating is a phenomenon, which is recently recognized for its potential in photothermal therapy. Here we show the first proof-of-concept experiment based on plasmonic heating for selective and precise embedding of nanoparticles in a polymeric matrix. We demonstrate a unique way for in situ fabrication of nanocomposites in different forms including patterning, writing, and defect healing in a controlled manner along with crystallinity control through light irradiation. %0 journal article %@ 1616-301X %A Elbahri, M.,Homaeigohar, S.,Abdelaziz, R.,Dai, T.,Khalil, R.,Zillohu, A.U. %D 2012 %J Advanced Functional Materials %N 22 %P 4771-4777 %R doi:10.1002/adfm.201200768 %T Smart Metal–Polymer Bionanocomposites as Omnidirectional Plasmonic Black Absorber Formed by Nanofluid Filtration %U https://doi.org/10.1002/adfm.201200768 22 %X The first smart plasmonic absorber based on metal-polymer bionanocomposites performing via conformational changes of the biological functional agent, i.e., a protein, is introduced. Such a progress is done through bridging the gaps between nanofluid filtration, plasmonics, and bioswitching. Initially, a biofunctionalized nanofibrous membrane is developed that could filter out metal nanoparticles (<100 nm) from an aqueous stream with a high separation efficiency (97%). This approach brings about a breakthrough in applicability of the macroporous nanofibrous membranes for rejection of suspended nanosolids and extends the application area beyond microfiltration (MF) to ultrafiltration (UF). This operative filtration in the next step leads to a novel synthesis route for plasmonic materials as formation of a smart free-standing metal–polymer bionanocomposite able to act as an omnidirectional black absorber. %0 journal article %@ 1533-4880 %A Xu, P.,Ji, X.,Abetz, V.,Jiang, S. %D 2011 %J Journal of Nanoscience and Nanotechnology %N 2 %P 1135-1140 %R doi:10.1166/jnn.2011.3077 %T Micropatterning of Ag and Au Nanoparticles by Microcontact Printing and Block Copolymer Micelles %U https://doi.org/10.1166/jnn.2011.3077 2 %X Micropatterns of gold and silver nanoparticles were successfully obtained by combining micro-contact printing and poly(2-vinylpyridine)-block-poly(cyclohexyl metharylate) (P2VP-b-PCHMA) diblock copolymer micelles with metal precursors. The metal ions were incorporated into poly(2-vinylpyridine) blocks and located into the core area of micelles. Then the metal-loaded micellar solutions were used as inks which were spin coated as thin layers onto polydimethylsiloxane stamps and transferred onto the substrates by stamping. Different morphologies of micellar aggregates were formed on the substrates depending on the stamp morphologies, and single layers of nanoparticles in the micropattern were obtained by the reducing process. %0 conference lecture (invited) %@ %A Elbahri, M. %D 2011 %J GDCh-Kolloquium %N %P %T Nanochemie: Aspekte und Trends %U %X %0 conference lecture %@ %A Hedayati, M.K.,Jamali, M.,Strunkus, T.,Zaporochentko, V.,Faupel, F.,Elbahri, M. %D 2011 %J 75. Jahrestagung der DPG und DPG Fruehjahrstagung %N %P %T New transparent conductive metal based on polymer composite %U %X %0 conference lecture %@ %A Homaeigohar, S.,Elbahri, M. %D 2011 %J International Congress on Membranes and Membrane Processes, ICOM 2011 %N %P %T Ceramic nanoparticles doped Polymeric nanofibrous membranes - An electrospun nanocomposite mat for water filtration %U %X %0 conference lecture %@ %A Khalil, R.M.A.,Abdelaziz, R.M.A.,Strunkus, T.,Faupel, F.,Elbahri, M. %D 2011 %J 75. Jahrestagung der DPG und DPG Fruehjahrstagung %N %P %T A study on nanocomposites made of a conducting polymer and metallic nanoparticles %U %X %0 conference lecture (invited) %@ %A Elbahri, M. %D 2011 %J Nanomanufacturing and Nanotribology, German-Chinese Symposium %N %P %T Nanochemistry: From Synthesis to Nanodevices and Bionanotechnology %U %X %0 journal article %@ 0014-3057 %A Rangou, S.,Shishatskiy, S.,Filiz, V.,Abetz, V. %D 2011 %J European Polymer Journal %N 4 %P 723-729 %R doi:10.1016/j.eurpolymj.2010.10.024 %T Poly(vinyl trimethylsilane) and block copolymers of vinyl trimethylsilane with isoprene: Anionic polymerization, morphology and gas transport properties %U https://doi.org/10.1016/j.eurpolymj.2010.10.024 4 %X Poly(vinyl trimethylsilane) (PVTMS) and block copolymers of vinyl trimethylsilane with isoprene were synthesized by anionic polymerization and characterized. The synthesized pure PVTMS has properties similar to a reference material produced about two decades ago and can be used for thin film composite membrane formation. Even at low isoprene content the block copolymers have improved film forming properties compared to the pure PVTMS. However, the presence of the isoprene units in the block copolymers leads to a decrease of the gas permeability but does not affect the selectivity of the membranes (α(O2/N2) = 3.9). %0 journal article %@ 1438-1656 %A Alburne, J.,Boschetti de Fierro, A.,Abetz, C.,Fierro, D.,Abetz, V. %D 2011 %J Advanced Engineering Materials %N 8 %P 803-810 %R doi:10.1002/adem.201000291 %T Block Copolymer Nanocomposites Based on Multiwall Carbon Nanotubes: Effect of the Functionalization of Multiwall Carbon Nanotubes on the Morphology of the Block Copolymer %U https://doi.org/10.1002/adem.201000291 8 %X Films based on a commercial block copolymer and multiwall carbon nanotubes (MWCNTs) were prepared by solution casting. The block copolymer has a star asymmetric chain architecture, with polystyrene chains of different lengths and a polybutadiene core. The block copolymer has a lamellar morphology. The MWCNT were grafted with polystyrene chains under atom transfer radical polymerization (ATRP) conditions. The nanocomposites were characterized by transmission electron microscopy (TEM) and simultaneous small angle X-ray scattering (SAXS)/strain–stress tests. The morphology of the nanocomposites is influenced by the polystyrene chain grafted from the MWCNT. In the case of the nanocomposite based on pristine MWCNT, most of the nanotubes intersect the lamellar domains of the block copolymer. With the increase of the molecular weight and the grafting chain density of the polystyrene anchored to the MWCNT, a favorable interaction between the polystyrene microdomain phases in the block copolymer and the MWCNT is observed. In the case where the MWCNT grafted with the relative highest molecular weight (20 kg·mol−1) and polystyrene grafted content (> 90 wt%), the MWCNT locally templates the lamellar morphology of the block copolymer. The effect on the block copolymer is analyzed based on the orientation of the morphology under an external deformation. %0 journal article %@ 1022-1352 %A Dai, T.,Miletic, N.,Loos, K.,Elbahri, M.,Abetz, V. %D 2011 %J Macromolecular Chemistry and Physics %N 4 %P 319-327 %R doi:10.1002/macp.201000536 %T Electrospinning of Poly[acrylonitrile-co-(glycidyl methacrylate)] Nanofibrous Mats for the Immobilization of Candida Antarctica Lipase B %U https://doi.org/10.1002/macp.201000536 4 %X PANGMA nanofibers and nanomats with fiber diameters of 200–300 nanometers were fabricated by electrospinning. Cal-B was covalently immobilized onto the PANGMA nanomats via three different immobilization routes. The properties of the Cal-B-immobilized PANGMA nanomats were assayed and compared with the free Cal-B. The observed Cal-B loading on these nanomats is up to ≈50mg·g−1, and their hydrolytic activity is up to ≈2500 nmol·min−1·mg−1, much higher than free enzyme powder and also slightly higher than Novozyme 435. Cal-B immobilized PANGMA nanomats have better reusability, thermal stability, and storage ability than free Cal-B. They retain over 50% of their initial activity after 15 cycles, over 65% after 10h heat incubation, and over 75% after 30 d storage. %0 journal article %@ 1359-8368 %A Loos, M.,Abetz, V.,Schulte, K. %D 2011 %J Composites / B %N 3 %P 414-420 %R doi:10.1016/j.compositesb.2010.12.008 %T In situ synthesis of polyoxadiazoles (POD) and carbon black (CB) as an approach to POD/CB nanocomposites %U https://doi.org/10.1016/j.compositesb.2010.12.008 3 %X Pristine carbon black was oxidized with poly(phosphoric acid) to produce carboxyl groups. The carboxyl groups were consecutively treated with hydrazine sulfate to introduce arylcarbonyl and CONHNH2 groups. The groups on the CB surface were reacted with dicarboxylic acid to anchor the growing of polyoxadiazole chains. The properties of the bulk POD/CB composites were characterized by elemental analysis (EA), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA). The final composites were processed in films using a solution method aided by the use of a mini-calendar for final high shear mixing. Transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic mechanical thermal analysis (DMTA) and tensile tests were used to systemically characterize the high performance composite films. The POD composites with high molecular weight (in the order of magnitude of 105 g/mol) were soluble in polar aprotic solvents and stable at temperatures as high as 465 °C. The incorporation of the CB enhanced the overall mechanical properties of the composites at low CB content due to the presence of strong interfacial interaction between the polymer matrix and the filler. %0 journal article %@ 0959-8103 %A Loos, M.,Abetz, V.,Schulte, K. %D 2011 %J Polymer International %N 3 %P 517-528 %R doi:10.1002/pi.2983 %T Fast and highly efficient one-pot synthesis of polyoxadiazole/carbon nanotube nanocomposites in mild acid %U https://doi.org/10.1002/pi.2983 3 %X Sulfonated poly(4,4′-diphenylether-1,3,4-oxadiazole) (POD) composites have been successfully prepared through solution polycondensation of 4,4′-diphenylether dicarboxylic acid and hydrazine sulfate. The reactions were performed in the presence of various types of pristine carbon nanotubes, i.e. single-, double- and multi-walled carbon nanotubes, using mild poly(phosphoric acid) as a condensing agent. The POD composites with high molecular weight (of the order of 105 g mol−1) were highly soluble in polar aprotic solvents and thermally stable at temperatures as high as 475 °C. The synthesis method used guaranteed an improved interaction between filler and matrix, thus allowing an enhanced load transfer. The overall performance of the composites was enhanced due to a synergistic reinforcement effect. The nanocomposites exhibited an increase of +33% in storage modulus, +56% in tensile strength and +245% in tensile energy to break. %0 journal article %@ 1022-1352 %A Fritsch, D.,Bengtson, G.,Carta, M.,McKeown, N.B. %D 2011 %J Macromolecular Chemistry and Physics %N 11 %P 1137-1146 %R doi:10.1002/macp.201100089 %T Synthesis and Gas Permeation Properties of Spirobischromane-Based Polymers of Intrinsic Microporosity %U https://doi.org/10.1002/macp.201100089 11 %X Polymers of intrinsic microporosity (PIMs) possess molecular structures composed of fused rings with linear units linked together by a site of contortion so that the macromolecular structure is both rigid and highly non-linear. For PIM-1, which has previously demonstrated encouraging gas,permeability data, the site of contortion is provided by the monomer 5,5',6,6'-tetrahydroxy-3,3,3',3' tetramethyl-1,1'-spirobisindane. Here we describe the synthesis and properties of a PIM derived from the structurally related 6,6’,7,7’-tetrahydroxy-4,4,4’,4’-tetramethyl-2,2’-spirobischromane and copolymers prepared from combination of this monomer with other PIM-forming biscatechol,monomers, including the highly rigid monomer 9,10-dimethyl-9,10-ethano-9,10-dihydro-2,3,6,7-,tetrahydroxyanthracene. Generally the polymers display good solubility in organic solvents and have,high average molecular masses (Mw) in the range 80000-200000 g/mol and, therefore, are able to form,robust, solvent-cast films. Gas permeability and selectivity for He, H2, N2, O2, CO2 and CH4 were,measured for the polymers and compared to the values previously obtained for PIM-1. The,spirobischromane-based polymers demonstrate enhanced selectivity for a number of gas pairs but with,significantly lower values for permeability. The solubility coefficient for CO2 of two of the copolymers exceed even that of PIM-1, which previously demonstrated the highest value for a membraneforming polymer. Therefore, these polymers might be useful for gas or vapor separations relying on solubility selectivity. %0 journal article %@ 1616-301X %A Ungar, G.,Tschierske, C.,Abetz, V.,Holyst, R.,Bates, M.A.,Lui, F.,Prehm, M.,Kieffer, R.,Zeng, X.,Walker, M.,Glettner, B.,Zywocinski, A. %D 2011 %J Advanced Functional Materials %N 7 %P 1296-1323 %R doi:10.1002/adfm.201002091 %T Self-Assembly at Different Length Scales: Polyphilic Star-Branched Liquid Crystals and Miktoarm Star Copolymers %U https://doi.org/10.1002/adfm.201002091 7 %X The diversity of phase morphologies observed recently in star-branched liquid-crystalline and polymeric compounds containing at least three immiscible segments is reviewed. Bolaamphiphiles and facial amphiphiles with rodlike aromatic cores, two end-groups, and one (T-shape) or two (X-shape) chains attached laterally to the core, form numerous honeycomblike liquid-crystal phases, as well as a variety of novel lamellar and 3D-ordered mesophases. Molecular self-organization is described in bulk phases and in thin films on solid and liquid surfaces, as well as in Langmuir–Blodgett films. The remarkably reversible formation of mono- and trilayer films is highlighted. In the bulk, T-shaped “rod–coil” molecules without appended end-groups form predominantly lamellar phases if the core is a straight rod, but the bent-core variety forms hexagonal honeycombs. Furthermore, self-assembly of “Janus”-type molecules, is discussed. Also covered is the diversity of morphologies observed in miktoarm star terpolymers, i.e., polymers with three different and incompatible arms of well defined lengths. Similarities and differences are highlighted between the liquid-crystal morphologies on the 3–15 nm scale and the polymer morphologies on the scale of 10–100 nm. A separate section is dedicated to computer simulations of such systems, particularly those using dissipative particle and molecular dynamics. Of special interest are the recently synthesised X-shaped tetraphilic molecules, where two different and incompatible side-chains are attached at opposite sides of the rodlike core. The tendency for their phase separation produces liquid-crystal honeycombs with cells of different compositions that can be represented as a plane paved with different colored tiles. The independent variation of chain length and “color” creates the potential for developing a considerable range of complex new 2D and 3D soft nanostructures. Analogous X-shaped rod–coil compounds with unequal side groups are also of considerable interest, forming tubular lyotropic structures capable of confining strings of guest molecules. %0 conference lecture %@ %A Elbahri, M.,Homaeigohar, S.,Dai, T.,Khalil, R.,Abdelaziz, R. %D 2011 %J International Congress on Membranes and Membrane Processes, ICOM 2011 %N %P %T Nanofluid Filtration using Electrospun Nanofibers %U %X %0 journal article %@ 0935-9648 %A Elbahri, M.,Hedayati, M.K.,Chakravadhanula, V.S.K.,Jamali, M.,Strunkus, T.,Zaporojtchenko, V.,Faupel, F. %D 2011 %J Advanced Materials %N 17 %P 1993-1997 %R doi:10.1002/adma.201003811 %T An Omnidirectional Transparent Conducting-Metal-Based Plasmonic Nanocomposite %U https://doi.org/10.1002/adma.201003811 17 %X A transparent conducting metal (TCM) composed of a stack of a gold film and silver/polymer nanocomposite fabricated by sputtering onto a glass substrate is presented. The plasmonic metamaterial shows an omnidirectional optical transmission up to 80% in the visible spectrum, which is comparable to that of ITO, and the electrical conductivity is one order of magnitude higher than that of ITO. %0 conference lecture (invited) %@ %A Elbahri, M. %D 2011 %J 5. Fachtagung mit Ausstellung:Transparent leitfaehige Schichten (TCO) %N %P %T Plasmonic nanocomposites %U %X %0 journal article %@ 0935-9648 %A Hedayati, M.K.,Javaherirahim, M.,Mozooni, B.,Abdelaziz, R.,Tavassolizadeh, A.,Chakravadhanula, V.S.K.,Zaporojtchenko, V.,Strunkus, T.,Faupel, F.,Elbahri, M. %D 2011 %J Advanced Materials %N 45 %P 5410-5414 %R doi:10.1002/adma.201102646 %T Design of a Perfect Black Absorber at Visible Frequencies Using Plasmonic Metamaterials %U https://doi.org/10.1002/adma.201102646 45 %X The design and fabrication of a plasmonic black absorber with almost 100% absorbance spanning a broad range of frequencies from ultraviolet (UV) to the near infrared (NIR) is demonstrated. The perfect plasmonic absorber is achieved by a combination of a metal film with suitable metal/dielectric nanocomposites. Our fabrication technique is simple, versatile, cost-effective, and compatible with current industrial methods for solar absorber production. %0 journal article %@ 0263-8762 %A Stuenkel, S.,Drescher, A.,Wind, J.,Brinkmann, T.,Repke, J.-U.,Wozny, G. %D 2011 %J Chemical Engineering Research and Design : CERD %N 8 %P 1261-1270 %R doi:10.1016/j.cherd.2011.02.024 %T Carbon dioxide capture for the oxidative coupling of methane process – A case study in mini-plant scale %U https://doi.org/10.1016/j.cherd.2011.02.024 8 %X The oxidative coupling of methane (OCM) to ethylene is a promising alternative for the oil based industry. In this process, beside the valuable product ethylene, unwanted by-products like CO2 are produced. Hence, the gas stream has to be refined further. The process is not applied in the industry yet, because of high separation costs. This article focuses particular on the CO2 purification of the OCM product stream. Therefore a case study was done for a design task of 90% CO2 capture from 25 vol% in the OCM product gas with an operation pressure of 32 × 105 Pa. Within the article is shown, how to resolve the lack of high separation cost for the purification and the development of an integrated, energy efficient CO2 capture process for the OCM refinery is described. Therefore a state of the art chemical absorption process using monoethanolamine (MEA) was developed and optimized for the base case. Therefore Aspen Plus® with the build-in rate based model for the mass transfer with an electrolyte NRTL – approach and chemical equilibrium reactions for the water–MEA–CO2 system as well as kinetic reactions based on the MEA-REA package was applied. In order to improve the energetic process performance, gas permeation with dense membranes was studied as process alternative. For this purpose a membrane unit was developed in Aspen Custom Modeler® (ACM). The solution-diffusion model with the free-volume-theory for gas permeation including Joule–Thomson effect as well as concentration polarization (Stünkel et al., 2009) was applied successfully. Furthermore several selective materials for a composite membrane with experimentally determined parameters were studied by this model and it was found, that a matrimide membrane provides the best selectivity performance for the OCM CO2 capture. Based on this material a membrane module was installed to form a hybrid separation process in combination with the amine based absorption process. The comparison of the state of the art process with the novel hybrid separation process shows an energy saving of more than 40% for the OCM CO2 capture. In the experimental study the stand alone performance of each unit, as well as the performance of the hybrid process were studied and the results are presented in this article. %0 journal article %@ 1533-4880 %A Xu, P.,Ji, X.,Abetz, V.,Jiang, S. %D 2011 %J Journal of Nanoscience and Nanotechnology %N 8 %P 6973-6978 %R doi:10.1166/jnn.2011.4211 %T Uniformly Gold Nanoparticles Derived from P2VP-b-PCHMA Block Copolymer Templates with Different Reduction Methods %U https://doi.org/10.1166/jnn.2011.4211 8 %X The micellization of poly(2-vinylpyridine)-block-poly(cyclohexyl methacrylate) (P2VP-b-PCHMA) in THF can be induced by the complexation between the P2VP blocks and HAuCl4, forming composite polymeric micelles with PCHMA being the shell and P2VP/HAuCl4 complex being the core. In order to obtain regular arrays of gold nanoparticles (Au NPs), monolayer of HAuCl4-loaded surface micelles have been produced by spin-coating the micellar solution, and Au NPs in different size have been obtained by oxygen plasma with different reduction processes. In addition, pyrole (PY) has been used as an efficient reducing agent to fabricate dispersed Au NPs within micellar structure in a short reducing time, resulting in a raspberry-like morphology of the Au-polymer composites. With the addition of annealing processes or longer reducing time (one month), different shapes of Au NPs have been observed in the cast films. Furthermore, core-shell nanostructures of gold-polypyrole (Au-PPY) have also been observed by employing vapor phase polymerization of PY onto HAuCl4-loaded polymeric solution-cast films. %0 journal article %@ 0935-9648 %A Jamali, M.,Hedayati, M.K.,Mozooni, B.,Javaheriahim, M.,Abdelaziz, R.,Zillohu, A.U.,Elbahri, M. %D 2011 %J Advanced Materials %N 37 %P 4243-4247 %R doi:10.1002/adma.201102353 %T Photoresponsive Transparent Conductive Metal with a Photobleaching Nose %U https://doi.org/10.1002/adma.201102353 37 %X A photoswitchable, transparent, and highly conducting device that functions via nanophotonic interaction of a metal film coated with spirophenanthrooxazine (SPO) molecules embedded in a polymeric matrix and fabricated through spin coating is demonstrated. The device possesses additional novel functionality as a photobleaching gas sensor. %0 journal article %@ 0376-7388 %A Fierro, D.,Scharnagl, N.,Emmler, T.,Boschetti de Fierro, A.,Abetz, V. %D 2011 %J Journal of Membrane Science %N 1-2 %P 63-71 %R doi:10.1016/j.memsci.2011.09.006 %T Experimental determination of self-diffusivities through a polymer network for single components in a mixture %U https://doi.org/10.1016/j.memsci.2011.09.006 1-2 %X Diffusion models such as Vrentas & Duda diffusion theory and Wesselingh & Bollen multicomponent diffusion model have been used together with estimated tracer diffusion coefficients in order to provide a predictive method to calculate thermodynamic diffusion coefficients needed for transport simulation in polymer membrane processes. PFG-NMR measurements were carried out in order to estimate the tracer diffusion coefficients for solvent–solvent–polymer systems on free-standing crosslinked polymer films. The use of experimentally determined diffusivities for a set of finite solvent-solvent-polymer concentrations as well as of plausible assumptions in nanofiltration allows the estimation of the unclear parameters presented in the diffusion theories with the subsequent predictability for those systems. %0 journal article %@ 0360-3199 %A Awasthi, K.,Stamm, M.,Abetz, V.,Vijay, Y.K. %D 2011 %J International Journal of Hydrogen Energy %N 15 %P 9374-9381 %R doi:10.1016/j.ijhydene.2011.04.200 %T Large area Cl 9+ irradiated PET membranes for hydrogen separation %U https://doi.org/10.1016/j.ijhydene.2011.04.200 15 %X In the present case, Polyethylene terephthalate (PET) membranes of thickness 25 μm were irradiated by 100 MeV Cl9+ ion beam with ion fluence of 107 ions/cm2. These membranes were etched in 6N NaOH at 60 °C at different etching times to generate pores. The permeabilities of nitrogen, oxygen, methane, carbon dioxide as well as hydrogen were measured for etched membranes at various etching times. The permeability of gases was found to increase with etching time and a rapid increase was noticed after a critical etching time when the etched tracks meet at their vertexes. The selectivity of hydrogen gas over other gases was also observed. %0 journal article %@ 1438-1656 %A Kaysser, W.,Esslinger, J.,Abetz, V.,Huber, N.,Kainer, K.U.,Klassen, T.,Pyczak, F.,Schreyer, A.,Staron, P. %D 2011 %J Advanced Engineering Materials %N 8 %P 637-657 %R doi:10.1002/adem.201100150 %T Research with Neutron and Synchrotron Radiation on Aerospace and Automotive Materials and Components %U https://doi.org/10.1002/adem.201100150 8 %X Characterization with neutrons and synchrotron radiation has yielded essential contributions to the research and development of automotive and aerospace materials, processing methods, and components. This review mainly emphasises developments related to commercial passenger airplanes and light-duty cars. Improved and partly new materials for the reduction of airframe weight and joining by laser-beam welding and friction stir welding are ongoing areas of assessment. Chemical reactions, microstructure development, and residual stresses are frequently measured. Polymers and polymer matrix composites often require special experimental techniques. The thrust-to-weight ratio of aero-engines is increasing due to the improved design of components and the use of innovative materials. Investigations on superalloys, γ-TiAl, and thermal barrier coatings are described in some detail. A discussion of the use of neutron and synchrotron diffraction in automotive applications covers the analysis of surface effects with respect to lubricants and wear, as well as the investigation of microstructure development, deformation, and fatigue behavior of materials, welds and components. Special steels, Al and Mg alloys are discussed and residual stresses in automotive components such as gears or crankshafts are described. Applications of characterization methods on membranes for polymeric membrane fuel cells and on nanocrystalline metal hydrides for hydrogen storage are shown. The degradation of railway tracks after long-term use is taken as an example for the application of synchrotron methods to transport systems beyond the commercial aircraft and light duty passenger car. %0 journal article %@ 1359-7345 %A Short, R.,Carta, M.,Grazia Bezzu, C.,Fritsch, D.,Kariuki, B.M.,McKeown, N.B. %D 2011 %J Chemical Communications : ChemComm %N 24 %P 6822-6824 %R doi:10.1039/c1cc11717c %T Hexaphenylbenzene-based polymers of intrinsic microporosity %U https://doi.org/10.1039/c1cc11717c 24 %X Microporous polymers derived from the 1,2- and 1,4-regioisomers of di(3′,4′-dihydroxyphenyl)tetraphenylbenzene have very different properties with the former being composed predominantly of cyclic oligomers whereas the latter is of high molar mass suitable for the formation of robust solvent-cast films of high gas permeability. %0 journal article %@ 1022-1352 %A Loos, M.,Abetz, V.,Schulte, K. %D 2011 %J Macromolecular Chemistry and Physics %N 12 %P 1236-1244 %R doi:10.1002/macp.201100048 %T A Highly Efficient One-Pot Method for the Synthesis of Carbon Black/Poly(4,4′-Diphenylether-1,3,4-Oxadiazoles) Composites %U https://doi.org/10.1002/macp.201100048 12 %X A series of polyoxadiazoles (PODs) based composites containing carbon black (CB) are prepared through a fast polycondensation reaction of hydrazine sulfate and dicarboxylic acid monomers using poly(phosphoric acid) (PPA) as reaction medium. In order to achieve a homogeneous dispersion of CB, a predispersion step is applied to the CB prior to the synthesis. The moderate acidic nature and high viscosity of the PPA medium promote the oxidation of the CB and suppress reaggregation after dispersion. The carboxylic groups generated on the surface of the CB effectively anchored the growing of POD chains, improving the interfacial interaction between the CB and the surrounding matrix. An increase of 22% in storage modulus at 100 °C is observed. The tensile strength increases up to 48% with the CB addition and the elongation at break increases up to 118% at a low concentration of CB (0.5 wt.-%). The resultant CB/POD composites, which can be cast as dense films, are soluble in several polar aprotic solvents and their POD matrix have molecular weights in the range of 105 g·mol−1. The high-performance, high-temperature light-weight materials obtained are thermally stable at temperatures as high as 450°C. %0 journal article %@ 0266-3538 %A Lin, D.,Boschetti de Fierro, A.,Alexandre, M.,Abetz, C.,Boettcher, H.,Abetz, V.,Urbanczyk, L.,Jerome, C.,Han, C.C. %D 2011 %J Composites Science and Technology %N 16 %P 1893-1897 %R doi:10.1016/j.compscitech.2011.09.003 %T Morphology and mechanical properties of bisphenol A polycarbonate/poly (styrene-co-acrylonitrile) blends based clay nanocomposites %U https://doi.org/10.1016/j.compscitech.2011.09.003 16 %X Two organic modified clays (Cloisite®30B (CL30B) and PCL /Cloisite®30B masterbatch (MB30B)) were used to improve the mechanical properties of polycarbonate (PC)/poly (styrene-co-acrylonitrile) (SAN) blends. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements of the melt blended nanocomposites revealed that partially exfoliated and partially degraded structure was obtained and the clay platelets were located mostly in the SAN phase and at the two-phase boundary. Dispersion of the clay platelets is better when MB30B were used. The mechanical properties of the clays filled nanocomposites vary accordingly and when MB30B is used better mechanical properties can be achieved. Tensile strength increases 41% at maximum as the CL30B loading is 5wt%, while elongation at break decreases dramatically. Impact strength can be improved up to 430% compared to the pure blend when 1wt% MB30B was used. %0 journal article %@ 0254-0584 %A Xu, P.,Ji, X.,Yang, H.,Qi, J.,Zheng, W.,Abetz, V.,Jiang, S.,Shen, J. %D 2010 %J Materials Chemistry and Physics %N 1-2 %P 249-253 %R doi:10.1016/j.matchemphys.2009.08.062 %T Controllable fabrication of carbon nanotubes on catalysts derived from PS-b-P2VP block copolymer template and in situ synthesis of carbon nanotubes/Au nanoparticles composite materials %U https://doi.org/10.1016/j.matchemphys.2009.08.062 1-2 %X Highly ordered iron oxide nanoparticles with controlled size and spacing over a large surface area were prepared with polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) diblock copolymer template, the obtained nanoparticles could be used as catalysts for CNTs growth in a plasma-enhanced chemical vapor deposition (PECVD) system. This route offers the capability of controlling the density of CNTs on the substrate by altering the growing time, and aligned CNTs grew vertically onto the substrates with a pre-coating of aluminium oxide (Al2O3) layer. In addition, Au nanoparticles were successfully attached to the sidewall of deposited CNTs through in situ synthetic method. %0 journal article %@ 1533-4880 %A Xu, P.,Ji, X.,Qi, J.,Yang, H.,Zheng, W.,Abetz, V.,Jiang, S.,Shen, J. %D 2010 %J Journal of Nanoscience and Nanotechnology %N 1 %P 508-513 %R doi:10.1166/jnn.2010.1587 %T Patterned Carbon Nanotubes Fabricated by the Combination of Microcontact Printing and DiblockCopolymer Micelles %U https://doi.org/10.1166/jnn.2010.1587 1 %X A convenient approach to synthesize patterned carbon nanotubes (CNTs) of three morphologies on printed substrates by combination of microcontact printing (CP) and a plasma-enhanced chemical vapor deposition (PECVD) process is presented. Micelles of polystyrene-block-poly-(2-vinylpyridine),(PS-b-P2VP) in toluene were used as nanoreactors to fabricate FeCl3 in the core domains, and the complex solution was used as an ink to print films with polydimethylsiloxane (PDMS) stamps, different morphologies (porous, dots and stripes patterns) of the FeCl3-loaded micellar films were left onto silicon substrates after printed. After removing the polymer by thermal decomposition, the left iron oxide cluster arrays on the substrate were used as catalysts for the growth of CNTs by the process of PECVD, where the CNTs uniformly distributed on the substrates according to the morphologies of patterned catalysts arrays. %0 journal article %@ 0887-6266 %A Albuerne, J.,Boschetti de Fierro, A.,Abetz, V. %D 2010 %J Journal of Polymer Science B %N 10 %P 1035-1046 %R doi:10.1002/polb.21992 %T Modification of multiwall carbon nanotubes by grafting from controlled polymerization of styrene: Effect of the characteristics of the nanotubes %U https://doi.org/10.1002/polb.21992 10 %X Linear polystyrene chains were grown from the convex surface of two commercially available multiwall carbon nanotubes (MWCNTs) with similar diameter but different lengths. The MWCNTs were supplied from Bayer Material Science® (purity >95%, external diameter = 13–16 nm, length = 1–10 μm, denoted MWCNTBMS95) and FutureCarbon GmbH (purity >99%, external diameter = 15 nm, length = 5–50 μm, denoted MWCNTFC99). The MWCNTs were oxidized with nitric acid, consecutively reacted with thionyl chloride, glycol or poly(ethylene glycol), 2-bromo-2-methylpropionyl bromide and finally with styrene under atom transfer radical polymerization (ATRP) conditions. The content of polystyrene grafted from the surface of the MWCNTs can be controlled by adjusting the molecular weight of the poly(ethylene glycol), the initiator concentration and the monomer to carbon nanotube weight ratio. Under comparable experimental conditions, a higher amount of polystyrene is grafted from the MWCNTBMS95 than from MWCNTFC99. The difference in dimensions and the state of aggregation of the carbon nanotubes influence the grafting from polymerization reactions, where relative shorter and tightly aggregated carbon nanotubes promote higher polymerizations yields than longer and less aggregated carbon nanotubes. The increase of the viscosity of the carbon nanotube dispersion decreases the polymer grafting content. %0 conference lecture %@ %A Homaeiggohar, S.,Elbahri, M.,Ebert, K.,Lilleodden, E.,Abetz, V. %D 2010 %J International Conference on Electrospinning %N %P %T Filtration potential and mechanical performance of an electrospun nanofibrous composite membrane used for liquid filtration %U %X %0 conference poster %@ %A Dai, T.,Ebert, K.,Abetz, V.,Elbahri, M.,Miletic, N.,Loos, K.,Plenio, H. %D 2010 %J International Conference on Electrospinning, ElectroSpin 2010 %N %P %T Fabricating novel solvent-resistant nanofibers for catalytic application %U %X %0 journal article %@ 0926-3373 %A Kopinke, F.-D.,Angeles-Wedler, D.,Fritsch, D.,Mackenzie, K. %D 2010 %J Applied Catalysis B %N 3-4 %P 323-328 %R doi:10.1016/j.apcatb.2010.02.028 %T Pd-Catalyzed Hydrodechlorination of Chlorinated Aromatics in Contaminated Waters - Effects of Surfactants, Organic Matter and Catalyst Protection by Silicone Coating %U https://doi.org/10.1016/j.apcatb.2010.02.028 3-4 %X Many chlorinated aromatic and aliphatic hydrocarbons dissolved in water can be rapidly and selectively hydrodechlorinated by means of Pd catalysts. However, if they appear in a complex water matrix, as is common for wastewater treatment or after soil extraction, the protection of the Pd sites against catalyst poisons may become the key step for applicability of this reaction. In the present study, Pd/Al2O3 was tested as hydrodechlorination (HDC) catalyst in various soil-washing effluents. As probe compounds 3-chlorobiphenyl (3-CBP), monochlorobenzene (MCB) and trichloroethene (TCE) were chosen. Specific catalyst activities up to APd = 200 L g−1 min−1 were measured in clean water. The influence of surfactants and co-solvents was studied. In addition, soil slurry supernatant was employed as reaction medium to appraise the influence of soil co-extractants (dissolved organic matter, DOM) on the dechlorination reaction. Results show that commercially available surfactants such as Tween 80, Triton X-100, SDBS, and CTMAOH as well as methanol as co-solvent with concentrations up to 20 vol% did not strongly affect the catalyst activity. However, the catalyst performance was heavily decreased in the presence of a soil slurry supernatant (40 mg L−1 DOM). Hydrophobic coating of the catalyst by silicone polymers was successful in protecting the Pd sites against ionic catalyst poisons such as DOM and bisulphite for at least 24 h. %0 journal article %@ 0016-3538 %A Lademann, B.,Simon, P.F.W. %D 2010 %J GIT-Laborfachzeitschrift %N 2 %P 102-105 %T Copolymere in der GPC - Bestimmung der Zusammensetzung %U 2 %X Durch die Verwendung zweier unterschiedlicher Konzentrationsdetektoren (z. B. UV- und Brechungsindex-Detektoren) in der Gelpermeationschromatographie kann die Zusammensetzung eines Diblockcopolymeren direkt aus den Elugrammen bestimmt werden. Hierzu ist eine Kalibration beider Detektoren mit entsprechenden Homopolymeren notwendig. Weiterhin erlaubt dieses Vorgehen die Quantifizierung von Precursorresten. %0 journal article %@ 0024-9297 %A Erukhimovich, I.Y.,Belousov, M.V.,Govorun, E.N.,Abetz, V.,Tamm, M.V. %D 2010 %J Macromolecules %N 7 %P 3465-3478 %R doi:10.1021/ma9023735 %T Non-Centrosymmetric Lamellar Structures in the Associating Blends of Tri- and Diblock Copolymers %U https://doi.org/10.1021/ma9023735 7 %X We consider lamellar morphologies in the mixtures of AC diblock and ABC triblock copolymers and show that a proper functionalization of the end blocks of the triblock and diblock copolymer chains by donor and acceptor functional groups, respectively, could result in occurrence of the thermodynamically stable noncentrosymmetric lamellar structures in such mixtures. Depending on the chemical nature of the donor-acceptor bond (i.e., the values of the effective entropy Sbond and energy E per one bond), the typical phase diagrams could contain the upper and lower triple points where the pure diblock, pure triblock and noncentrosymmetric lamellae of a finite composition coexist. With increase of the association strength the triple points merge and the noncentrosymmetric lamellae become thermodynamically favorable at all temperatures. The boundary on the (Sbond ,E)-plane, which separates the regions corresponding to different types of the phase behavior, is found. The influence of the architecture of the system and the chemical nature of the donor-acceptor bond on the stability of the noncentrosymmetric lamellae is analyzed and typical phase diagrams are presented. %0 journal article %@ 1022-1336 %A Munirasu, S.,Albuerne, J.,Boschetti de Fierro, A.,Abetz, V. %D 2010 %J Macromolecular Rapid Communications %N 6 %P 574-579 %R doi:10.1002/marc.200900751 %T Functionalization of Carbon Materials using Diels-Alder Reaction %U https://doi.org/10.1002/marc.200900751 6 %X A simple and efficient Diels-Alder (DA) reaction on carbon material has been demonstrated. The present work involves single and multiwall carbon nanotubes (CNTs), as well as Herringbone carbon nanofiber. The CNTs show a dual nature of reactivity in DA reaction, i.e., they behave both as dienophile and diene with furfuryl groups and maleic anhydride derivatives, respectively. Various functional groups, including alcohol, amine, epoxy, carboxylic and ester, have been introduced on the carbon materials. The results suggest that the reactivity of CNT in DA reaction may resemble the chemistry of small molecules. %0 journal article %@ 0024-9297 %A Emmler, T.,Heinrich, K.,Fritsch, D.,Budd, P.M.,Chaukura, N.,Ehlers, D.,Raetzke, K.,Faupel, F. %D 2010 %J Macromolecules %N 14 %P 6075-6084 %R doi:10.1021/ma1008786 %T Free Volume Investigation of Polymers of Intrinsic Microporosity (PIMs): PIM-1 and PIM1 Copolymers Incorporating Ethanoanthracene Units %U https://doi.org/10.1021/ma1008786 14 %X High free volume, film-forming copolymers were prepared in which a proportion of the spiro-units of PIM-1 were replaced with units derived from 9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene-2,3,6,7-tetrol (CO1). A full investigation of free volume, utilizing N2 sorption, positron annihilation lifetime spectroscopy (PALS), Xe sorption and 129Xe NMR spectroscopy, was undertaken for copolymer PIM1-CO1-40 (spiro-units:CO1 = 60:40) and a comparison is made with PIM-1. All techniques indicate that the copolymer, like PIM-1, possesses free volume holes or pores on the nanometre length scale (i.e., microporosity as defined by IUPAC). For the batch of PIM-1 studied here, the sample as received showed anomalous N2 sorption, Xe sorption and 129Xe NMR behavior that could be interpreted in terms of reduced porosity in the size range 0.6−0.7 nm, as compared to the copolymer. The anomalous behavior was eliminated on conditioning or relaxation of the polymer, e.g., by Xe sorption at 100 °C and 3 bar. PALS for both PIM1-CO1-40 and PIM-1 indicates a maximum in the average free volume hole size, and in the width of the distribution of hole sizes, on increasing temperature. This maximum appears to be a feature of high free volume polymers and may be related to the onset of localized oscillations of backbone moieties. %0 journal article %@ 1022-1352 %A Garaleh, M.,Yashiro, T.,Kricheldorf, H.R.,Simon, P.,Chatti, S. %D 2010 %J Macromolecular Chemistry and Physics %N 11 %P 1206-1214 %R doi:10.1002/macp.200900656 %T (Co-)Polyesters Derived from Isosorbide and 1,4-Cyclohexane Dicarboxylic Acid and Succinic Acid %U https://doi.org/10.1002/macp.200900656 11 %X The homopolyester of isosorbide and cis–trans 1,4-cyclohexane dicarboxylic acid (CHDA) was prepared by three different methods, but only polycondensation of isosorbide and CHDA dichloride yielded a satisfactory molecular weight (corrected equation image  = 11 000 Da). For the best sample the MALDI-TOF mass spectrum revealed a high content of cycles. The homopolyester of CHDA and isomannide or isoidide was prepared analogously. For the homopolyesters of CHDA high glass transition temperatures were found (Tg = 146  °C for isosorbide, 133 °C for isomannide, and 115 °C for isoidide), whereas the polyester of isosorbide and succinic acid (SuA) has a Tg around 77 °C. Copolyester of isosorbide and various molar ratios of CHDA and SuA were prepared by two different methods, but only rather low molecular weights were obtained. SEC measurements with and without “universal calibration” revealed that the normal calibration with polystyrene overestimates the real molecular weights by 30–45%. %0 journal article %@ 1022-1336 %A Miletic, N.,Abetz, V.,Ebert, K.,Loos, K. %D 2010 %J Macromolecular Rapid Communications %N 1 %P 71-74 %R doi:10.1002/marc.200900497 %T Immobilization of Candida antarctica lipase B on Polystyrene Nanoparticles %U https://doi.org/10.1002/marc.200900497 1 %X Polystyrene (PS) nanoparticles were prepared via a nanoprecipitation process. The influence of the pH of the buffer solution used during the immobilization process on the loading of Candida antarctica lipase B (Cal-B) and on the hydrolytic activity (hydrolysis of p-nitrophenyl acetate) of the immobilized Cal-B was studied. The pH of the buffer solution has no influence on enzyme loading, while immobilized enzyme activity is very dependent on the pH of adsorption. Cal-B immobilized on PS nanoparticles in buffer solution pH 6.8 performed higher hydrolytic activity than crude enzyme powder and Novozyme 435. %0 lecture %@ %A Elbahri, M. %D 2010 %J %N %P %T Nanochemistry : Aspects and Trends %U %X %0 conference lecture (invited) %@ %A Elbahri, M. %D 2010 %J Seminar von NanoSYD, Mads Clausen Institut %N %P %T Nanochemistry %U %X %0 journal article %@ 0376-7388 %A Homaeigohar, S.S.,Buhr, K.,Ebert, K. %D 2010 %J Journal of Membrane Science %N 1-2 %P 68-77 %R doi:10.1016/j.memsci.2010.08.041 %T Polyethersulfone electrospun nanofibrous composite membrane for liquid filtration %U https://doi.org/10.1016/j.memsci.2010.08.041 1-2 %X A polyethersulfone (PES) electrospun nanofiber mat was evaluated as a membrane for liquid filtration. To alleviate difficult handling of the nanofibrous web and also to provide mechanical strength a poly(ethylene terephthalate) (PET) non-woven was used as the sub-layer. The PES/PET electrospun nanofibrous membranes (ENMs) were characterized in terms of water flux and retention performance. The water flux measurements indicated that the membranes possess a high initial flux. Upon increase of the feed pressure the porosity of the ENFs is deformed resulting in drastically decreased fluxes. To enhance the interfacial stability a heat treatment was performed. Heat treatment approach in addition to enhancement of interfacial stability could preserve the structure of the nanofibrous layer and its effective porosity. Retention tests with polystyrene suspension demonstrated that the filtration performance of the ENMs is highly dependent on size distribution of the suspended particles. When the particles over 1 μm in size (microparticles) are present in the feed, the major rejection of the particles is performed within the first hour of the measurement. The flux is very high and pressure difference very low and almost negligible. In the case of a feed containing only nanoparticles (<1 μm in size), the major rejection is accomplished within the first hour. As a consequence of pore blocking, the flux declines and the pressure difference rises drastically in less. This research demonstrates the filtration potential of electrospun nanofibrous membranes for pre-treatment of water and other liquid separations. %0 conference lecture %@ %A Abdelaziz, R.,Worly, J.,Elbahri, M. %D 2010 %J 4th International Conference of Chemical Industries Research Division %N %P %T Peroxide Nanoparticles for Biomedical Applications %U %X %0 journal article %@ 0255-5476 %A Jebril, S.,Mishra, Y.K.,Elbahri, M.,Kienle, L.,Greve, H.,Quandt, E.,Adelung, R. %D 2010 %J Materials Science Forum, THERMEC 2009 %N %P 2028-2033 %R doi:10.4028/www.scientific.net/MSF.638-642.2028 %T Using thin film stress for nanoscaled sensors %U https://doi.org/10.4028/www.scientific.net/MSF.638-642.2028 %X Thin film stress is often seen as an unwanted effect in micro- and nanostructures. Since recent years, we could employ thin film stress as a useful tool to create nanowires. By creating stress at predetermined breaking points, e.g., in microstructured photo resist thin films, cracks occur on the nanoscale in a well defined and reproducible manner [ ]. By using those as a simple mask for thin film deposition, nanowires can be created. More recently this fabrication scheme could be improved by utilizing delamination of the thin film, in order to obtain suitable shadow masks for thin film deposition in vacuum [ ]. Now, these stress based nanowires can be integrated in microelectronic devices and used as field effect transistors or as hydrogen sensors [ ]. For the functional part of the sensor, it was proposed that thin film stress created by hydrogen adsorption in the nanowire is the driving force. In terms of function, thin films can be also applied on free standing nanoscale whiskers or wires to modify their mechanical features or adding additional functionality. As a second example for the utilization of thin film stress, recent experiments on a piezoelectric and magnetostrictive material combination will be presented. These piezoelectric-magnetostrictive nano-composites are potential candidates for novel magnetic field sensors [ ]. In these composites the magnetostriction will be transferred to the piezoelectric component, resulting in a polarization of the piezoelectric material, that can be used as the sensor signal. The results of two different composite layouts will be presented and discussed with a special focus on the comparison between classical macroscopic composites and the novel nanocomposites. %0 journal article %@ 0022-2461 %A Beyene, H.T.,Chakravadhanula, V.S.K.,Hanisch, C.,Elbahri, M.,Strunskus, T.,Zaporojtchenko, V.,Kienle, L.,Faupel, F. %D 2010 %J Journal of Materials Science %N 21 %P 5865-5871 %R doi:10.1007/s10853-010-4663-5 %T Preparation and plasmonic properties of polymer-based composites containing Ag–Au alloy nanoparticles produced by vapor phase co-deposition %U https://doi.org/10.1007/s10853-010-4663-5 21 %X Nanocomposite (NC) thin films with noble metal nanoparticles (NPs) embedded in a dielectric material show very attractive plasmonic properties due to dielectric and quantum confinement effects. For single component NPs, the plasmon resonance frequency can only be tuned in a narrow range. Much interest aroused in bimetallic NPs, however, many wet chemical approaches often lead to core shell particles, which exhibit multiple plasmon resonances or do not allow large variation of the NPs alloy composition and filling factor. Here, we report a vapor phase co-deposition method to produce polymer–metal NCs with embedded homogeneous Ag–Au alloy particles showing a single plasmon resonance. The method allows production of NPs with controlled alloy composition (x), metal filling (f), and nanostructure in a protecting Teflon AF matrix. The nanostructure size and shape were characterized by transmission electron microscope. Energy dispersive X-ray spectroscopy was used to determine x and f. The optical properties and the position of surface plasmon resonance were studied by UV–Vis spectroscopy. The plasmon resonance can be tuned over a large range of the visible spectrum associated with the change in x, f, and nanostructure. Changes upon annealing at 200 °C are also reported. %0 journal article %@ 0370-1972 %A Gedamu, D.,Jebril, S.,Schuchardt, A.,Elbahri, M.,Wille, S.,Mishra, Y.K.,Adelung, R. %D 2010 %J Physica Status Solidi B %N 10 %P 2571-2580 %R doi:10.1002/pssb.201046199 %T Examples for the integration of self-organized nanowires for functional devices by a fracture approach %U https://doi.org/10.1002/pssb.201046199 10 %X Simple and versatile methods to form nanowires on microchips are of interest for fundamental research and hold the potentials for an industrial fabrication. In this review article, one of these methods based on thin film fracture will be described introducing the experimental parameters and the potential for research. The advantages of the utilization of thin film cracks as a template for the nanowire formation are numerous: nanowire generation ready with contacts, a wide ranging freedom in the choice of materials, influence on the internal structure of the nanowire or the precise positioning on a microchip. A detailed discussion about the fabrication steps and some preliminary experiments revealing the possibilities of the fracture approach will be given for obtained metallic, semiconducting and anodized nanowires. In contrast to their macroscopic counterparts, the conductivity through the nanowires is entirely different. The influence of the surrounding gas atmospheres and the application of electrical fields demonstrate the applicability of these nanowires fabricated by using such a fracture approach. %0 journal article %@ 0887-624X %A Loos, M.R.,Abetz, V.,Schulte, K. %D 2010 %J Journal of Polymer Science A %N 22 %P 5172-5179 %R doi:10.1002/pola.24315 %T Dissolution of MWCNTs by using polyoxadiazoles, and highly effective reinforcement of their composite films %U https://doi.org/10.1002/pola.24315 22 %X Nonmodified multiwalled carbon nanotubes (MWCNTs)/sulfonated polyoxadiazole (sPOD) nanocomposites are successfully prepared by a facile solution route. The pristine MWCNTs are dispersed in a sPOD solution, and the mixtures are fabricated into thin films by solution casting. The homogeneous dispersion of nanotubes in the composites is confirmed by transmission electron microscopy. The mechanical properties, thermal stability, and electrical conductivity are investigated. Tensile strength, elongation at break, and tensile energy to break are shown to increase by more than 28, 45, and 73%, respectively, by incorporating up to 1.0 wt % pristine MWCNTs. The experimental values for sPOD/MWCNTs composite stiffness are compared with Halpin-Tsai and modified Halpin-Tsai predictions. The storage modulus is found to increase up to 10% at low CNT loading. The composite films, which have an outstanding thermal stability, show an increase of up to 57 °C in the initial degradation temperature. The addition of 1.0 wt % MWCNTs increases the electrical conductivity of the sPOD matrix by two orders of magnitude. %0 journal article %@ 1438-1656 %A Faupel, F.,Zaporojtchenko, V.,Strunskus, T.,Elbahri, M. %D 2010 %J Advanced Engineering Materials %N 12 %P 1177-1190 %R doi:10.1002/adem.201000231 %T Metal-Polymer Nanocomposites for Functional Applications %U https://doi.org/10.1002/adem.201000231 12 %X Nanocomposites combine favorable features of the constituents on the nanoscale to obtain new functionalities. The present paper is concerned with the preparation of polymer-based nanocomposites consisting of metal nanoparticles in a polymer matrix and the resulting functional properties. Emphasis is placed on vapor phase deposition which inter alia allows the incorporation of alloy clusters with well defined composition and tailored filling factor profiles. Examples discussed here include optical composites with tuned particle surface plasmon resonances for plasmonic applications, magnetic high frequency materials with cut-off frequencies well above 1 GHz, sensors that are based on the dramatic change in the electronic properties near the percolation threshold, and antibacterial coatings which benefit from the large effective surface of nanoparticles and the increased chemical potential which both strongly enhance ion release. %0 conference lecture (invited) %@ %A Elbahri, M. %D 2010 %J 4th International Conference of Chemical Industries Research Division %N %P %T Nanochemistry : Aspects and Trends %U %X %0 journal article %@ 1436-2597 %A Wozny, G.,Brinkmann, T. %D 2009 %J CITplus : Das Praxismagazin fuer Verfahrens- und Chemieingenieure %N 7-8 %P 30-32 %T Mehr als eine Nischenloesung - Energie sparen durch den Einsatz von Membranen %U 7-8 %X Energieeffizienz spielt besonders im Bereich der thermischen Trenn-verfahren eine immer wichtigere Rolle. Stei-gende Energie- und Rohstoffkosten, sowie strengere Umweltaufla-gen und höhere Quali-tätsvorgaben verlangen nach innovativen Kon-zepten und neuen Pro-zessen. Hierbei spielen Hybridverfahren eine immer bedeutendere Rolle, und stellen heut-zutage weit mehr als ei-ne Nischenlösung dar. %0 journal article %@ 1744-683X %A Jinnai, H.,Kaneko, T.,Matsunaga, K.,Abetz, C.,Abetz, V. %D 2009 %J Soft Matter %N 10 %P 2042-2046 %R doi:10.1039/b901008d %T A double helical structure formed from an amorphous, achiral ABC triblock terpolymer %U https://doi.org/10.1039/b901008d 10 %X We present the experimental visualization of the three-dimensional (3D) helical morphology of a polystyrene-block-polybutadiene-block-poly(methyl methacrylate) triblock terpolymer (SBM) using transmission electron microtomography. Our results uncovered a left-handed (and to a similar degree, right-handed) double helical structure composed of polybutadiene (PB) helical microdomains around polystyrene (PS) cores. The addition of short polystyrene chains into the PS cores by solution blending was found to be essential to control the pitch of the helix. We further discovered that the self-assembly in thin films of the present helical structure forms a thickness-independent stable alignment of the helical fibers arrayed in a honeycomb board perpendicular to the film plane. %0 journal article %@ 1530-6984 %A Walther, A.,Yuan, J.,Abetz, V.,Mueller, A.H. %D 2009 %J Nano Letters %N 5 %P 2026-2030 %R doi:10.1021/nl9002975 %T Structure-Tunable Bidirectional Hybrid Nanowires via Multicompartment Cylinders %U https://doi.org/10.1021/nl9002975 5 %X We present structure-tunable bidirectional inorganic−organic hybrid nanowires templated by soft multicompartment cylinders, possessing perfectly parallel compartments. The poly(2-vinylpyridine) compartments are used to bind nanoparticles via supramolecular coordination. The resulting hybrid nanowires are tunable in terms of the distribution of the inorganics in the corona. The two limiting cases are (a) perfectly aligned, parallel nanowires and (b) nanowires with one homogeneous corona. This approach demonstrates how advances in polymer architectures can be used to create novel hybrid materials of unprecedented complexity and very desirable architecture. %0 journal article %@ 0266-3538 %A Gomes, D.,Loos, M.R.,Wichmann, M.H.G.,de la Vega, A.,Schulte, K. %D 2009 %J Composites Science and Technology %N 2 %P 220-227 %R doi:10.1016/j.compscitech.2008.10.008 %T Sulfonated polyoxadiazole composites containing carbon nanotubes prepared via in situ polymerization %U https://doi.org/10.1016/j.compscitech.2008.10.008 2 %X In the present work, in situ polymerizations of sulfonated polyoxadiazole through a polycondensation reaction of A–A (hydrazine sulphate) and B–B (aromatic dicarboxylic acid) monomers with carbon nanotubes in poly(phosphoric acid) were performed. The structures of composites were characterized by elemental analysis, Raman and FTIR spectroscopy. The sulfonated polyoxadiazole composites with high molecular weight (in the order of magnitude of 105 g/mol) are soluble in organic solvents and can be cast as dense films. They exhibit good mechanical properties (storage modulus up to around 4 GPa at 300 °C) and an electrical conductivity in the order of 10−5 S m−1. The composites can be used at temperatures as high as 470 °C. %0 journal article %@ 0021-8995 %A Boschetti de Fierro, A.,Pardey, R.,Savino, V.,Mueller, A. %D 2009 %J Journal of Applied Polymer Science %N 6 %P 2851-2858 %R doi:10.1002/app.29335 %T Piezoresistive behavior of epoxy matrix-carbon fiber composites with different reinforcement arrangements %U https://doi.org/10.1002/app.29335 6 %X In this work, the self-monitoring capability of epoxy matrix-carbon fiber composites has been studied. Different concentrations and arrangements of reinforcements were used, including random chopped, unidirectional and bi-directional continuous carbon fibers, weaved and nonweaved. Mechanical properties were determined by uniaxial tensile tests. The composite electric to mechanical behavior was established by determining its electrical resistivity variation as a function of the stress-strain curve. It was observed that the composites electrical resistance increased during tensile tests, a trend that indicates piezoresistive behavior. The increase was linear for the chopped reinforced composites, while it exhibits different slopes in the continuous reinforced composites. The initial smaller slope corresponds mainly to separation of the 90° oriented fibers and/or transversal cracking of the matrix, whereas the latter higher slope is caused by fiber fracture. The results demonstrated how each reinforcement configuration exhibited a unique and typical electrical response depending on the specific reinforcement, which might be appropriate either for strain-monitoring or damage-monitoring. %0 journal article %@ 0954-0083 %A Loos, M.R.,Gomes, D. %D 2009 %J High Performance Polymers %N 6 %P 697-708 %R doi:10.1177/0954008308097458 %T The Effect of Sulfonation Level and Molecular Weight on the Tensile Properties of Polyoxadiazoles %U https://doi.org/10.1177/0954008308097458 6 %X The tensile properties of sulfonated polyoxadiazoles were studied as a function of molecular weight and sulfonation level. All sulfonated polyoxadiazoles synthesized through a polycondensation reaction of the hydrazine sulphate salt and a dicarboxylic acid in poly(phosphoric acid) exhibit rigid-ductile behavior with high Young’s modulus (3–4 GPa) and with larger elongations at break (up to 120%). Sulfonated,polyoxadiazoles with maximum reproducible tensile strength (190 6.9 MPa) could be synthesized in the frame of time of 4–5 h. %0 journal article %@ 0022-3093 %A Prado, L.A.S.de A.,Ponce, M.L.,Goerigk, G.,Funari, S.S.,Haramus, V.,Willumeit, R.,Schulte, K.,Pereira Nunes, S. %D 2009 %J Journal of Non-Crystalline Solids %N 1 %P 6-11 %R doi:10.1016/j.jnoncrysol.2008.09.036 %T Analysis of proton-conducting organic–inorganic hybrid materials based on sulphonated poly(ether ether ketone) and phosphotungstic acid via ASAXS and WAXS %U https://doi.org/10.1016/j.jnoncrysol.2008.09.036 1 %X In the present paper the distribution of phosphotungstic acid (PTA, H3PW12O40) dispersed in sulfonated poly(ether ether ketone), SPEEK, was investigated by Anomalous Small Angle X-ray scattering (ASAXS) and Wide-Angle X-Ray Scattering WAXS techniques. The hydrolysis and condensation of 3-aminopropyltrimethoxysilane or zirconium tetrapropylate in this polymeric matrix were used to produce poly(3-aminopropyl silsesquioxane) or ZrO2, as nanofillers. Contrary to previous results reported for membranes containing phosphomolybdic acid, the PTA could be completely dissolved in the SPEEK matrix. The applicability of the Guinier approximation for the SPEEK/PTA membrane confirmed that the PTA was dispersed as isolated nanoparticles. The incorporation of poly(3-aminopropyl silsesquioxane) in the SPEEK/PTA system caused the agglomeration of the heteropolyacid as 30 nm large particles. The ZrO2 had little effect on the distribution of PTA in the SPEEK matrix. On the other hand, no crystallization of the heteropolyacid was observed in the membranes. %0 journal article %@ 0167-577X %A Loos, M.R.,Gomes, D. %D 2009 %J Materials Letters %N 8 %P 694-696 %R doi:10.1016/j.matlet.2008.11.042 %T In situ-polymerization of fluorinated polyoxadiazole with carbon nanotubes in poly(phosphoric acid) %U https://doi.org/10.1016/j.matlet.2008.11.042 8 %X In the present work, in-situ polymerizations of fluorinated polyoxadiazole through a polycondensation reaction of A–A (hydrazine sulphate) and B–B (aromatic dicarboxylic acid) monomers with multiwalled carbon nanotubes (MWCNT) in poly(phosphoric acid) were performed in the frame of time 3 to 48 h. The effect of acid treatment in polyphosphoric acid on the CNT structure was analyzed by SEM, TGA and FTIR. Fluorinated polyoxadiazole/MWCNTs soluble in organic solvents with high molecular weights (around 200 000 g/mol) could be synthesized in 3 h. The fluorinated polyoxadiazole/MWCNTs exhibits high thermal stability with degradation temperature at about 460 °C. %0 journal article %@ 0002-7863 %A Walther, A.,Drechsler, M.,Rosenfeldt, S.,Harnau, L.,Ballauff, M.,Abetz, V.,Mueller, A.H.E. %D 2009 %J Journal of the American Chemical Society %N 13 %P 4720-4728 %R doi:10.1021/ja808614q %T Self-Assembly of Janus Cylinders into Hierarchical Superstructures %U https://doi.org/10.1021/ja808614q 13 %X We present in-depth studies of the size tunability and the self-assembly behavior of Janus cylinders possessing a phase segregation into two hemicylinders. The cylinders are prepared by cross-linking the lamella-cylinder morphology of a polystyrene-block-polybutadiene-block-poly(methyl methacrylate) block terpolymer. The length of the Janus cylinders can be adjusted by both the amplitude and the duration of a sonication treatment from the micro- to the nanometer length. The corona segregation into a biphasic particle is evidenced by selective staining of the PS domains with RuO4 and subsequent imaging. The self-assembly behavior of these facial amphiphiles on different length scales is investigated combining dynamic light scattering (DLS), small-angle neutron scattering (SANS), and imaging procedures. Cryogenic transmission electron microscopy images of the Janus cylinders in THF, which is a good solvent for both blocks, exhibit unimolecularly dissolved Janus cylinders with a core−corona structure. These results are corroborated by SANS measurements. Supramolecular aggregation takes place in acetone, which is a nonsolvent for polystyrene, leading to the observation of fiber-like aggregates. The length of these fibers depends on the concentration of the solution. A critical aggregation concentration is found, under which unimolecularly dissolved Janus cylinders exist. The fibers are composed of 2−4 Janus cylinders, shielding the inner insoluble polystyrene hemicylinder against the solvent. Herein, the SANS data reveal a core−shell structure of the aggregates. Upon deposition of the Janus cylinders from more concentrated solution, a second type of superstructure is formed on a significantly larger length scale. The Janus cylinders form fibrillar networks, in which the pore size depends on the concentration and deposition time of the sample. %0 journal article %@ 0947-6539 %A Schoeps, D.,Buhr, K.,Dijkstra, M.,Ebert, K.,Plenio, H. %D 2009 %J Chemistry - A European Journal %N 12 %P 2960-2965 %R doi:10.1002/chem.200802153 %T Batchwise and Continuous Organophilic Nanofiltration of Grubbs-Type Olefin Metathesis Catalysts %U https://doi.org/10.1002/chem.200802153 12 %X A mass-tagged N-mesityl imidazolinium salt with four additional -CH2NCy2 substituents was synthesized, leading to a molecular mass of nearly 1100 g mol-1 in the corresponding carbene ligand. This mass-tagged ligand was used to generate the respective Grubbs II and Grubbs-Hoveyda type complexes. The catalytic activity of the latter complex was tested in several olefin metathesis reactions and found to be slightly superior to that of the related N-mesityl based complex. In batchwise solvent resistant nanofiltration experiments the ruthenium complex dissolved in toluene and following a metathesis reactions was efficiently retained (>99.8 %) by a single nanofiltration; the permeate contained less than 4 ppm of Ru. Equally efficient catalyst retention was observed in a membrane reactor utilized for the continuous synthesis of a RCM product. %0 journal article %@ 0942-9352 %A Suleiman, M.,Borchers, C.,Guerdane, M.,Jisrawi, N.M.,Fritsch, D.,Kirchheim, R.,Pundt, A. %D 2009 %J Zeitschrift fuer Physikalische Chemie %N 1-2 %P 169-182 %R doi:10.1524/zpch.2009.6031 %T Size and Structure of Palladium Clusters Determined by XRD and HREM %U https://doi.org/10.1524/zpch.2009.6031 1-2 %X Scherrer formula is often applied to X-ray-diffraction profiles for the size determination of small size clusters. However, for small clusters this often leads to conflicting results in comparison to other methods. A series of Pd-clusters of different size is studied by X-ray diffraction analysis and transmission electron microscopy. The influence of size and structure on the results is presented and discussed in comparison with theoretical calculations. It will be shown that the different structure of small size systems are one main origin of the conflicts. The structure problem can be overcome by using Fourier Transform of the X-ray diffraction pattern. The importance of the knowledge of the cluster structure was demonstrated by showing its strong influence on the hydrogen solubility. %0 journal article %@ 0004-9425 %A Fierro, D.,Buhr, K.,Abetz, C.,Boschetti de Fierro, A.,Abetz, V. %D 2009 %J Australian Journal of Chemistry %N 8 %P 885-890 %R doi:10.1071/CH09094 %T New Insights into the Control of Self-Assembly of Block Copolymer Membranes %U https://doi.org/10.1071/CH09094 8 %X The preparation and morphological characterization of a so-called composite membrane based on a 3-miktoarm star terpolymer on a support layer is reported. It is demonstrated that different levels of order and different morphological orientations can be obtained by directly casting the star terpolymer solution on the support, depending on the prior treatment of the support layer and the casting conditions. %0 journal article %@ 1615-6846 %A Maab, H.,Schieda, M.,Yave, W.,Shishatskiy, S.,Pereira Nunes, S. %D 2009 %J Fuel Cells %N 4 %P 401-409 %R doi:10.1002/fuce.200800121 %T SPEEK/Polyimide Blends for Proton Conductive %U https://doi.org/10.1002/fuce.200800121 4 %X A series of membranes, based on sulphonated poly(ether ether ketone) (SPEEK)/polyimide (PI) blends, was prepared at different casting conditions. They were characterised by SEM, FTIR, DMTA, DSC, TGA, water/methanol pervaporation and impedance spectroscopy. The membranes prepared at 130 °C from blends with 10, 20 and 30 wt.-% of PI are homogeneous, and the methanol permeabilities decreased from 28 × 10-10 kg m s-1 m-2 (plain SPEEK) to 7.21, 2.61 and 0.55 × 10-10 kg m s-1 m-2, respectively. This corresponds to a 4- to 57-fold methanol crossover reduction. With this improvement, by the introduction of PI, the power density of SPEEK-based membranes in DMFC tests could be greatly improved. %0 journal article %@ 0024-9297 %A Ghanem, B.S.,McKeown, N.B.,Budd, P.M.,Al-Harbi, N.M.,Fritsch, D.,Heinrich, K.,Starannikova, L.,Tokarev, A.,Yampolskii, Y. %D 2009 %J Macromolecules %N 20 %P 7881-7888 %R doi:10.1021/ma901430q %T Synthesis, Characterization, and Gas Permeation Properties of a Novel Group of Polymers with Intrinsic Microporosity: PIM-Polyimides %U https://doi.org/10.1021/ma901430q 20 %X A range of polyimides with characteristics similar to a polymer of intrinsic microporosity (PIM) were prepared by reaction with various aromatic diamines of a bis(carboxylic anhydride) incorporating a spiro-center. The polymers exhibited high surface area, as determined by nitrogen adsorption, and high thermal stability. Membrane gas permeation experiments showed PIM-polyimides to be among the most permeable of all polyimides and to have selectivities close to the upper bound for several important gas pairs. A group contribution method was used to predict permeability coefficients and separation factors for further PIM-polyimide structures, revealing worthwhile targets for future synthetic efforts. %0 journal article %@ 1550-6703 %A Fierro, D.,Boschetti de Fierro, A.,Abetz, V. %D 2009 %J PMSE Preprints %N %P 985 %T Formation of Nanoporous Membranes from Block Copolymer Solutions %U %X The use of block copolymer membranes is of important interest in many applications. In order to fabricate a block copolymer membrane, different approaches have been used. Yang et al. prepared a block copolymer thin layer with hexagonally packed perpendicular oriented cylinders on a sacrificial silicon oxide layer from solution. After drying they transferred the block copolymer thin layer onto a microfiltration polysulfone membrane, which acts as a mechanically stable support and showed its potential for protein filtration.[1] A recently published,approach consists of the preparation of a block copolymer membrane,with an asymmetric morphology by combining the nonsolvent induced,phase separation process and the self-assembly ability. The asymmetric structure consisted of a nonordered porous structure covered by a layer of ca. 250 nm thickness with hexagonally ordered cylindrical pores.[2],In the present work we study the direct casting of block copolymer,solutions onto a mechanically stable porous material. By combining the,self-assembly ability of block copolymers, the morphology generation in thin films and the porous material support, it is expected to obtain a continuous and uniform selective layer with slight interpenetration into the porous support that provides mechanical strength to the membrane. In this first work the aim is to obtain a continuous thin block copolymer layer on top of the substrate. %0 journal article %@ 1550-6703 %A Fritsch, D.,Heinrich, K.,Bengtson, G. %D 2009 %J PMSE Preprints %N %P 761-762 %T Polymers of Intrinsic Microporosity: Copolymers, improved Synthesis and Applications as Membrane Separation Material %U %X Intrinsic microporosity is one of the most important properties of high free volume polymers. If one arranges all known polymers by increasing free volume in a continuous line, at the endpoint, merely a very few polymers with extremely high free volume of above 20% can be named. Today, only some polyacetylenes (best known polytrimethylsilylpropyne (PTMSP)), Teflon copolymers (Teflon® AF-types, Hyflon® AD), one silylated polynorbornene and PIM polymers are identified. PIM polymers, known since 2004 [1], are ladder type polycondensates composed of flat dioxane rings and sites of contortion. Their exceptional basic properties as membrane separation materials have been recovered recently [2]. %0 journal article %@ 1060-1325 %A Kricheldorf, H.R.,Behnken, G.,Schwarz, G.,Simon, P.,Brinkmann, M. %D 2009 %J Journal of Macromolecular Science A %N 4 %P 353-359 %R doi:10.1080/10601320902724800 %T High Molar Mass Poly(trimethylene carbonate) by Ph2BiOEt and Ph2BiBr-Initiated Ring-Opening Polymerizations %U https://doi.org/10.1080/10601320902724800 4 %X Trimethylene carbonate, (TMC), was polymerized in bulk with Ph2BiOEt or Ph2BiBr as initiators. The dependence of the molecular weight on the monomer-initiator ratio (M/I) and the MALDI-TOF (MT) mass spectra suggest that these polymerizations obey a coordination-insertion mechanism. Due to “back-biting” cyclic oligomers were also formed. With Ph2BiBr particularly high molecular weights were achieved (number averages, Mns, up to 340 times 103 Da), but the Mns were significantly higher than the M/Is. However, a satisfactory control of Mn was achieved by addition of tetraethylene glycol as coinitiator. In the case of Ph2BiOEt the Mns fell below the M/Is and only a crude control of the Mns was achieved. Both Bi-compounds were more reactive than Sn(II)2-ethylhexanoate (SnOct2) activated with ethanol. This difference was particularly conspicuous at temperatures below 100°C. %0 journal article %@ 0149-6395 %A Nistor, C.,Shishatskiy, S.,Popa, M.,Pereira Nunes, S. %D 2009 %J Separation Science and Technology %N 14 %P 3392-3411 %R doi:10.1080/01496390903212698 %T Organic-Inorganic CO2 Selective Membranes Prepared by the Sol-Gel Process %U https://doi.org/10.1080/01496390903212698 14 %X Composite membranes prepared from mixtures of 3-glycidoxypropyl trimethoxysilane (GPTMS) and different diamines containing polyether segments were synthesized by the sol-gel process. The membranes were obtained by coating asymmetric porous polyacrylonitrile (PAN) supports with the silane solutions. The composite membranes were characterized by single and mixed gas permeation and by atomic force microscopy. The selectivity increased by increasing the molecular weight of the poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol)bis(2-aminopropyl ether) (PAPE), and also with the addition of poly(ethylene glycol) (PEG) to the coating solution. The CO2/N2 selectivity values up to 75 and the CO2/CH4 selectivity values up to 20 were measured. High gas selectivity was also confirmed by measurements with mixed gas feed, although slightly lower than in the measurements with single gases. %0 journal article %@ 0376-7388 %A Maab, H.,Shishatskiy, S.,Pereira Nunes, S. %D 2009 %J Journal of Membrane Science %N 1 %P 27-35 %R doi:10.1016/j.memsci.2008.09.014 %T Preparation and characterization of bilayer carbon/polymer membranes %U https://doi.org/10.1016/j.memsci.2008.09.014 1 %X The objective of the present research work was to develop a membrane with a high H2O/alcohol selectivity for pervaporation and for use in direct alcohol fuel cells. Sulfonated poly (ether ether ketone) (SPEEK) was coated with a thin continuous carbon molecular sieve (CMS) layer. The membranes obtained had 180- and 400-nm thick CMS layers that led to a clear reduction of alcohol crossover. The water/alcohol selectivity increased with the size of the alcohol molecules as follows: methanol < ethanol < n-propanol < iso-propanol. A water/n-propanol selectivity of up to 34,000 was obtained, confirming the molecular sieving effect. The system was tested in a direct methanol fuel cell using standard electrodes, and demonstrated a better performance than with plain membranes. In a later stage Pt was introduced in the CMS layer during the preparation of the membrane electrode assemblies, this had the advantage that the CMS layer not only acted as an alcohol barrier but also as a catalyst support. %0 conference lecture %@ %A Elbahri, M. %D 2009 %J Nanotech Europe 2009 %N %P %T Green nanosynthesis and nanopatterning using a drop on a hot plate %U %X %0 conference lecture %@ %A Jebril, S.,Mishra, Y.K.,Elbahri, M.,Kienle, L.,Greve, H.,Quandt, E.,Adelung, R. %D 2009 %J International Conference on Processing and Manufacturing of Advanced Materials, THERMEC 2009 %N %P %T Using thin film stress for nanoscaled sensors %U %X %0 journal article %@ 0376-7388 %A Pezzin, S.,Stock, N.,Shishatskiy, S.,Pereira Nunes, S. %D 2008 %J Journal of Membrane Science %N 2 %P 559-569 %R doi:10.1016/j.memsci.2008.08.010 %T Modification of proton conductive polymer membranes with phosphonated polysilsesquioxanes %U https://doi.org/10.1016/j.memsci.2008.08.010 2 %X New hybrid membranes for fuel cell applications based on sulfonated poly(ether ether ketone) (SPEEK) and phosphonated polysilsesquioxanes were synthesized. The impedance spectroscopy measurements show an increase of the proton conductivity for all studied composites, in comparison to plain SPEEK. For hybrid membranes containing 20 wt% of polysilsesquioxane with 80 mol% of phosphonated units the conductivities can reach values that are similar to Nafion 117® at 100% RH. The best results of proton conductivity (142 mS/cm) were obtained for composites with 40 wt% of the same polysilsesquioxane at 120 °C also at 100% RH. %0 journal article %@ 1862-5282 %A Suleiman, M.,Fritsch, D.,Borchers, C.,Guerdane, M.,Pundt, A. %D 2008 %J International Journal of Materials Research %N 5 %P 528-534 %R doi:10.3139/146.101670 %T Hydrogen absorption in 3.1 nanometre sized palladium samples: Does structure matter? %U https://doi.org/10.3139/146.101670 5 %X In this work the hydrogen absorption behaviour of two types of Pd-clusters, different in structure but similar in size (3.1 nm), will be presented. First, icosahedral Pd clusters stabilised in surfactants; second, cubic Pd clusters stabilised in a Teflon-AF matrix. The phase transition in these samples was monitored by in-situ X-ray diffraction. It will be shown that the hydrogen uptake ability depends strongly on the lattice structure, which is affected by the type of stabiliser. Teflon AF stabilised clusters (cubic clusters) show the phase transition which is common for bulk Pd, whereas the surfactant stabilised clusters (icosahedral clusters) show only weak lattice dilatation upon hydrogen absorption. Pressure–lattice parameter isotherms show that the cubic clusters absorb large amounts of hydrogen in comparison to the icosahedral clusters. The measured lattice expansion is 0.130 Å at 105 Pa and 300 K, which is about 320% the amount measured for icosahedral clusters (0.04 Å). This suggests that surface sites are available for hydrogen in the Pd–Teflon-AF samples which are not accessible for Pd–surfactant-clusters, and that the icosahedral lattice absorbs less hydrogen for similar external pressures. %0 journal article %@ 0376-7388 %A Prehn, K.,Adelung, R.,Heinen, M.,Pereira Nunes, S.,Schulte, K. %D 2008 %J Journal of Membrane Science %N 1 %P 123-130 %R doi:10.1016/j.memsci.2008.04.041 %T Catalytically active CNT–polymer-membrane assemblies: From synthesis to application %U https://doi.org/10.1016/j.memsci.2008.04.041 1 %X A new membrane electrode assembly set up for catalytic processes containing carbon nanotubes has been developed. The process includes the nanotube synthesis, sputter deposition of platinum as catalyst and the membrane casting. Aligned nanotube carpets were grown from toluene/ferrocene solutions and sputtered with platinum. Subsequently the assembly was investigated using cyclic voltammetry to confirm a sufficient catalyst activity. A procedure was developed to embed the carbon nanotubes doped with catalyst into SPEEK membranes, while preserving the aligned structure and keeping some surface area of the catalyst-doped nanotubes free of membrane material to allow for easy access to reactants. So far the best results were obtained using an aligned but somewhat loose nanotube structure and a deposition of 0.034 mg/cm2 Pt, forming a combination of small catalyst clusters and a thin film. The assemblies are optimized in respect to application in fuel cells and functional membranes. %0 journal article %@ 0376-7388 %A Gomes, D.,Pereira Nunes, S. %D 2008 %J Journal of Membrane Science %N 1 %P 114-122 %R doi:10.1016/j.memsci.2007.11.041 %T Fluorinated polyoxadiazole for high-temperature polymer electrolyte membrane fuel cells %U https://doi.org/10.1016/j.memsci.2007.11.041 1 %X For the first time a fluorinated polyoxadiazole doped with phosphoric acid as a proton-conducting membrane for operation at temperatures above 100 °C and low humidities for fuel cells has been reported. Fluorinated polyoxadiazole with remarkable chemical stability was synthesized. No changes in the molecular weight (about 200,000 g mol−1) can be observed when the polymer is exposed for 19 days to mixtures of sulfuric acid and oleum. Protonated membranes with low doping level (0.34 mol of phosphoric acid per polyoxadiazole unit, 11.6 wt.% H3PO4) had proton conductivity at 120 °C and RH = 100% in the order of magnitude of 10−2 S cm−1. When experiments are conducted at lower external humidity, proton conductivity values drop an order of magnitude. However still a high value of proton conductivity (6 × 10−3 S cm−1) was obtained at 150 °C and with relative humidity of 1%. In an effort to increase polymer doping, nanocomposite with sulfonated silica containing oligomeric fluorinated-based oxadiazole segments has also been prepared. With the addition of functionalized silica not only doping level but also water uptake increased. For the nanocomposite membranes prepared with the functionalized silica higher proton conductivity in all range of temperature up to 120 °C and RH = 100% (in the order of magnitude of 10−3 S cm−1) was observed when compared to the plain membrane (in the order of magnitude of 10−5 S cm−1). %0 journal article %@ 0376-7388 %A Guzman-Gutierrez, M.T.,Zolotukhin, M.G.,Fritsch, D.,Ruiz-Trevino, F.A.,Cedillo, G.,Fregoso-Israel, E.,Ortiz-Estrada, C.,Chavez, J.,Kudla, C. %D 2008 %J Journal of Membrane Science %N 2 %P 379-385 %R doi:10.1016/j.memsci.2008.06.041 %T Synthesis and Gas transport Properties of New Aromatic 3F-Polymers %U https://doi.org/10.1016/j.memsci.2008.06.041 2 %X New aromatic 3F polymers were obtained from condensations of 2,2,2-trifluoroacetophenone (1),with biphenyl (a), terphenyl (b), a mixture of biphenyl with terphenyl (ab), phenyl ether (c) and,diphenoxybenzophenone (d). The reactions were performed at room temperature in the Brønsted,superacid trifluoromethanesulfonic acid (TFSA) and in a mixture of TFSA with dichloromethane. The polymers show high glass transition temperatures > 170 ºC, excellent,thermal stability (decomposition temperatures ≥ 475 ºC) and good solubility in chlorinated solvents and strong acids. The 3F polymer structures based on biphenyl and terphenyl show attractive permeability coefficients for CO2 (-200 Barrers) and H2 (-120 Barrers), whereas the 3F polymers that contain ether linkages have permeability coefficients in the typical range of regular polysulfone and polycarbonate. However, in sharp contrast to polysulfone and,polycarbonate families, new 3F polymers posses high chemical stability and they have,advantages since their reactions, based on commercially available monomers, can be carried out,in one-pot at room temperature and offer a large variety of structures not possible to prepare by,other synthetic methods. %0 journal article %@ 0011-9164 %A Brinkmann, T.,Scholles, C.,Wind, J.,Wolff, T.,Dengel, A.,Clemens, W. %D 2008 %J Desalination %N 1-3 %P 7-11 %R doi:10.1016/j.desal.2007.02.079 %T Processing of coal mine gas with low methane concentrations for use in high temperature fuel cells %U https://doi.org/10.1016/j.desal.2007.02.079 1-3 %X Coal mines are emitting off-gases containing methane of varying content. For environmental as well as economical reasons the gas should be collected and put to further use, i.e., as a feed stock for gas engines or fuel cells. Certain concentration ranges of the coal mine gas require an adjustment of the methane content due to safety related and technical constraints. The application of gas permeation is one possibility to increase the methane content to the desired levels. Employing methane selective, silicone-based, high-flux membranes is currently being investigated by a German project consortium. Experimental results as well as simulation studies showed that selectivity and flux of the membrane are sufficient to increase the methane content to the desired value at a reasonable recovery. %0 journal article %@ 0024-9297 %A Ghanem, B.S.,McKeown, N.B.,Budd, P.M.,Fritsch, D. %D 2008 %J Macromolecules %N 5 %P 1640-1646 %R doi:10.1021/ma071846r %T Polymers of Intrinsic Microporosity Derived from Bis(phenazyl) Monomers %U https://doi.org/10.1021/ma071846r 5 %X Novel polymers of intrinsic microporosity (PIMs) are prepared from bis(phenazyl) monomers derived from readily available bis(catechol)s. One of the polymers (termed PIM-7) has an excellent combination of properties with high internal surface area, good film-forming characteristics, and gas transport properties that make it a suitable candidate for gas separation membranes. The high gas permeability and good ideal selectivity of PIM-7 place it above Robeson's upper-bound for a number of commercially important gas pairs (e.g., O2/N2, CO2/CH4, and CO2/N2). %0 journal article %@ 0024-9297 %A Castillo, R.V.,Arnal, M.L.,Mueller, A.J.,Hamley, I.W.,Castelleto, V.,Schmalz, H.,Abetz, V. %D 2008 %J Macromolecules %N 3 %P 879-889 %R doi:10.1021/ma0718907 %T Fractionated Crystallization and Fractionated Melting of Confined PEO Microdomains in PB-Beta-PEO and PE-Beta-PEO Diblock Copolymers %U https://doi.org/10.1021/ma0718907 3 %X The confined crystallization of poly(ethylene oxide) (PEO) in predominantly spherical microdomains formed by several diblock copolymers was studied and compared. Two polybutadiene-b-poly(ethylene oxide) diblock copolymers were prepared by sequential anionic polymerization (with approximately 90 and 80 wt % polybutadiene (PB)). These were compared to equivalent samples after catalytic hydrogenation that produced double crystalline polyethylene-b-poly(ethylene oxide) diblock copolymers. Both systems are segregated into microdomains as indicated by small-angle X-ray scattering (SAXS) experiments performed in the melt and at lower temperatures. However, the PB-b-PEO systems exhibited a higher degree of order in the melt. A predominantly spherical morphology of PEO in a PB or a PE matrix was observed by both SAXS and transmission electron microscopy, although a possibly mixed morphology (spheres and cylinders) was formed when the PEO composition was close to the cylinder-sphere domain transitional composition as indicated by SAXS. Differential scanning calorimetry experiments showed that a fractionated crystallization process for the PEO occurred in all samples, indicating that the PE cannot nucleate PEO in these diblock copolymers. A novel result was the observation of a subsequent fractionated melting that reflected the crystallization process. Sequential isothermal crystallization experiments allowed us to thermally separate at least three different crystallization and melting peaks for the PEO microdomains. The lowest melting point fraction was the most important in terms of quantity and corresponded to the crystallization of isolated PEO spheres (or cylinders) that were either superficially or homogeneously nucleated. This was confirmed by Avrami index values of approximately 1. The isothermal crystallization results indicate that the PE matrix restricts the crystallization of the covalently bonded PEO to a higher degree compared to PB. %0 journal article %@ 0009-286X %A Brinkmann, T.,Pingel, H.,Wolff, T. %D 2008 %J Chemie - Ingenieur - Technik %N 1-2 %P 157-164 %R doi:10.1002/cite.200700170 %T Verhalten verschiedener Membranmaterialien fuer die Aufbreitung organischer Produktstroeme aus Reaktivrektifikationskolonnen %U https://doi.org/10.1002/cite.200700170 1-2 %X In dieser Arbeit werden verschiedene kommerziell erhältliche sowie sich in der Entwicklung befindliche Membranmaterialien für die Trennung von Methanol/Methylacetatgemischen charakterisiert, die z. B. als Kopfprodukt in Reaktivrektifikationskolonnen anfallen. Das Permeationsverhalten der Membranmaterialien wurde sowohl in der Pervaporation als auch in der Dampfpermeation untersucht. Ferner dienten die Ergebnisse der Dampfpermeationsmessungen für eine Simulation des Trennverfahrens. %0 journal article %@ 1549-3296 %A Ajami-Henriquez, D.,Rodriguez, M.,Sabino, M.,Castillo, R.V.,Mueller, A.J.,Boschetti de Fierro, A.,Abetz, C.,Abetz, V.,Dubois, P. %D 2008 %J Journal of Biomedical Materials Research A %N 2 %P 405-417 %R doi:10.1002/jbm.a.31796 %T Evaluation of cell affinity on poly(Jota-lactide) and poly(Epsilon-caprolactone) blends and on PLLA-Beta-PCL diblock copolymer surfaces %U https://doi.org/10.1002/jbm.a.31796 2 %X An evaluation of cell proliferation and adhesion on biocompatible film supports was performed. A series of films were compression molded from commercially available poly (L-lactide), PLLA, and poly(-caprolactone), PCL, and from their melt mixed blends (PLLA/PCL blends). These were compared with compression molded films of PLLA-b-PCL model diblock copolymers. The samples were analyzed by differential scanning calorimetry (DSC), contact angle measurements, and scanning force microscopy (SFM). Cell adhesion and proliferation were performed with monkey derived fibroblasts (VERO) and with osteoblastic cells obtained either enzymatically or from explants cultures of Sprague-Dawley rat calvaria. Migration studies were performed with bone explants of the same origin. The results obtained indicate that although all materials tested were suitable for the support of cellular growth, a PLLA-b-PCL diblock copolymer sample with 93% PLLA was significantly more efficient. This sample exhibited a unique surface morphology with long range ordered domains (of the order of 2-3 m) of edge-on PLLA lamellae that can promote cell contact guidance. The influence of other factors such as chemical composition, degree of crystallinity, and surface roughness did not play a major role in determining cell preference toward a specific surface for the materials employed in this work. %0 journal article %@ 0378-7753 %A Gomes, D.,Roeder, J.,Ponce, M.L.,Pereira Nunes, S. %D 2008 %J Journal of Power Sources %N 1 %P 49-59 %R doi:10.1016/j.jpowsour.2007.09.090 %T Single-Step Synthesis of Sulfonated Polyoxadiazoles and their Use as Proton Conducting Membranes %U https://doi.org/10.1016/j.jpowsour.2007.09.090 1 %X A single-step approach for the synthesis of sulfonated polyoxadiazoles from hydrazine sulfate was developed using non-sulfonated diacids in polyphosphoric acid. The post-sulfonation conditions were optimized by varying reaction time, medium and reagent concentrations in sulfuric acid, oleum and/or their mixtures. For the first time, a series of sulfonated polyoxadiazoles with ion exchange capacity (IEC) ranging from 1.26,to 2.7 meqiv. g−1 and high molecular weight (about 40,0000 g mol−1) were synthesized. The structures of the polymers were characterized by,elemental analysis, 1H NMR, and FTIR. Sulfonated polyoxadiazole membranes with high thermal stability indicated by observed glass-transition temperatures (Tg) ranging from 364 to 442 ◦C in sodium salt form and from 304 to 333 ◦C in acid form and with high mechanical properties (storage modulus about 3GPa at 300 ◦C) have been prepared. The membrane stability to oxidation was investigated by soaking the film in Fenton’s reagent at 80 ◦C for 1 h. The sulfonated polyoxadiazole membranes exhibited high oxidative stability, retaining 98–100% of their weight after the test. Proton conductivity values with the order of magnitude of 10−1 to 10−2 S cm−1 at 80 ◦C and with relative humidity ranging from 100% to 20%,were obtained. %0 journal article %@ 0376-7388 %A Ponce, M.,Gomes, D.,Pereira Nunes, S. %D 2008 %J Journal of Membrane Science %N 1-2 %P 14-22 %R doi:10.1016/j.memsci.2008.03.031 %T One-pot synthesis of high molecular weight sulfonated poly(oxadiazole-triazole) copolymers for proton conductive membranes %U https://doi.org/10.1016/j.memsci.2008.03.031 1-2 %X For the first time, a series of high molecular weight (1–4 × 105 g mol−1) sulfonated poly(oxadiazole–triazole) copolymers have been synthesized at high temperatures and very short reaction time, by a single-step method based on solution polycondensation reaction of non-sulfonated dicarboxylic acid, hydrazine sulphate and aromatic primary amine (sulfonated and non-sulfonated) in poly(phosphoric acid). By this fast synthetic procedure, copolymers with a high conversion to triazole groups (up to 93%) as well high sulfonation level (IEC = 1.17–1.84 mequiv. g−1) have been obtained. The structure of the polymers was characterized by elemental analysis and 1H NMR.,Since high sulfonation levels (IEC = 1.17–1.84 mequiv. g−1) could be obtained, membranes were prepared from these polymers and have been characterized aiming the application in fuel cells. Proton conductivity up to 6 × 10−2 S cm−1 at 150 °C was measured. The polymer films had good mechanical properties with storage modulus of about 3 GPa at 300 °C. These films exhibited high thermal stability with Tg up to around 440 °C. %0 journal article %@ 0887-6266 %A Xu, P.,Xin, J.,Abetz, V.,Jiang, S.,Shen, J. %D 2008 %J Journal of Polymer Science B %N 19 %P 2047-2053 %R doi:10.1002/polb.21539 %T Tunable morphologies of rhenium complex-containing polystyrene-block-poly(2-vinylpyridine) aggregates %U https://doi.org/10.1002/polb.21539 19 %X Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer was functionalized with luminescent chlorotricarbonyl rhenium (I) phenanthroline complex in the presence of silver perchlorate. The copolymer-metal complex showed high sensitivity to the solvent system. Different morphologies and dimensions of the rhenium complex within nanosized micelles were controlled by changing the solvent systems. Core-embedded rhenium complex within micelles appear by adding methanol, a poor solvent for the copolymer-metal complex, to the solution of common solvent tetrahydrofuran (THF); the number of the core-embedded rhenium complex and the scale of the micelles are strongly related to the addition of methanol. Moreover, a novel morphology of corona-embedded rhenium complex micelles was prepared by dropping the original THF solution of copolymer-metal complex into water at a low pH value. %0 journal article %@ 0927-7757 %A Lutter, S.,Koetz, J.,Tiersch, B.,Boschetti de Fierro, A.,Abetz, V. %D 2008 %J Colloids and Surfaces A %N 3 %P 169-176 %R doi:10.1016/j.colsurfa.2008.07.014 %T Formation of gold nanoparticles in triblock terpolymer-modified inverse microemulsions %U https://doi.org/10.1016/j.colsurfa.2008.07.014 3 %X The influence of polystyrene (PS)-block–poly(1,4-butadiene) (PB)-block–poly(ethylene oxide) (PEO) and poly(1,4-butadiene)-block–polystyrene-block–poly(ethylene oxide) triblock terpolymers on the phase behaviour of the w/o microemulsion of the pseudo-ternary system made of water/sodium dodecylsulfate (SDS)/xylene–pentanol (1:1) was investigated by varying the sequence of the blocks. Independent on the terpolymer used an enlargement of L2 phase can be observed with increasing polymer concentration. Simultaneously, a decrease of the diameter of the mixed inverse terpolymer-surfactant micelles can be observed by dynamic light scattering. After cross-linking of the butadiene units, covalently closed nanocapsules with an average size between 20 and 30 nm can be observed.,When the triblock terpolymer-modified microemulsion is used as a template for the nanoparticle formation, gold nanoparticles with diameters of about 10 nm are formed. After solvent evaporation, the terpolymer-modified, hydrophobic gold nanoparticles can be redispersed in a toluene–pentanol mixture, and eliminated from the non-soluble surfactant residue. %0 journal article %@ 0032-3861 %A Alvarez-Gallego, Y.,Ruffmann, B.,Silva, V.,Silva, H.,Lozano, A.E.,de la Campa, J.G.,Pereira Nunes, S.,de Abajo, J. %D 2008 %J Polymer %N 18 %P 3875-3883 %R doi:10.1016/j.polymer.2008.06.048 %T Sulfonated polynaphthalimides with benzimidazole pendant groups %U https://doi.org/10.1016/j.polymer.2008.06.048 18 %X A series of new polyimides bearing simultaneously sulfonic acid groups and benzimidazole rings in different proportions have been synthesised by one pot high temperature polycondensation. The composition of the copolymers, as well as the distribution of the ionic sites along the polymer chain, has been changed systematically in order to study their relation with polymer properties. The incorporation of sulfonic side groups in the structure improves the solubility in polar organic solvents. In turn, the presence of sulfonic acid moieties impairs thermal resistance. Membranes based on the synthesised polyimides were prepared by solution casting and their water uptake as well as proton conductivity were determined. %0 journal article %@ 1582-9596 %A Nistor, C.,Shishatskiy, S.,Popa, M.,Pereira Nunes, S. %D 2008 %J Environmental Engineering and Management Journal %N 6 %P 653-659 %T Composite membranes with Cross-Linked Matrimid Selective Layer for Gas Separation %U 6 %X In the present work, composite membranes were developed for separation of hydrogen from its mixtures with other gases. The composite membranes were characterized by single gas permeation and scanning electron microscopy. Gas transport properties have been determined for four gases (H2, C~, N2, CO2). The influence of cross-linking on transport was measured. HiC~ selectivity values up to 115 were obtained. The resulting membranes have a selectivity ofH/C~ close to intrinsic selectivity of Matrimid 5218. %0 journal article %@ 1615-6846 %A Ponce, M.L.,Boaventura, M.,Gomes, D.,Mendes, A.,Madeira, L.M.,Pereira Nunes, S. %D 2008 %J Fuel Cells %N 3-4 %P 209-216 %R doi:10.1002/fuce.200800012 %T Proton Conducting Membranes Based on Benzimidazole Sulfonic Acid Doped Sulfonated Poly(Oxadiazole-Triazole) Copolymer for Low Humidity Operation %U https://doi.org/10.1002/fuce.200800012 3-4 %X This work reports for the first time the preparation of sulphonated poly(oxadiazole-triazole) copolymer membranes doped with amphoteric molecule, 1H-benzimidazole-2-sulphonic acid and their characterisation as proton conductors at 120 °C and low humidity. The membranes had not only high proton conductivities, up to 4 × 10-3 S cm-1 at 120 °C and low relative humidity (5 and 10%), but also had good mechanical properties with a storage modulus of about 3 GPa at 300 °C and high thermal stability with Tg up to around 420 °C. Because of their superior ion conducting and mechanical properties they have potential as a proton conducting membrane for fuel cell applications, in particular at high temperature and extremely low-humidity conditions. %0 journal article %@ 0376-7388 %A Gosalawit, R.,Chirachanchai, S.,Shishatskiy, S.,Pereira Nunes, S. %D 2008 %J Journal of Membrane Science %N 2 %P 337-346 %R doi:10.1016/j.memsci.2008.06.038 %T Sulfonated montmorillonite/sulfonated poly(ether ether ketone) (SMMT/SPEEK) nanocomposite membrane for direct methanol fuel cells (DMFCs) %U https://doi.org/10.1016/j.memsci.2008.06.038 2 %X A nanocomposite membrane of sulfonated montmorillonite/sulfonated poly(ether ether ketone) (SMMT/SPEEK) is proposed for direct methanol fuel cells (DMFCs). The SMMT is clay modified with silane of which the structure consists of a sulfonic acid group for proton conductivity improvement. The micro- and nano-scaled morphologies of the membranes perform the increase in inorganic aggregation with SMMT loading content as confirmed by SEM and AFM. The membrane stability, i.e., the liquid uptake in water and in methanol aqueous solution, as well as the mechanical stability increases with the SMMT loading content whereas thermal stability does not improve significantly. The methanol permeability reduction is obtained when the SMMT loading content increases for various methanol concentrations (1.5–4.5 M). A comparative study of the SPEEK nanocomposite membranes with SMMT and with pristine MMT shows fourfold proton conductivity enhancement after sulfonation. The DMFC single cell tests inform us that all nanocomposite membranes give the significant performance revealed by the plot of current density–voltage and power density. %0 journal article %@ 1022-1352 %A Boschetti de Fierro, A.,Lorenzo, A.T.,Mueller, A.J.,Schmalz, H.,Abetz, V. %D 2008 %J Macromolecular Chemistry and Physics %N 5 %P 476-487 %R doi:10.1002/macp.200700434 %T Crystallization Kinetics of PEO and PE in Different Triblock Terpolymers: Effect of Microdomain Geometry and Confinement %U https://doi.org/10.1002/macp.200700434 5 %X The isothermal crystallization kinetics of PEO and PE blocks within various triblock terpolymers were studied by DSC. The effect of the geometry of the microdomains was analyzed by studying different compositions of PE-b-PS-b-PEO triblock terpolymers. The crystallization rate decreased for decreasing block content for both crystallizable blocks. The effect of the microdomain geometry, confinement or chain tethering on the crystallization of PEO was extensively studied by comparing pairs of triblock terpolymers with differences either in the nature (crystalline, glassy, amorphous) or in the location of the other blocks in the terpolymer. %0 journal article %@ 1866-5217 %A Abetz, V. %D 2008 %J Labor & More %N 5 %P 40-41 %T Synthetische Membranen - Stofftrennung und selektiver Transport %U 5 %X Im Bereich polymerbasierter Membranmaterialien, die zur Stofftrennung und Katalyse,eingesetzt werden, stellen sich,eine Vielzahl interessanter wissenschaftlicher und technologischer Herausforderungen,,von denen diejenigen mit einer besonders hohen gesellschaftlichen Relevanz im Institut für Polymerforschung des GKSS,Forschungszentrum bearbeitet werden. %0 journal article %@ %A Ebert, K. %D 2008 %J Unter uns %N 3 %P 26 %T Nanofasern als Traegerstrukturen fuer Katalysatoren %U 3 %X %0 journal article %@ 0926-860X %A Ebert, K.,Bengtson, G.,Just, R.,Oehring, M.,Fritsch, D. %D 2008 %J Applied Catalysis A %N 1-2 %P 72-78 %R doi:10.1016/j.apcata.2008.05.009 %T Catalytically active poly(amideimide) nanofibre mats with high activity tested in the hydrogenation of methyl-cis-9-octadecenoate %U https://doi.org/10.1016/j.apcata.2008.05.009 1-2 %X Nanofibres of poly(amideimide) (PAI) were prepared by electrospinning from solutions of 11 wt% PAI in dimethylformamide. Addition of small amounts of citric acid to the spinning solution improved the fibre size and fibre uniformity. Catalytic activation of the electrospun nanofibres was performed by coating the fibres with an organic solution of palladium diacetate containing citric acid onto the fibres and subsequent thermally induced conversion to nanosized palladium clusters. The catalyst was durably fixed on the fibres by this procedure. The presence of palladium (Pd) nanoparticles was confirmed by R-ray-diffractometry. These fibres were applied in the hydrogenation of methyl-cis-9-octadecenoate as a model reaction. The palladium-doped nanofibres showed an almost seven times higher hydrogenation rate than a commercial palladium catalyst supported on alumina. %0 journal article %@ 0376-7388 %A Gomes, D.,Marschall, R.,Pereira Nunes, S.,Wark, M. %D 2008 %J Journal of Membrane Science %N 2 %P 406-415 %R doi:10.1016/j.memsci.2008.06.010 %T Development of polyoxadiazole nanocomposites for high temperature polymer electrolyte membrane fuel cells %U https://doi.org/10.1016/j.memsci.2008.06.010 2 %X Novel nanocomposite membranes were prepared with sulfonated polyoxadiazole and different amounts of sulfonated dense and mesoporous (MCM-41) silica particles. It has been shown that particle size and functionality of sulfonated silica particles play an important role when they are used as fillers for the development of polymer electrolyte nanocomposite membrane for fuel cells. No significant particle agglomerates were observed in all nanocomposite membranes prepared with sulfonated dense silica particles, as analyzed by SEM, AFM, TGA, DMTA and tensile tests. The Tg values of the composite membranes increased with addition of sulfonated silica, indicating an interaction between the sulfonic acid groups of the silica and the polyoxadiazole. Constrained polymer chains in the vicinity of the inorganic particles were confirmed by the reduction of the relative peak height of tan δ. A proton conductivity of 0.034 S cm−1 at 120 °C and 25% RH, which is around two-fold higher than the value of the pristine polymer membrane was obtained. %0 journal article %@ 0376-7388 %A Budd, P.,McKeown, N.,Ghanem, B.,Msayib, K.,Fritsch, D.,Starannikova, L.,Belov, N.,Sanfirova, O.,Yampolskii, Y.,Shantarovich, V. %D 2008 %J Journal of Membrane Science %N 2 %P 851-860 %R doi:10.1016/j.memsci.2008.09.010 %T Gas permeation parameters and other physicochemical properties of a polymer of intrinsic microporosity: Polybenzodioxane PIM-1 %U https://doi.org/10.1016/j.memsci.2008.09.010 2 %X A detailed study of gas permeation, thermodynamic properties and free volume was performed for a novel polymer of intrinsic microporosity (PIM-1). Gas permeability was measured using both gas chromatographic and barometric methods. Sorption of vapors was studied by means of inverse gas chromatography (IGC). In addition, positron annihilation lifetime spectroscopy (PALS) was employed for investigation of free volume in this polymer. An unusual property of PIM-1 is a very strong sensitivity of gas permeability and free volume to the film casting protocol. Contact with water in the process of film preparation resulted in relatively low gas permeability (P(O2) = 120 Barrer), while soaking with methanol led to a strong increase in gas permeability (P(O2) = 1600 Barrer) with virtually no evidence of fast aging (decrease in permeability) that is typical for highly permeable polymers. For various gas pairs (O2/N2, CO2/CH4, CO2/N2) the data points on the Robeson diagrams are located above the upper bound lines. Hence, a very attractive combination of permeability and selectivity is observed. IGC indicated that this polymer is distinguished by the largest solubility coefficients among all the polymers so far studied. Free volume of PIM-1 includes relatively large microcavities (R = 5 Å), and the results of the PALS and IGC methods are in reasonable agreement. %0 journal article %@ 0024-9297 %A Boschetti de Fierro, A.,Mueller, A.,Abetz, V. %D 2007 %J Macromolecules %N 4 %P 1290-1298 %R doi:10.1021/ma0625713 %T Synthesis and characterization of novel linear PB-b-PS-b-PEO and PE-b-PS-b-PEO triblock terpolymers %U https://doi.org/10.1021/ma0625713 4 %X Novel polybutadiene-block-polystyrene-block-poly(ethylene oxide) (PB-b-PS-b-PEO) linear triblock terpolymers have been synthesized by sequential living anionic polymerization. Further catalytic hydrogenation led to polyethylene-block-polystyrene-block-poly(ethylene oxide) (PE-b-PS-b-PEO), a triblock terpolymer with two crystallizable blocks and a glassy middle block. Bulk morphologies have been studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) for different compositions. Thermal properties of,the PEO block, as determined by differential scanning calorimetry (DSC), showed dependence with the block volume fraction (PEO) and its polymerization degree (NPEO). The corresponding properties for the PE block are also functions of the polymerization degree (NPE) and the volume fraction of the PEO block (PEO). Since the PEO block is the first to segregate from solution in toluene, its volume fraction determines the overall morphology,and consequently the thermal properties of the studied terpolymers. %0 journal article %@ 0376-7388 %A Bengtson, G.,Panek, D.,Fritsch, D. %D 2007 %J Journal of Membrane Science %N 1-2 %P 29-35 %R doi:10.1016/j.memsci.2007.01.031 %T Hydrogenation of acetophenone in a pervaporative catalytic membrane reactor with online mass spectrometric monitoring %U https://doi.org/10.1016/j.memsci.2007.01.031 1-2 %X A pervaporative catalytic membrane reactor can afford chemical reaction and separation or concentration of the products in one step. The hydrogenation of acetophenone (AP) in diluted aqueous solution was investigated applying catalytically reactive polydimethylsiloxane,(PDMS) and polyether-b-amide (PEBA) membranes in the pervaporative membrane reactor.,A quadrupole mass spectrometer (QMS) was employed to follow online the hydrogenation reaction. Homogeneously distributed palladium clusters inside the polymeric membranes catalyze the hydrogenation of AP to 2-phenylethanol (PE) and the consecutive product ethyl benzene (EB) at low temperatures (30-70°C). The reaction depends strongly on the,disposability of H2 inside the membrane. Only by means of the online QMS analyser the availability of stoichiometric or excess amounts of H2 at the catalyst with adjusted parameters such as temperature, hydrogen pressure, solute concentrations and membrane permeability could be detected. It could be shown, that the hydrogen level by bubbling at ambient pressure,was not sufficient, however, at 4 bar H2 pressure and 50°C conversions up to 83% in 6h were obtained. Efforts to quantify the measured intensities of the QMS were not successful;,however, the relation of the organic compounds and the presence of excess H2 were detected precisely with this method. %0 journal article %@ 1022-1352 %A Roeder, J.,Gomes, D.,Ponce, M.L.,Abetz, V.,Pereira Nunes, S. %D 2007 %J Macromolecular Chemistry and Physics %N %P 467-473 %R doi:10.1002/macp.200600515 %T Protonation of Sulfonated Poly(4,4’-diphenylether-1,3,4-oxadiazole) Membranes %U https://doi.org/10.1002/macp.200600515 %X This work describes the effect of sulfuric acid protonation on the properties of SPOD-DPE membranes using FT-IR and impedance spectroscopic analyses. The IR spectra showed the protonation of nitrogen atoms from oxadiazole rings, with a broad band complex in the region 3 000–2 100 cm1 with two centered peaks at 2 590 and 2 440 cm1. The S––O characteristic,absorption bands in SPOD-DPE and sulfuric acid were specially studied in the region of 1 800–900 cm1. The,band shifts are associated to the interaction between acid groups and oxadiazole ring nitrogen atoms. The IR spectra evidenced the presence of three absorption species (HSO4, SO2 4 and free H2SO4) depending on the sulfuric acid concentration. For the protonated SPOD-DPE membranes, a proton conductivity around 10 mScm1 was reached at 50 8C. %0 journal article %@ 1022-1336 %A Alvarez-Gallego, Y.,Pereira Nunes, S.,Lozano, A.E.,de la Campa, J.G.,de Abajo, J. %D 2007 %J Macromolecular Rapid Communications %N 5 %P 616-622 %R doi:10.1002/marc.200600700 %T Synthesis and Properties of Novel Polyimides Bearing Sulfonated Benzimidazole Pendant Groups %U https://doi.org/10.1002/marc.200600700 5 %X A new diamine monomer containing benzimidazole-5-sulfonic acid has been synthesised. It has been reacted, alone or mixed with diaminodiphenyl ether, with naphthalenic dianhydride to attain polynaphthalimides in which the sulfonic acid functionality is borne by pendant benzimidazole groups. The presence of sulfonic and benzimidazole groups greatly affected the physical properties of the polyimides as the novel polymers were found to be soluble in polar organic solvents and exhibited a lower thermal resistance than their non-sulfonated counterparts. The polymer films exhibited good mechanical properties with tensile strength in the range 100-120 MPa and with moduli in the range 2.2-3.1 GPa. Sulfonic and benzimidazole groups significantly enhanced the hydrophilicity of the copolyimides, which showed water uptake up to 39%. %0 journal article %@ 1022-1360 %A Budd, P.M.,McKeown, N.B.,Fritsch, D. %D 2007 %J Macromolecular Symposia %N 1 %P 403-405 %R doi:10.1002/masy.200651356 %T Polymers of Intrinsic Microporosity (PIMs): High Free Volume Polymers for Membrane Applications %U https://doi.org/10.1002/masy.200651356 1 %X We are developing new types of polymer - termed polymers of intrinsic microporosity (PIMs) - which in the solid state behave like molecular sieves. As pervaporation membranes, they show selectivity for organics over water. As gas separation membranes, they exhibit a remarkable combination of high permeability and good selectivity for gas pairs such as O2/N2. %0 journal article %@ 0024-9297 %A Lorenzo, A.T.,Arnal, M.L.,Mueller, A.J.,Boschetti de Fierro, A.,Abetz, V. %D 2007 %J Macromolecules %N 14 %P 5023-5037 %R doi:10.1021/ma070252l %T Nucleation and Isothermal Crystallization of the Polyethylene Block within Diblock Copolymers Containing Polystyrene and Poly(ethylene-alt-propylene) %U https://doi.org/10.1021/ma070252l 14 %X The crystallization kinetics of the polyethylene block within polyethylene-b-polystyrene (PE-b-PS) and polyethylene-b-poly(ethylene-alt-propylene) (PE-b-PEP) diblock copolymers has been investigated in a wide composition range by differential scanning calorimetry (DSC) and compared to an equivalent homopolymer. The morphology of the copolymers in the melt and its changes after crystallization were explored by small-angle X-ray scattering (SAXS) experiments. SAXS experiments demonstrated that PE-b-PS formed microdomain ordered structures in the melt. On the basis of the lamellar morphology that was developed by PE-b-PEP (demonstrated by transmission electron microscopy, TEM) regardless of composition, it was deduced that these diblocks crystallize from either a homogeneous or a weakly segregated melt. Also, the effects of the neighboring block on thermal fractionation of the PE block were obtained by successive self-nucleation and annealing (SSA). Classical kinetics theories of polymer nucleation and crystallization were applied to DSC overall isothermal crystallization data. The energetic parameters obtained allow us to quantitatively estimate the increase in the energy barrier for crystallization of the PE block, caused by the covalently bonded PEP and PS block as compared to homo-PE. Also, the Lauritzen and Hoffman theory was applied to DSC isothermal crystallization of previously self-nucleated PE (where crystal growth is the dominant factor), and the contributions of nucleation and growth were estimated. Using this novel approach, we demonstrate that the nucleation process is the rate-determining step in the crystallization behavior of highly confined PE-b-PS diblock copolymers, results that were corroborated by the low Avrami index values found in these diblock copolymers. Similar trends were obtained by applying polymer nucleation theories. In the case of PE-b-PEP diblock copolymers, the energy barrier associated with nucleation and growth increases as the PEP content within the copolymers increases. The PEP block acts as a diluent for the PE block crystallization in view of the miscibility between the blocks. %0 journal article %@ 0888-5885 %A Brandao, L.,Fritsch, D.,Mendes, A.M.,Madeira, L.M. %D 2007 %J Industrial & Engineering Chemistry Research %N 2 %P 377-384 %R doi:10.1021/ie0602761 %T Propyne Hydrogenation Kinetics over Surfactant-Stabilized Palladium Nanoclusters %U https://doi.org/10.1021/ie0602761 2 %X The kinetics of propyne hydrogenation over surfactant-stabilized palladium nanoclusters was studied in a batch reactor under isothermal conditions (308 K). The method of initial rates was adopted to elucidate the reaction mechanism and a rate equation was derived. Although the methodology employed does not exclude other reaction schemes, it was found that experimental rate data agree well with a Langmuir-Hinshelwood mechanism that involves noncompetitive adsorption between propyne and hydrogen for the catalyst surface, where hydrogen addition in the surface reaction(s) is the limiting step. Nonlinear model fitting to initial rate data provided the kinetic parameters of the rate equation (k (mol·gPd-1·s-1·bar-2) = 4.1; KC3H4 (bar-1) = 8.7 × 102; and KH2 (bar-1) = 1.0 × 10-5). Finally, experimental compositions of the reaction mixture over time, as well as the overall advancement history, were compared favorably with the kinetic model through integration of the mass balance in the batch reactor. %0 journal article %@ 0032-3861 %A Ruckdaeschel, H.,Sandler, J.K.W.,Altstaedt, V.,Schmalz, H.,Abetz, V.,Mueller, A.H.E. %D 2007 %J Polymer %N 9 %P 2700-2719 %R doi:10.1016/j.polymer.2007.03.005 %T Toughening of immiscible PPE/SAN blends by triblock terpolymers %U https://doi.org/10.1016/j.polymer.2007.03.005 9 %X The mechanical performance of immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-co-acrylonitrile) (SAN) and the subsequent influence of compatibilisation by tailored,polystyrene-block-polybutadiene-block-poly(methyl methacrylate) triblock terpolymers (SBM) on the,mechanical performance under static and dynamic loads is analysed in detail. A PPE/SAN 60/40 blend was,selected as a base system for the compatibilisation experiments. The observed static tensile behaviour is,described by micromechanical models and correlated to the blend microstructures as observed by,transmission electron microscopy. In most cases, the addition of the SBM triblock terpolymers further,enhances the ductility of the blend while only leading to a minor reduction of modulus and strength. Triblock terpolymers with symmetric end blocks, mainly located at the interface between PPE and SAN, led to nearly isotropic specimens. In contrast, SBM materials with a longer polystyrene block predominantly formed,micelles in the PPE phase and the blends revealed a highly anisotropic morphology. Comparative,investigations of the fatigue crack growth behaviour parallel to the direction of injection also reflected this variation in mechanical anisotropy of the compatibilised blends. A poor toughness and a predominant interfacial failure were observed in the case of the SBM with a long polystyrene block. In contrast, a considerable improvement in properties as a result of pronounced plastic deformations was observed for blends compatibilised by triblock terpolymers with symmetric end blocks. The systematic correlation,between morphology and mechanical performance of compatibilised PPE/SAN blends established in this,study provides an efficient way for the desired selection of suitable and effective compatibilising agents,,ensuring both a superior multiaxial toughness as well as a high strength and modulus of the overall system. %0 journal article %@ 1550-6703 %A Walther, A.,Andre, X.,Drechsler, M.,Abetz, V.,Mueller, A.H.E. %D 2007 %J PMSE Preprints %N %P 86-87 %T Janus discs: preparation, size-tunability, visualization, self-assembly %U %X In recent years, Janus particles have attracted much attention in,nanoscience due to their interesting properties, both for academic as,well as for technological reasons. In general, Janus structures have a,compartmentalized surface and can be divided into three classes according to their architecture – spherical Janus micelles (3D)1, 2, two types of Janus cylinders (1D)3 and Janus sheets or discs (2D), representing the intermediate case of dimensionality (see scheme 1). The,synthesis of such non-centrosymmetric structures with compartmentalized coronas is a demanding task for the synthetic chemist. Hence, only a few real nanosized polymer-based Janus structures are known in literature. %0 journal article %@ 0376-7388 %A Gomes, D.,Roeder, J.,Ponce, M.L.,Pereira Nunes, S. %D 2007 %J Journal of Membrane Science %N 1-2 %P 121-129 %R doi:10.1016/j.memsci.2007.02.046 %T Characterization of Partially Sulfonated Polyoxadiazoles and Oxadiazole-triazole Copolymers %U https://doi.org/10.1016/j.memsci.2007.02.046 1-2 %X Experimental evidences regarding the sulfonation of polyoxadiazole and oxadiazole–triazole copolymers during the preparation are given. The structures of the polymers were qualitatively and quantitatively characterized by elemental analysis, 1H NMR, and FTIR. Polymers with high molecular weights (up to 470,000 g/mol) exhibiting highly oxidative stability are obtained allowing the casting of mechanically stable membranes with high storage modulus (about 4 GPa at 100 °C) and high proton conductivity values (order of magnitude of 10−2 S cm−1 at 80 °C). %0 journal article %@ 1022-1336 %A Diaz, A.M.,Zolotukhin, M.G.,fomine, S.,Salcedo, R.,Manero, O.,Cedillo, G.,Velasco, V.M.,Guzman, M.T.,Fritsch, D.,Khalizov, A.F. %D 2007 %J Macromolecular Rapid Communications %N 2 %P 183-187 %R doi:10.1002/marc.200600656 %T A Novel, One-Pot Synthesis of Novel 3F, 5F, and 8F Aromatic Polymers %U https://doi.org/10.1002/marc.200600656 2 %X A series of novel, linear, soluble, high-molecular-weight, fluorinated aromatic polymers has been obtained for the first time using a superacid-catalyzed polyhydroxyalkylation reaction of fluorinated carbonyl-containing compounds: 1,1,1,-trifluoroacetone (1), 2,2,2-trifluoroacetophenone (2), 2,3,4,5,6,-pentafluorobenzaldehyde,(3), and octafluoroacetophenone (4) with aromatic hydrocarbons such as biphenyl (a), phenyl ether (b), terphenyl (c), and 4,40-diphenoxybenzophenone (d). These Friedel-Crafts-type aromatic electrophilic substitution reactions are performed at room temperature in trifluoromethane sulfonic acid or in its mixtures with dichloromethane. The polymers obtained are soluble in common organic solvents, and colorless transparent films could be cast from the solutions. 1H and 13C NMR analyses of the polymers synthesized reveal their linear, highly regular structure. The polymers also possess high thermostability. %0 journal article %@ 0002-7863 %A Walther, A.,Andre, X.,Drechsler, M.,Abetz, V.,Mueller, A.H.E. %D 2007 %J Journal of the American Chemical Society %N 19 %P 6187-6198 %R doi:10.1021/ja068153v %T Janus Discs %U https://doi.org/10.1021/ja068153v 19 %X We describe the synthesis and the solution properties of sheet- and disclike Janus particles, containing an inner crosslinked polybutadiene (PB) layer and two different outer sides of polystyrene (PS) and poly(tert-butyl methacrylate) (PtBMA). The structures formed upon adsorption of the flat Janus particles onto solid substrates as well as in THF solution are investigated. The Janus discs are obtained in a template-assisted synthetic pathway followed by sonication. Selectively crosslinking the lamellar PB domains in a well-ordered lamellar microphase-separated bulk morphology of PS-block-PB-block-PtBMA (SBT) block terpolymers leads to the conservation of the compartmentalization of the two outer blocks. Sonication of the crosslinked block terpolymer templates renders soluble sheet- and disclike Janus particles, the size of which can be tuned from the micrometer range down to the nanometer scale. Small-angle X-ray scattering, transmission electron microscopy, dynamic light scattering, scanning force microscopy, and scanning electron microscopy are used to characterize the template-assisted synthetic process and the solution properties. Cryogenic transmission electron microscopy in THF and TEM of particles, embedded into a photo-crosslinkable silicon oil, indicate a supramolecular aggregation behavior of the Janus discs in concentrated solutions. Pendant drop tensiometry demonstrates that Janus sheets and discs can be used to stabilize liquid-liquid interfaces, rendering these materials interesting for future applications. %0 journal article %@ 0021-9797 %A Lutter, S.,Tiersch, B.,Koetz, J.,Boschetti de Fierro, A.,Abetz, V. %D 2007 %J Journal of Colloid and Interface Science %N 2 %P 447-455 %R doi:10.1016/j.jcis.2007.03.034 %T Covalently closed microemulsions in presence of triblock terpolymers %U https://doi.org/10.1016/j.jcis.2007.03.034 2 %X This paper is focused on the influence of polystyrene (PS)–poly(1,4-butadiene) (PB)–poly(ethylene oxide) (PEO) triblock terpolymers on the w/o microemulsion of the pseudo-ternary system water/sodium dodecylsulfate (SDS)/xylene-pentanol. Despite the insolubility of the copolymer in water as well as in the xylene–pentanol mixture, it can be incorporated into the w/o microemulsion and interactions between the triblock terpolymer,molecules and the anionic surfactant headgroups can be detected by differential scanning calorimetry (DSC) measurements. Furthermore, dynamic light scattering measurements were used to determine the aggregate diameter of the modified microemulsions. For lower polymer concentrations large aggregates between 100 and 500 nm can be observed. Surprisingly, at a higher terpolymer concentration of 5 wt%, significant smaller aggregate diameters can be identified by dynamic light scattering and Cryo-SEM. One can conclude that the copolymers are incorporated in the,inverse microemulsion droplets, where the PB blocks cover the water droplets. The thermally induced radical cross-linking of the butadiene units in the presence of azobisisobutyronitrile (AIBN) leads then to covalently closed nanocapsules with an average size of 10 nm. %0 journal article %@ 0032-3934 %A Spontak, R.J.,weaver, J.T.,Gozen, A.O.,Abetz, V.,Smith, S.D.,Genzer, J.,Agard, D.A. %D 2007 %J Polymer Preprints %N 2 %P 507-508 %T Transmission electron microtomography of multicomponent block copolymer systems %U 2 %X Transmission electron microtomog. (TEMT) is a rapidly growing anal. technique that holds tremendous promise for providing valuable insight into polymeric nanostructures, esp. those that are geometrically complex or that evolve with time or environmental conditions. The approach adopted here is based on single-tilt tomog. in conjunction with filtered back projection. In this work, we report on several different multicomponent block copolymer morphologies that have been recently investigated by TEMT. Using cryogenic imaging conditions, one study addresses the dispersed morphologies of block copolymers in the presence of solvent. Another series explores blends of ABC triblock copolymers, while a third seeks to elucidate the behavior of block copolymer mols. in the presence of other network-forming additives. Lastly, we demonstrate how TEMT can be used to discern the mechanism by which block copolymer self-assembly proceeds in a highly nonequil., dynamically evolving thin-film environment. %0 journal article %@ 0024-9297 %A Boschetti de Fierro, A.,Spindler, L.,Reiter, G.,Olmos, D.,Magonov, S.,Abetz, V. %D 2007 %J Macromolecules %N 15 %P 5487-5496 %R doi:10.1021/ma0703812 %T Thin Film Morphology in Triblock Terpolymers with One and Two Crystallizable Blocks %U https://doi.org/10.1021/ma0703812 15 %X The thin film morphology of novel polybutadiene-block-polystyrene-block-poly(ethylene oxide) (PB-b-PS-b-PEO) and polyethylene-block-polystyrene-block-poly(ethylene oxide) (PE-b-PS-b-PEO) triblock terpolymers was determined by atomic force microscopy. The experiments were carried out on dry, wet, and heated samples in order to vary the contrast among the blocks. The different measurements allowed the discrimination between the PE and the PEO blocks, which was otherwise not possible. The effect of different thermal treatments (related to the crystallization temperatures) on the generated morphology was studied for a confined spherical morphology. The domain size, i.e., disk diameter, was found to increase as the crystallization temperature was increased. %0 journal article %@ 1022-1352 %A Yave, W.,Shishatskiy, S.,Abetz, V.,Matson, S.,Litvinova, E.,Khotimskiy, V.,Peinemann, K.-V. %D 2007 %J Macromolecular Chemistry and Physics %N 22 %P 2412-2418 %R doi:10.1002/macp.200700399 %T A Novel Poly(4-methyl-2-pentyne)/TiO2 Hybrid Nanocomposite Membrane for Natural Gas Conditioning: Butane/Methane Separation %U https://doi.org/10.1002/macp.200700399 22 %X Poly(4-methyl-2-pentyne) (PMP)/TiO2 hybrid nanocomposite membranes have been investigated for natural gas conditioning. Tailor-made PMP with 35% cis-content was identified as an attractive material to prepare nanocomposite membranes; it presented good stability towards organic vapors and optimal properties for butane/methane separation. The PMP/TiO2 hybrid nanocomposite membranes presented an improvement of butane permeability and butane/methane selectivity. The addition of TiO2 nanoparticles to the PMP enhanced the selectivity more effectively than fumed-silica, and it is attractively higher than those currently reported in the open literature. %0 journal article %@ 0167-2738 %A Gosalawit, R.,Chirachanchai, S.,Shishatskiy, S.,Pereira Nunes, S. %D 2007 %J Solid State Ionics %N 29-30 %P 1627-1635 %R doi:10.1016/j.ssi.2007.10.008 %T Krytox-Montmorillonite-Nafion nanocomposite membrane for effective methanol crossover reduction in DMFCs %U https://doi.org/10.1016/j.ssi.2007.10.008 29-30 %X Nafion® and Montmorillonite (MMT) functionalized with Krytox nanocomposite membrane (Krytox–MMT–Nafion®) is proposed for DMFC applications. The nanocomposite is obtained with good compatibility between MMT and Nafion® via the function of Nafion®-like polymer chain namely Krytox 157 FSL. The MMT layers are exfoliated with Nafion® polymer matrices and show homogeneity as confirmed by XRD and SEM. The AFM micrographs clarifies the successful MMT clay dispersion all over the nanocomposite membrane. The thermogravimetric analysis exhibits the improvement in water retention and thermal resistance as compared to Nafion® membrane. The membranes perform for more than 50% reduction in the permeation of methanol in 10%(v/v) solution at either room temperature or as high as 60 °C. The Arrhenius plot suggests the lower activation energy for proton migration in the Krytox–MMT–Nafion® membranes than in the Nafion® membrane under Grotthus mechanism. %0 journal article %@ 1550-6703 %A Budd, P.M.,Selbie, J.D.,Awal, M.A.,McKeown, N.B.,Ghanem, B.S.,Msayib, K.J.,Fritsch, D. %D 2007 %J PMSE Preprints %N %P 276-277 %T Intrinsic Microporosity in Polyimides %U %X Polymers with molecular structures that cannot pack efficiently in the solid state and therefore trap a large amount of free volume may be regarded as having “intrinsic microporosity” (effective pore dimensions <2 nm). Polymers of intrinsic microporosity (PIMs) typically have rigid backbones (e.g., ladder-like sequences) and incorporate sites of contortion (e.g., spiro-centers) that force the backbone to twist and turn. Here we describe a novel polyimide that incorporates features of a PIM. We also demonstrate that other polyimides that exhibit very high permeability to gases may be regarded as “intrinsically microporous”. %0 journal article %@ 0151-9107 %A Pereira Nunes, S. %D 2007 %J Annales de Chimie - Science des Matériaux %N 2 %P 119-126 %R doi:10.3166/acsm.32.119-126 %T Organic-inorganic membranes for gas separation %U https://doi.org/10.3166/acsm.32.119-126 2 %X The recent developments of organic-inorganic materials applied for gas separation membranes are reviewed. The fundamentals of permeation in mixed matrix membranes are summarized, extending the examples to systems that do not follow the Maxwell equation. The advantages of organic-inorganic polymer networks for membranes are discussed. Some new promising systems including nanocomposites with block copolymers, metal-organic frameworks and carbon fillers with different geometries are presented. %0 journal article %@ 0149-6395 %A Silva, V.,Silva, V.B.,Mendes, A.,Madeira, L.,Silva, H.,Michaelmann, J.,Ruffmann, B.,Pereira Nunes, S. %D 2007 %J Separation Science and Technology %N SI 13 %P 2909-2925 %R doi:10.1080/01496390701558342 %T Pre-treatment Effect on the Sulfonated Poly(ether ether ketone) Membrane Transport Properties and Direct Methanol Fuel Cell Performance %U https://doi.org/10.1080/01496390701558342 SI 13 %X In this paper a critical study is presented on how the direct methanol fuel cell (DMFC) membrane properties are affected by a pre-treatment. Membranes based on sulfonated poly(ether ether ketone) (sPEEK) with sulfonation degree (SD) of 42% were used, plain and modified inorganically with 1 wt.% of zirconium oxide. Nafion® 1135 was used as reference. The results obtained show that the sPEEK polymer (SD=42%) enables the preparation of proton exchange membranes with improved properties compared to Nafion® and to the ZrO2-modified sPEEK membrane, mainly due to its improved relation between proton conductivity and methanol permeation. After the pre-treatment, the plain sPEEK membrane had a performance 6.4 times higher in terms of maximum power output when used in the DMFC. %0 journal article %@ 0024-9297 %A Yave, W.,Peinemann, K.-V.,Shishatskiy, S.,Khotimskiy, V.,Chirkova, M.,Matson, S.,Litvinova, E.,Lecerf, N. %D 2007 %J Macromolecules %N 25 %P 8991-8998 %R doi:10.1021/ma0714518 %T Synthesis, Characterization, and Membrane Properties of Poly(1-trimethylgermyl-1-propyne) and Its Nanocomposite with TiO2 %U https://doi.org/10.1021/ma0714518 25 %X The relationship between poly(1-trimethylgermyl-1-propyne) (PTMGP) microstructure and gas permeability property is reported. Controlling the synthesis conditions via TaCl5 and NbCl5 catalyst systems, tailor-made polyacetylenes in a wide range of cis/trans ratio (trans content from 35 to ~100%) were obtained. According to the cis and trans ratio in the polymeric chain, a two-phase structure was found characterized by the presence of regions with enhanced level of macrochains ordering and with amorphous regions. The polymer microstructure has been related with free-volume, gas permeability, and polymer resistance toward liquid hydrocarbons. PTMGP membranes with high trans content (80-90%) exhibited higher gas permeability than samples with low trans content. Gas permeability of PTMGP membranes decreased with the density of polymer films, i.e., with the free-volume fraction in polymers with different microstructures. Furthermore, it was demonstrated that gas permeability and resistance toward solvents of the PTMGPs are directly defined by their cis/trans microstructure and supramolecular ordering. PTMGP with well-defined microstructure (trans content between 80 and 90%) can be considered as potential membrane material for gas separation, e.g., separation of higher hydrocarbons from natural gas. PTMGP/TiO2 nanocomposite membranes were also studied for exploring the gas permeability properties and stability of polyacetylene membranes. Gas transport properties were affected slightly by TiO2 presence; however, the long-term stability was enhanced. %0 journal article %@ 0954-0083 %A Zolotukhin, M.G.,Fomine, S.,Lazo, L.M.,Gutierrez Hernandez, M.del C.G.,Guzman-Gutierrez, M.T.,Ruiz-Trevino, A.,Fritsch, D.,Cuellas, D.C.,Fernandez-G, J.M. %D 2007 %J High Performance Polymers %N 5 %P 638-648 %R doi:10.1177/0954008307081204 %T A Novel Approach to the Synthesis of High Performance and Functional Polymers %U https://doi.org/10.1177/0954008307081204 5 %X A novel series of linear, high molecular weight high performance and functional polymers were synthesized by a one-pot, superacid-catalyzed polyhydroxylakylation reaction of carbonyl compounds containing electron-withdrawing substituents, adjacent or relatively close to a carbocation center with non-activated aromatic hydrocarbons. The reactions were performed at room temperature in the Brønsted superacid CF3SO3H (trifluoromethanesulfonic acid, TFSA) and in a mixture of TFSA with methylene chloride, which was used as both solvent and a medium for generation of electrophilic species from the carbonyl component. Polycondensations of 1,1,1-trifluoroacetone, 2,2,2-trifluoroacetohenone, 2,7-dinitrofluorenone, acenaphthenequinone and isatin with aromatic hydrocarbons proceed readily in the presence of superacid at room temperature. The polymers obtained were found to be soluble in the common organic solvents, and flexible transparent films could be cast from the solutions. 1H and 13C NMR analyses of the polymers synthesized revealed their linear, highly regular structure. The polymers also possess high thermostability. %0 journal article %@ 0887-6266 %A Boschetti de Fierro, A.,Fierro, D.,Albuerne, J.,Funari, S.S.,Abetz, V. %D 2007 %J Journal of Polymer Science B %N 23 %P 3197-3206 %R doi:10.1002/polb.21318 %T Thermal Monitoring of Morphology in Triblock Terpolymers with Crystallizable Blocks %U https://doi.org/10.1002/polb.21318 23 %X The bulk morphology of poly(1,4-butadiene)-block-polystyrene-block-poly (ethylene oxide) (PB-b-PS-b-PEO) and polyethylene-block-polystyrene-block-poly (ethylene oxide) (PE-b-PS-b-PEO) triblock terpolymers is analyzed under a thermal protocol. This allows the investigation of the morphology during the occurrence of thermal transitions, such as crystallization and melting, which is a neat way of studying the competition between microphase separation and crystallization for the morphology formation. Only one of the studied systems presented a morphological transition upon melting of the PEO and the PE blocks, attributed to the crystallization of the PE block in finite interconnected domains. All the other systems presented no morphological transitions during the thermal scan. The results prove that the crystallization only disrupt the microphases generated in the molten state under very specific circumstances for these block copolymers. %0 journal article %@ 1476-1122 %A Peinemann, K.-V.,Abetz, V.,Simon, P. %D 2007 %J Nature Materials %N %P 992-996 %R doi:10.1038/nmat2038 %T Asymmetric superstructure in a block copolymer via phase separation %U https://doi.org/10.1038/nmat2038 %X Self-assembly of amphiphilic block copolymers into well-ordered structures has attracted significant interest over the past decade. An especially attractive application of block-copolymer self-assembly is the formation of isoporous membranes. A major problem in this process is the lack of sufficient long-range order and the difficulty of up-scaling due to the time-consuming preparation steps. Here, we report an innovative and simple method to prepare isoporous membranes with nanometre-sized pores. The combination of the industrially well-established membrane formation method by non-solvent-induced phase separation with the self-assembly of a block copolymer is demonstrated. The result is the creation of an integral asymmetric membrane of a block copolymer with a highly ordered thin layer on top of a non-ordered sponge-like layer. This straightforward and very fast one-step procedure for membrane formation is reported for the first time. The developed membrane has the potential for highly selective separation. %0 journal article %@ 1862-6254 %A de Miranda, R.L.,Kruse, J.,Raetzke, K.,Faupel, F.,Fritsch, D.,Abetz, V.,Budd, P.M.,Selbie, J.D.,McKeown, N.B.,Ghanem, B.S. %D 2007 %J Physica Status Solidi / Rapid Research Letters %N 5 %P 190-192 %R doi:10.1002/pssr.200701116 %T Unusual temperature dependence of the positron lifetime in a polymer of intrinsic microporosity %U https://doi.org/10.1002/pssr.200701116 5 %X The performance of polymeric membranes for gas separation is mainly determined by the free volume. Polymers of intrinsic microporosity are interesting due to the high abundance of accessible free volume. We performed measurements of the temperature dependence of the positron lifetime, generally accepted for investigation of free volume, in two polymers of intrinsic microporosity (PIM-1 and PIM-7) in the range from 143 to 523 K. The mean value of the free volume calculated from the ortho-positronium lifetime is in the range of typical values for high free volume polymers. However, the temperature dependence of the local free volume is non-monotonous in contrast to the macroscopic thermal expansion. The explanation is linked to the spirocenters in the polymer. %0 journal article %@ 0888-5885 %A Brandao, L.,Fritsch, D.,Mendes, A.M.,Madeira, L.M. %D 2007 %J Industrial & Engineering Chemistry Research %N 16 %P 5278-5285 %R doi:10.1021/ie0614879 %T Propylene hydrogenation in a continuous polymeric catalytic membrane reactor %U https://doi.org/10.1021/ie0614879 16 %X A continuous polymeric catalytic membrane reactor (pCMR), using a poly-(dimethylsiloxane) (PDMS),composite membrane that contained palladium nanoclusters, was studied and modeled for the propylene,hydrogenation. The PDMS catalytic membrane has an average thickness of 4.4 ím, and was loaded with 5 wt % of nanosized palladium clusters 9 nm in diameter. The reaction was performed at 308 K, and several feed compositions and flow rates were tested. The pCMR model proposed represents the experimental data (i.e., the flow rates and mixture compositions in the permeate and retentate chambers, and, therefore,,the overall advancement) fairly well. In the hydrogenation rate equation, the propylene adsorption parameter and the kinetic constant were obtained by fitting the model to the experimental data. On the other,hand, the hydrogen kinetic parameter and the mass-transport parameters were obtained from independent experiments. %0 journal article %@ 1438-1656 %A Fritsch, D.,Bengtson, G. %D 2006 %J Advanced Engineering Materials %N 5 %P 386-389 %R doi:10.1002/adem.200600019 %T Catalytic Polymer Membranes for high Temperature Hydrogenation of viscous Liquids %U https://doi.org/10.1002/adem.200600019 5 %X Polymeric membranes with high oil fluxes were developed and catalytically activated by a new route of direct calcination of polymeric membranes charged by Pd or Pt catalyst precursors. High concentrations of citric acid mixed with the precursors afforded a decrease of the calcination temperature to 175°C. Membrane reactor tests in the flow through contactor mode displayed high reactivities for sunflower oil hydrogenation. Pt showed a similar activity to Pd catalysts as measured by iodine value and generated about 13% less trans-isomers but 5% more stearic acid at an iodine value of 90. By means of alumina supported catalysts tests of methyl oleate (cis-C18:1) and methyl elaidate (trans-C18:1) hydrogenation exhibited a different pathway of reaction by either isomerization followed by reduction (Pd) or primarily direct reduction to methyl stearate (Pt). %0 journal article %@ 1022-1360 %A Mueller, A.J.,Lorenzo, A.T.,Arnal, M.L.,Boschetti de Fierro, A.,Abetz, V. %D 2006 %J Macromolecular Symposia %N 1 %P 114-122 %R doi:10.1002/masy.200650815 %T Self-Nucleation Behavior of the Polyethylene Block as Function of the Confinement Degree in Polyethylene-Block-Polystyrene Diblock Copolymers %U https://doi.org/10.1002/masy.200650815 1 %X A series of well defined polyethylene-b-polystyrene diblock copolymers (ExSyz, where x and y represent the composition in weight % and z the molecular weight in Kg/mol) has been synthesized in a wide composition range by sequential anionic polymerization. The molecular weight of the PE block was kept constant. A fractionated crystallization behavior was observed for the PE block within E26S74105 (PE cylinders) and E11S89244 (PE spheres). When the PE blocks form a continuous or percolated phase (PE, E79S2141 and E53S4751), a classic self-nucleation behavior (where the usual three self-nucleation domains are obtained) was observed. When the PE block is located within isolated microphases (having dimensions on the nanometer scale) and a fractionated crystallization was detected (E26S74105 and E11S89244), the fraction of crystals formed at higher temperatures exhibits a classic self-nucleation behavior, while those crystals that crystallized at the largest supercooling (lower exotherms) can only be self-nucleated at lower temperatures where annealing of unmolten material has already started. An unusual fractionated crystallization behavior for isolated, spherical PE microphases (E11S89244) is reported. %0 journal article %@ 0376-7388 %A Gomes, D.,Peinemann, K.-V.,Pereira Nunes, S.,Kujawski, W.,Kozakiewicz, J. %D 2006 %J Journal of Membrane Science %N 1-2 %P 747-753 %R doi:10.1016/j.memsci.2006.05.002 %T Gas Transport Properties of Segmented Poly(ether siloxane urethane urea) Membranes %U https://doi.org/10.1016/j.memsci.2006.05.002 1-2 %X Poly(ether siloxane urethane urea) with different polysiloxane contents were synthesized and characterized. The single gas permeation properties of poly(ether siloxane urethane urea) membranes were determined at 30 °C for O2, N2, CO2, CH4, n-C4H10. Their structures and gas permeation properties were compared. Significant correlation among the polysiloxane soft segment with the permeation properties was found. In addition, an analysis of the viability to use these membranes for n-C4H10/CH4 separation was made. A membrane with interesting properties such as higher n-C4H10/CH4 selectivity for a mixture of gases than for single gases was obtained, indicating a possibility of application of the poly(siloxane urethane) membranes for n-C4H10/CH4 separation. %0 journal article %@ 0024-9297 %A Kricheldorf, H.R.,Fritsch, D.,Vakhtangishvili, L.,Lomadze, N.,Schwarz, G. %D 2006 %J Macromolecules %N 15 %P 4990-4998 %R doi:10.1021/ma051398s %T Cyclic Ladder Polymers Based on 5,5’,6,6’-Tetrahydroxy-3,3,3’,3’-tetramethylspirobisindane and 2,3,5,6-Tetrafluoropyridines %U https://doi.org/10.1021/ma051398s 15 %X Silylated 5,5¢,6,6¢-tetrahydroxy-3,3,3¢,3¢-tetramethylspirobisindane, TTSBI, was polycondensed with,2,3,5,6-tetrafluoropyridine, 4-cyanotetrafluoropyridine (CTFP), or pentafluoropyridine. In the latter case, crosslinked products were obtained even under mild conditions. All other polycondensations yielded soluble ladder polymers. N-Methylpyrrolidine or sulfolane was used as reaction media, and both time and temperature were varied. In NMP, a nearly quantitative conversion was achieved even at 60 °C. With the exception of the,predominantly formed cyclic tetramer, even- and odd-numbered cycles were formed with equal probabilities.,The formation of the cyclic trimer indicates a considerable flexibility of the ladder structure. In sulfolane the,conversion was incomplete even at 100 °C, but only even-numbered cycles were formed (detectable up to 10 000 Da). Analogous polycondensations of 2,3,5,6-tetrafluoropyridine (TFP) suffered from its lower reactivity and,high volatility, resulting in a stoichiometric imbalance. TFP yielded odd- and even-numbered cycles in both solvents NMP and sulfolane, and even the strained cyclic dimer was formed, indicating a rather high flexibility of these ladder polymers. Linear oligomers having degrees of polymerization (DPs) around 10 or 15 were prepared,from CTFP by means of substituted catechols as chain stoppers. Equimolar mixtures with cyclic ladder polymers did not indicate a selective detection of cycles by MALDI-TOF mass spectrometry. %0 journal article %@ 1022-1360 %A Vivas, M.,Contreras, J.,Lopez-Carrasquero, F.,Lorenzo, A.T.,Arnal, M.L.,Balsamo, V.,Mueller, A.J.,Laredo, E.,Schmalz, H.,Abetz, V. %D 2006 %J Macromolecular Symposia %N 1 %P 58-67 %R doi:10.1002/masy.200690110 %T Synthesis and Characterization of Triblock Terpolymers with three Potentially Crystallisable Blocks: Polyethylene-b-poly(ethylene oxide)-b-poly(Epsilon-caprolactone) %U https://doi.org/10.1002/masy.200690110 1 %X A first attempt was made to produce novel ABC triblock terpolymers with three potentially crystallisable blocks: polyethylene (PE), poly(ethylene oxide) (PEO), and poly(e-caprolactone) (PCL). Polybutadiene-b-poly(ethylene oxide) diblock copolymers were synthesized by living anionic polymerization. Then, a non-catalyzed thermal polymerization of e-caprolactone from the hydroxyl end group of the PB-b- PEO diblock precursors was performed. Finally, hydrogenation by Wilkinson catalyst produced PE-b-PEO-b-PCL triblock terpolymers. Side reactions were detected that lead,to the formation of undesired PCL-b-PEO diblock copolymers, however, these impurities were successfully removed by purification. A range of triblock terpolymers with PCL and PEO minor components were prepared. Topological restrictions on the PEO middle block prevented this block from crystallizing while the complex crystallization behavior of the PE and PCL blocks was documented by DSC and WAXS,measurements. %0 journal article %@ 0032-3934 %A Abetz, V.,Peinemann, K.-V.,Simon, P.,Rojas Rivas, D.J. %D 2006 %J Polymer Preprints %N 2 %P 748 %T Design of Microphase Morphologies Using Hierarchic Self-Assembly in Blends with block Copolymers %U 2 %X Block copolymers represent a fascinating class of materials. Two or more chemically different polymer chains are linked together to give a linear or branched macromolecule. %0 journal article %@ 1550-6703 %A Abetz, V. %D 2006 %J PMSE Preprints %N %P 122-123 %T Multiphase Systems based on Block Copolymers %U %X Block copolymers represent a fascinating class of materials. Two or more chemically different polymer chains are linked together to give a linear or branched macromolecule. Due to the usually repulsive interactions between,dissimilar type of segments the different blocks (i.e. homo- or random copolymer subchains) segregate from each other leading to a microphase separated structure.1,2,3,4 In this contribution an overview on our work on amorphous and crystalline block copolymers will be given. %0 journal article %@ 0892-7022 %A Ruckdaeschel, H.,Sandler, J.K.W.,Altstaedt, V.,Rettig, C.,Schmalz, H.,Abetz, V.,Mueller, A.H.E. %D 2006 %J Polymer %N 8 %P 2772-2790 %R doi:10.1016/j.polymer.2006.02.064 %T Compatibilisation of PPE/SAN blends by triblock terpolymers - Correlation between block terpolymercomposition, morphology and properties %U https://doi.org/10.1016/j.polymer.2006.02.064 8 %X Immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-coacrylonitrile)(SAN) with a weight composition of 60/40 were compatibilised by polystyreneblock-,polybutadiene-block-poly(methyl methacrylate) triblock terpolymers (SBM) using a two-stage melt-processing approach. In order to investigate the influence of the SBM,composition on the compatibilisation efficiency, the block lengths of the triblock terpolymers were systematically varied. The resulting morphological features of the blend systems as,function of SBM composition and processing parameters are correlated with the resulting thermal and thermo-mechanical properties. In the ideal case, SBM should be located at the interface as PS is miscible with PPE while PMMA is miscible with SAN. The elastomeric middle block as an immiscible component should remain at the interface. This particular morphological arrangement is known as the “raspberry morphology”. A detailed TEM analysis of the blend morphologies following initial extrusion-compounding revealed a high compatibilisation efficiency of the SBM types with equal lengths of the end blocks and, furthermore, the desired raspberry morphology was achieved. In contrast, high PS contents in comparison to the other blocks led to a pronounced micelle formation in the PPE phase.,Further evaluation of the blend structures following injection-moulding indicated that the,morphologies remain relatively stable during this second melt-processing step. A detailed thermal analysis of all blend systems supports the interpretation of the observed,morphological features. The fundamental correlation between SBM composition and blend,morphology established in this study opens the door for the controlled development of interfacial properties of such compatibilised PPE/SAN blends during melt-processing. %0 journal article %@ 1438-1656 %A Shishatskiy, S.,Nistor, C.,Popa, M.,Pereira Nunes, S.,Peinemann, K.-V. %D 2006 %J Advanced Engineering Materials %N 5 %P 390-397 %R doi:10.1002/adem.200600024 %T Polyimide asymmetric membranes for hydrogen separation: influence of formation conditions on gas transport properties %U https://doi.org/10.1002/adem.200600024 5 %X The asymmetric flat sheet membrane was developed for separation of hydrogen from its mixtures with other gases. The composition of the casting solution and conditions of membrane preparation were optimized for the pilot scale membrane production. The resulting membrane have a high hydrogen flux (1 m3(STP)/m2h*bar) and selectivity of H2/CH4 at least 100, the value close to intrinsic selectivity of Matrimid 5218, material used for the asymmetric structure formation. The membrane is stable against mixtures of liquid hydrocarbons and can withstand heating up to 200 °C. The non-woven fabric used as a support for the asymmetric membrane gives to the membrane excellent mechanical properties and allows to use the membrane in GKSS gas separation modules. %0 journal article %@ 1438-1656 %A Abetz, V.,Brinkmann, T.,Dijkstra, M.,Ebert, K.,Fritsch, D.,Ohlrogge, K.,Paul, D.,Peinemann, K.-V.,Pereira Nunes, S.,Scharnagl, N.,Schossig, M. %D 2006 %J Advanced Engineering Materials %N 5 %P 328-358 %R doi:10.1002/adem.200600032 %T Developments in Membrane Research: from Material via Process Design to Industrial Application %U https://doi.org/10.1002/adem.200600032 5 %X The aim of this review paper is to give an overview of the research activities of GKSS in the field of polymer based membranes. After summarizing the historic development of membrane science at GKSS, it describes different classes of polymeric materials for membranes, and the characterization of membranes. The design of membrane-based separation processes followed by examples of applications will also be presented. In the last chapter we will try to give an outlook for the future activities in membrane research. %0 journal article %@ 0083-5560 %A Ebert, K.,Maltzahn, B.,Just, R.,Luetzow, K. %D 2006 %J VDI - Berichte %N %P 217-220 %T Preparation of biodegradable polymeric nanoparticles by a membrane based process %U %X %0 journal article %@ 0376-7388 %A Kneifel, K.,Nowak, S.,Albrecht, W.,Hilke, R.,Just, R.,Peinemann, K.-V. %D 2006 %J Journal of Membrane Science %N 1-2 %P 241-254 %R doi:10.1016/j.memsci.2005.09.052 %T Hollow fiber membrane contactor for air humidity control: Modules and membranes %U https://doi.org/10.1016/j.memsci.2005.09.052 1-2 %X The application of membrane contactors in air humidity control offers advantages over the conventional treatment methods, e.g. dew pointing by cooling (high energy consumption) and direct absorption (risk of air contamination by the absorbent). In gas/liquid membrane contactors the applied absorption liquid is separated from the feed air by a liquid tight but water vapor permeable membrane. Air and absorption liquid can be operated independently of each other and large and well-defined contact areas are provided. In the present work the properties of transversal flow modules were investigated with respect to the air side pressure drop and the water vapor transport. In order to realize a reliable prevention of leakage in long-term operation composite membranes with a thin but dense layer of PDMS were applied. Main subject of this work was the investigation of coated polyetherimide hollow fiber membranes with respect to the water vapor permeance. The measurements were carried out under actual contactor conditions using prototype modules and LiCl as liquid absorbent. The influence of both the support membranes and the coating layer as well were determined. It was shown that the negative effect of the coating on the permeance could be restricted to a permeance loss of about 20% by applying a very thin coating layer. With composite membranes based on highly asymmetric support membranes water vapor permeances up to 0.64 g m−2 h−1 Pa−1 could be realized. %0 journal article %@ 0887-624X %A Kricheldorf, H.R.,Lomadze, N.,Fritsch, D.,Schwarz, G. %D 2006 %J Journal of Polymer Science A %N 18 %P 5344-5352 %R doi:10.1002/pola.21627 %T Cyclic and Telechelic Ladder Polymers derived from Tetrahydroxytetramethylspirobisindane and 1,4-Dicyanotetrafluorobenzene %U https://doi.org/10.1002/pola.21627 18 %X 5,5,6,6-Tetrahydroxy-3,3,3,3-tetramethylspirobisindane was polycondensed with 1,4-dicyanotetrafluorobenzene in four different solvents at 70 °C. In dimethylformamide, N-methylpyrrolidone, and sulfolane exclusively, cyclic polymers were detectable by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry up to masses around 13,000 Da. In dimethyl sulfoxide, linear byproducts were also found. Higher temperatures caused degradation reactions catalyzed by potassium carbonate. Polycondensations performed with the addition of 4-tert-butyl catechol or 2,2-dihydroxy binaphthyl yielded linear telechelic oligomers. Equimolar mixtures of linear and cyclic ladder polymers were examined by MALDI-TOF mass spectra to determine how the end groups and the cyclic structure influenced the signal-to-noise ratio. The results suggested a preferential detection of the linear chains. %0 journal article %@ 1022-1352 %A Lorenzo, A.T.,Arnal, M.L.,Mueller, A.J.,Boschetti de Fierro, A.,Abetz, V. %D 2006 %J Macromolecular Chemistry and Physics %N 1 %P 39-49 %R doi:10.1002/macp.200500437 %T High Speed SSA Thermal Fractionation and Limitations to the Determination of Lamellar Sizes and Their Distributions %U https://doi.org/10.1002/macp.200500437 1 %X The technique of successive self-nucleation and annealing (SSA) has been applied using differential scanning calorimetry (DSC) to a model hydrogenated polybutadiene prepared by anionic polymerization and to a commercial Ziegler-Natta ethylene/1-butene copolymer. Here, it is shown that the use of high scanning rates (50 °C · min-1) in the SSA protocol can reduce the thermal fractionation time to only 78 min in length (if 6 fractions are produced with a fractionation window of 5 °C), taking into consideration the need to compensate the increment in heating rates by reducing the sample mass. This time is much shorter than those previously achieved by thermal fractionation in the literature, where fractionation times of 12 or 24 h are common. Potentially, much higher rates could be employed by further reducing the fractionation times by SSA. For the first time, a distribution of lamellar thicknesses has been obtained by transmission electron microscopy after SSA fractionation and compared to distributions calculated by the Thomson-Gibbs equation. It is shown that the results are highly dependent on the equilibrium melting temperatures employed in the calculations, and it is recommended that the values of lamellar thicknesses obtained are checked by comparing with methylene sequence lengths derived from calibration measurements available in the literature. The Thomson-Gibbs equation is useful for comparing lamellar thickness distributions obtained by SSA with different polymers only on a semi-quantitative basis. %0 journal article %@ 0014-3057 %A Lorenzo, A.T.,Arnal, M.L.,Mueller, A.J.,Boschetti de Fierro, A.,Abetz, V. %D 2006 %J European Polymer Journal %N 3 %P 516-533 %R doi:10.1016/j.eurpolymj.2005.09.001 %T Confinement effects on the crystallization and SSA thermal fractionation of the PE block within PE-b-PS diblock copolymers %U https://doi.org/10.1016/j.eurpolymj.2005.09.001 3 %X Well defined polyethylene-b-polystyrene (PE-b-PS) diblock copolymers have been synthesized by anionic polymerization in a wide composition range, keeping the length and the microstructure of the PE block constant. These copolymers provide a model system to study the confined crystallization of PE. A fractionated crystallization behavior (i.e., multiple exotherms are observed upon cooling from the melt) was observed for the PE block within block copolymers with 26% and 11% PE (i.e., Click to view the MathML source and Click to view the MathML source diblock copolymers, where the subscripts indicate the composition in wt% and the superscript the molecular weight in kg/mol). For confined PE, annealing is always observed when the material is self-nucleated. In the case of Click to view the MathML source, most of the PE spheres crystallize at very large supercoolings, a behavior previously reported in the literature and associated with homogeneous nucleation. However, in our case, the peak crystallization temperature (i.e., Tc = 46.6 °C) is much lower (16 °C) than that reported for similar size PE nano-droplets but in diblock copolymer whose second block is chemically different to PS. We therefore conclude that the nature of the interphase between the two neighboring blocks may be responsible for such low temperature nucleation, since this Tc is still quite high with respect to the vitrification temperature of PE (in comparison with other polymers whose homogeneous nucleation temperature has been found close to Tg), a fact that could indicate that the homogeneous nucleation temperature has not been reached because surface (or interfacial) effects can dominate. Thermal fractionation takes advantage of the distribution of methyl sequence length in hydrogenated polybutadiene in order to produce by successive thermal annealing a distribution of lamellar thickness within each PE block. Such a distribution of thermal fractions is affected by confinement and therefore these experiments demonstrate the influence of morphological restrictions on the crystallization of the PE block within the PE-b-PS diblock copolymers. As the PE content in the copolymer decreases, topological confinement effects limit the size of the lamellar crystals that can be formed within the reduced dimensions of the microdomains (MD). By the use of the Gibbs-Thomson equation and the thermal fractionation results, a distribution of crystalline lamellar thickness within each MD was obtained and the orientation of the chains within the MD was deduced. %0 journal article %@ 0892-7022 %A Boeker, A.,Schmidt, K.,Knoll, A.,Zettl, H.,Haensel, H.,Urban, V.,Abetz, V.,Krausch, G. %D 2006 %J Polymer %N 3 %P 849-857 %R doi:10.1016/j.polymer.2005.11.069 %T The influence of incompatibility and dielectric contrast on the electric field-induced orientation of lamellar block copolymers %U https://doi.org/10.1016/j.polymer.2005.11.069 3 %X We investigate the influence of incompatibility and dielectric contrast on the reorientation kinetics of concentrated solutions of lamellar block copolymers in the presence of an external DC electric field. We study solutions of AC diblock copolymer and ABC triblock terpolymers. The inclusion of a short, polar middle block B is used to tailor both the degree of incompatibility and the dielectric contrast between the two majority,phases. In situ synchrotron radiation small-angle X-ray scattering is used to monitor the reorientation process. For the AC diblock copolymer,sample only weak electric field induced reorientation could be achieved, following a very slow kinetics, whereas for the ABC triblock terpolymer, reorientation is observed above a threshold value of 0.3 kV/mm. The orientation kinetics is well described by a single exponential with characteristic time constants varying between a few seconds and several minutes depending on the polymer concentration and the electric field,strength. We identify a narrow concentration window, in which the interplay between chain mobility and gain in free energy in the electric field allows the preparation of highly anisotropic bulk polymer samples by exposure to an electric field. The results are compared to free energy,calculations revealing a distinct difference in the driving force for reorientation as a consequence of an increase in dielectric contrast and chain mobility upon introduction of the B middle block. %0 journal article %@ 0376-7388 %A Roeder, J.,Zucolotto, V.,Shishatskiy, S.,Bertolino, J.,Pereira Nunes, S.,Pires, A. %D 2006 %J Journal of Membrane Science %N 1-2 %P 70-75 %R doi:10.1016/j.memsci.2005.11.037 %T Mixed conductive membrane: Aniline polymerization in an acid SPEEK matrix %U https://doi.org/10.1016/j.memsci.2005.11.037 1-2 %X Mixed ion/electron conductive ceramic materials, like perovskite, have recently gained relevance due to their possible applications in membrane technology. This work describes the preparation and characterization of a mixed conductive membrane obtained via in situ polymerization of polyaniline (PANI) within a sulfonated poly(ether ether ketone) (SPEEK) matrix. Mixed conductive membranes of PANI/SPEEK obtained from an initial composition of 80 wt.% SPEEK had an electronic conductivity of 1×10−5 S cm−1 and after a second doping with 1 mol L−1 HCl it increased to 4.9×10−5 S cm−1. The doping of PANI with SPEEK was evaluated by infrared spectroscopy, with intense broad bands at 1137 and 1157 cm−1. These bands were characteristic of the protonated imine structure of PANI, and also the reduction of quinoid units due to the interaction,of the sulfonic groups of SPEEK with nitrogen atoms of PANI. The PANI doping efficiency with SPEEK, the conducting path formation at the,percolation threshold and a good thermal stability of the system make it possible to obtain mixed conductive membranes. %0 journal article %@ 0011-9164 %A Antonucci, V.,Arico, A.,Baglio, V.,Brunea, J.,Buder, I.,Cabello, N.,Hogarth, M.,Martin, R.,Pereira Nunes, S. %D 2006 %J Desalination %N 1-3 %P 653-655 %R doi:10.1016/j.desal.2006.03.489 %T Membranes for portable direct alcohol fuel cells %U https://doi.org/10.1016/j.desal.2006.03.489 1-3 %X No abstract %0 journal article %@ 0920-5861 %A Fritsch, D.,Bengtson, G. %D 2006 %J Catalysis Today %N 1-2 %P 121-127 %R doi:10.1016/j.cattod.2006.01.039 %T Development of catalytically reactive porous membranes for the selective hydrogenation of sunflower oil %U https://doi.org/10.1016/j.cattod.2006.01.039 1-2 %X The main objective of this contribution was to develop and validate new catalytically reactive porous membranes for hydrogenation of edible oil in a membrane reactor. High flux polymer membranes from polyethersulfone and polyamideimide with and without inorganic alumina filler were produced on a technical membrane casting machine. These porous membranes show water fluxes of about 30,000 L/m2 h bar and oil fluxes of 900–2000 L/m2 h bar at 60 °C. The pore volumes are in the range of 5–7 mL/100 cm2 of membrane area. Large pores at high porosity were received by addition of a water soluble ethyleneoxide-propyleneoxide-b-copolymer (Pluronic® F127), that forms distinctive globules in the solution when cooled below 10 °C. The catalytic activity was obtained by two different methods: by wet impregnation of the membrane in a catalyst precursor solution (palladium acetate or hexachloroplatinate) followed by calcination, respectively, chemical reduction or by addition of ready-made supported catalysts to the membrane casting solutions. Catalytically activated membranes with different Pt-contents (0.1–1 g/m2) were applied in first membrane reactor tests to hydrogenate refined sunflower oil. Within 6 h the iodine value decreased considerably and about a half of the linoleic acid was hydrogenated, which is the major compound in sunflower oil triglycerides. The overall trans-content of the fatty acids was about 25%. Membrane performance was verified in up to 5 days of discontinuous operation. %0 journal article %@ 0011-9164 %A Gomes, D.,Buder, I.,Pereira Nunes, S. %D 2006 %J Desalination %N 1-3 %P 274-276 %R doi:10.1016/j.desal.2006.03.066 %T Novel Proton Conductive Membranes containing Sulfonated Silica %U https://doi.org/10.1016/j.desal.2006.03.066 1-3 %X No abstract %0 journal article %@ 0376-7388 %A Ebert, K.,Koll, J.,Dijkstra, M.,Eggers, M. %D 2006 %J Journal of Membrane Science %N 1-2 %P 75-80 %R doi:10.1016/j.memsci.2006.07.037 %T Fundamental studies on the performance of a hydrophobic solvent stable membrane in non-aqueous solutions %U https://doi.org/10.1016/j.memsci.2006.07.037 1-2 %X Hydrophobic solvent resistant membranes were tested for the rejection of low molecular weight polymers in organic solvents with systematically varying compositions. Poly(ethylene glycols) (PEGs) of 400, 900 and 1500 Da were dissolved in solvent mixtures containing ethanol and different amounts of n-pentane, n-hexane, n-dodecane or toluene. Solvent permeabilities increased with increasing amount of alkane or toluene in mixtures with ethanol. For PEG 900 and 1500 retentions slightly decreased with increasing amount of alkane or toluene in these mixtures. For PEG 400, however, retentions increased when concentration of alkanes and toluene increased in the mixtures. The retention results were discussed in terms of the transport mechanism and the interactions between membrane material, solvents and solute. %0 journal article %@ 1022-1352 %A Karthikeyan, C.,Pereira Nunes, S.,Schulte, K. %D 2006 %J Macromolecular Chemistry and Physics %N 3 %P 336-341 %R doi:10.1002/macp.200500463 %T Permeability and conductivity studies on ionomer-polysilsesquioxane hybrid materials %U https://doi.org/10.1002/macp.200500463 3 %X Hybrid materials based on sulphonated poly(ether ether ketone) (SPEEK, ionomer) and (RSiO1.5)n network (polysilsequioxane) were prepared by sol-gel process. Two different precursors namely aminopropyl trimethoxysilane (APTMS) and imidazoleglycidoxypropyl trimethoxysilane (IGPTMS) were utilized to generate (RSiO1.5)n in SPEEK matrix by sol-gel process. 29Si MAS NMR confirmed the formation of RSiO3/2 network structure inside the matrix. Characterisation of the hybrid materials showed lower methanol and water permeability compared to the plain SPEEK. They are therefore promising materials as membranes for direct methanol fuel cells applications. The hybrid material derived from amino group was more effective in decreasing the permeability than the material derived from imidazole group. However, the proton conductivity of the latter was higher than the material derived from amino group. The results indicate that hybrid material prepared from imidazole containing silane is more suitable as a membrane for direct methanol fuel cell than the one prepared from amino carrying silane because it fulfils the two main requirements, namely low methanol permeability and reasonably good proton conductivity. %0 journal article %@ 1022-1360 %A Mueller, A.J.,Lorenzo, A.T.,Castillo, R.V.,Arnal, M.L.,Boschetti de Fierro, A.,Abetz, V. %D 2006 %J Macromolecular Symposia %N 1 %P 154-160 %R doi:10.1002/masy.200651321 %T Crystallization Kinetics of Homogeneous and Melt Segregated PE Containing Diblock Copolymers %U https://doi.org/10.1002/masy.200651321 1 %X The crystallization behavior of four types of polyethylene (PE) containing diblock copolymers with an approximate 50/50 composition has been investigated and compared with their respective PE homopolymers. A glassy block of polystyrene (PS), a rubbery block of poly (D,L-lactide) (PDLA), a semicrystalline block of poly,(L-lactide) (PLLA) and a miscible block of (poly(ethylene-alt-propylene) (PEP) were used to asses the influence of the degree of confinement and miscibility on the crystallization kinetics of PE. PEP had the largest effect on the crystallization kinetics of the,PE block in view of its miscibility. For the strongly segregated systems larger restrictions were imposed by vitreous PS due to hard confinement as compared with the soft confinement of the rubbery PDLA block. A nucleation effect of,previously crystallized PLLA on the PE block was detected which offset its depression of the crystallization kinetics of PE. %0 journal article %@ 0011-9164 %A Khotimskiy, V.,Chirkova, M.,Litvinova, E.,Konrad, M.,Lecerf, N.,Yave, W.,Shishatskiy, S.,Peinemann, K.-V. %D 2006 %J Desalination %N 1-3 %P 198-199 %R doi:10.1016/j.desal.2006.03.046 %T Poly(1-trimethylgermyl-1-propyne): synthesis, characterisation and transport properties of pure polymers and nanocomposites %U https://doi.org/10.1016/j.desal.2006.03.046 1-3 %X No abstract %0 journal article %@ 0011-9164 %A Shishatskiy, S.,Nistor, C.,Popa, M.,Pereira Nunes, S.,Peinemann, K.-V. %D 2006 %J Desalination %N 1-3 %P 193-194 %R doi:10.1016/j.desal.2006.03.044 %T Comparison of asymmetric and thin-film composite membranes having Matrimid 5218 selective layer %U https://doi.org/10.1016/j.desal.2006.03.044 1-3 %X No abstract %0 journal article %@ 0011-9164 %A Peinemann, K.-V.,Konrad, M.,Abetz, V. %D 2006 %J Desalination %N 1-3 %P 124-126 %R doi:10.1016/j.desal.2006.03.155 %T Highly ordered membrane structures from block copolymers %U https://doi.org/10.1016/j.desal.2006.03.155 1-3 %X No abstract %0 journal article %@ 1438-1656 %A Karthikeyan, C.,Pereira Nunes, S.,Schulte, K. %D 2006 %J Advanced Engineering Materials %N 10 %P 1010-1015 %R doi:10.1002/adem.200600147 %T Barrier properties of poly(benzimidazole)-layered silicates nanocomposite materials %U https://doi.org/10.1002/adem.200600147 10 %X No abstract %0 journal article %@ 0887-6266 %A Gomes, D.,Buder, I.,Pereira Nunes, S. %D 2006 %J Journal of Polymer Science B %N 16 %P 2278-2298 %R doi:10.1002/polb.20868 %T Sulfonated Silica-based Electrolyte Composite Membranes %U https://doi.org/10.1002/polb.20868 16 %X New functionalized particles were prepared by attaching sulfonated aromatic bishydroxy compounds onto fumed silica surface. First, a bromophenyl group was introduced onto the silica surface by reaction of bromophenyltrimethoxysilane,with fumed silica. Then, sulfonated bishydroxy aromatic compounds were chemically attached to the silica surface by nucleophilic substitution reactions. The structure of the modified silica was characterized by elemental analysis: 13C-NMR, 29Si-NMR, and FTIR. Afterward, novel inorganic–organic electrolyte composite membranes based on sulfonated poly(ether ether ketone) have been developed using the sulfonated aromatic bishydroxy compounds chemically attached onto the fumed silica surface. The composite membrane prepared using silica with sulfonated hydroxytelechelic, containing 1,3,4-oxadiazole units, has higher proton conductivity values in all range of temperatures (40–140°C) than the membrane containing only the plain electrolyte polymer, while the methanol permeability determined by pervaporation experiment was unchanged. A proton conductivity up to 59 mS cm1 at 140°C was,obtained. The combination of these effects may lead to significant improvement in fuel cells (fed with hydrogen or methanol) at temperatures above 100°C. %0 journal article %@ 0376-7388 %A Silva, V.,Mendes, A.,Madeira, L.,Pereira Nunes, S. %D 2006 %J Journal of Membrane Science %N 1-2 %P 126-134 %R doi:10.1016/j.memsci.2005.09.037 %T Proton exchange membranes for direct methanol fuel cells: Properties critical study concerning methanol crossover and proton conductivity %U https://doi.org/10.1016/j.memsci.2005.09.037 1-2 %X Generally, standard R&D procedures regarding the proton exchange membrane (PEM) development for direct methanol fuel cell (DMFC),applications do not allow direct conclusions concerning the PEM limiting characteristics. In this regard, a recent developed DMFC model is used to predict the influence of the PEM proton conductivity and permeability towards methanol on the DMFC performance. In addition, the application of the present model was performed in order to answer some open questions regarding the PEM properties for DMFC applications. The mathematical,model uses as inputs membrane properties obtained from easy-to-implement standard characterization methods. From the simulation results it was verified that the PEM electrolyte and barrier properties play a decisive role on the DMFC performance. The proton conductivity seems to influence mainly the DMFC current and power density and the cell efficiency regarding fuel conversion (Faraday efficiency). On the other hand, the,permeability towards methanol was found to influence all the studied DMFC outputs as it is directly related to the fuel loss and parasitic reaction of methanol in the cathode catalyst layer. As expected, the simulations show that the optimal PEM properties for DMFC applications are high proton conductivity to reduce the Ohmic losses and low permeability towards methanol in order to prevent the crossing over of methanol from the anode to the cathode. %0 journal article %@ 0011-9164 %A Silva, V.,Mendes, A.,Madeira, L.,Pereira Nunes, S. %D 2006 %J Desalination %N 1-3 %P 645-647 %R doi:10.1016/j.desal.2006.03.448 %T Pre-treatment effect on the transport properties of sPEEK membranes for DMFC application %U https://doi.org/10.1016/j.desal.2006.03.448 1-3 %X No abstract %0 journal article %@ 0376-7388 %A Silva, V.,Ruffmann, B.,Silva, H.,Mendes, A.,Madeira, L.,Pereira Nunes, S. %D 2006 %J Journal of Membrane Science %N 1-2 %P 137-144 %R doi:10.1016/j.memsci.2006.07.027 %T Zirconium oxide hybrid membranes for direct methanol fuel cells- Evaluation of transport properties %U https://doi.org/10.1016/j.memsci.2006.07.027 1-2 %X The transport properties of hybrid membranes with sulfonated poly(ether ether ketone) (sPEEK) as polymeric matrix (sulfonation degree, SD, of 71 and 87%) are studied as a function of the membrane thickness and the content of zirconium oxide (2.5, 5.0 and 7.5 wt.%), incorporated via in,situ zirconia formation. Nafion® 112, 1135 and 117 are used as reference materials. The investigated properties of the composite membranes are the proton conductivity, water uptake, methanol and water permeation fluxes and water/methanol selectivity. Impedance measurements indicate,that proton conductivity decreases when thickness increases for the sPEEK composite membrane with SD of 87%; the same effect is observed for Nafion®. In contrast, it was found that the membrane thickness has almost no effect on the proton conductivity for sPEEK with SD = 71%. In terms of water uptake, it was found that it slightly increases with the thickness for all the sPEEK membranes tested, while the effect on Nafion® is far more evident. For most of the studied membranes, methanol and water permeation fluxes, as well as selectivity towards water/methanol, decrease with the membrane thickness. Finally, it was found that the zirconium oxide incorporation in the sPEEK polymer leads to membranes with decreased proton conductivity, water swelling and water and methanol permeation fluxes. However, it increases the composite membranes selectivity towards water/methanol. %0 journal article %@ 0011-9164 %A Vetter, S.,Abetz, V.,Goerigk, G.,Buder, I.,Pereira Nunes, S. %D 2006 %J Desalination %N 1-3 %P 289-290 %R doi:10.1016/j.desal.2006.03.071 %T Polyetherketones for fuel cell application %U https://doi.org/10.1016/j.desal.2006.03.071 1-3 %X No abstract %0 journal article %@ 0011-9164 %A Brinkmann, T.,Puhst, J.,Pingel, H. %D 2006 %J Desalination %N 1-3 %P 262-264 %R doi:10.1016/j.desal.2006.03.318 %T Hybrid Processes using improved Vapour Permeation Membranes %U https://doi.org/10.1016/j.desal.2006.03.318 1-3 %X No abstract %0 journal article %@ 0376-7388 %A Dijkstra, M.,Bach, S.,Ebert, K. %D 2006 %J Journal of Membrane Science %N 1-2 %P 60-68 %R doi:10.1016/j.memsci.2006.09.012 %T A transport model for organophilic nanfiltration %U https://doi.org/10.1016/j.memsci.2006.09.012 1-2 %X The permeation of various mixtures of pentane–decane and pentane–dodecane through dense PDMS/PAN membranes has been measured in a,cross-flow membrane cell for pressures varying from 10 to 40 bar. The results have successfully been modeled with both the solution diffusion with imperfections model and the Maxwell–Stefan transport equation taking into account both diffusive and viscous flow. The modeling with the Maxwell–Stefan transport equation gave more realistic values of the estimated parameters. Increasing the pentane concentration in the feed solution reduces the percentage diffusive flow due to the increasing swelling of the membrane. %0 journal article %@ 0013-4686 %A Silva, V.S.,Ruffmann, B.,Vetter, S.,Boaventura, M.,Mendes, A.M.,Madeira, L.M.,Pereira Nunes, S. %D 2006 %J Electrochimica Acta %N 18 %P 3699-3706 %R doi:10.1016/j.electacta.2005.10.029 %T Mass transport of direct methanol fuel cell species in sulfonated poly(ether ether ketone) membranes %U https://doi.org/10.1016/j.electacta.2005.10.029 18 %X Homogeneous membranes based on sulfonated poly(ether ether ketone) (sPEEK) with different sulfonation degrees (SD) were prepared and characterized. In order to perform a critical analysis of the SD effect on the polymer barrier and mass transport properties towards direct methanol fuel cell species, proton conductivity, water/methanol pervaporation and nitrogen/oxygen/carbon dioxide pressure rise method experiments are proposed. This procedure allows the evaluation of the individual permeability coefficients in hydrated sPEEK membranes with different sulfonation degrees. Nafion® 112 was used as reference material. DMFC tests were also performed at 50 °C. It was observed that the proton conductivity and the permeability towards water, methanol, oxygen and carbon dioxide increase with the sPEEK sulfonation degree. In contrast, the SD seems to not affect the nitrogen permeability coefficient. In terms of selectivity, it was observed that the carbon dioxide/oxygen selectivity increases with the sPEEK SD. In contrast, the nitrogen/oxygen selectivity decreases. In terms of barrier properties for preventing the DMFC reactants loss, the polymer electrolyte membrane based on the sulfonated poly(ether ether ketone) with SD lower or equal to 71%, although having slightly lower proton conductivity, presented much better characteristics for fuel cell applications compared with the well known Nafion® 112. In terms of the DMFC tests of the studied membranes at low temperature, the sPEEK membrane with SD = 71% showed to have similar performance, or even better, as that of Nafion® 112. However, the highest DMFC overall efficiency was achieved using sPEEK membrane with SD = 52%. %0 journal article %@ 0376-7388 %A Parcero, E.,Herrera, R.,Pereira Nunes, S. %D 2006 %J Journal of Membrane Science %N 1-2 %P 206-213 %R doi:10.1016/j.memsci.2005.12.065 %T Phosphonated and sulfonated polyphenylsulfone membranes %U https://doi.org/10.1016/j.memsci.2005.12.065 1-2 %X Membranes of phosphonated polyphenylsulfone with functionalization degree up to 88–106% were prepared by reaction in the presence of Pd(0)-complexes. Membranes of phosphonated and sulfonated polyphenylsulfone were also prepared by sulfonating previously phosphonated polyphenylsulfone. The membrane proton conductivities were evaluated by impedance spectroscopy at the temperature range between 50 and 150 °C. While sulfonated membranes had higher proton conductivity at 100% relative humidity, they swell much more than the phosphonated films in water and have a much higher permeability to water and methanol. Phosphonated films are thermally more stable. %0 journal article %@ 0032-3934 %A Albuerne, J.,Boschetti de Fierro, A.,Simon, P.F.W.,Abetz, V. %D 2006 %J Polymer Preprints %N 2 %P 557-558 %T Modification of polymeric surfaces for the improvement of thermoplastic composites %U 2 %X No abstract %0 journal article %@ 0011-9164 %A Bengtson, G.,Fritsch, D. %D 2006 %J Desalination %N 1-3 %P 666-667 %R doi:10.1016/j.desal.2006.03.476 %T Catalytic membrane reactor for the selective hydrogenation of edible oil: Platinum versus Palladium catalyst %U https://doi.org/10.1016/j.desal.2006.03.476 1-3 %X No abstract %0 journal article %@ 0142-9612 %A Unger, R.E.,Peters, K.,Huang, Q.,Funk, A.,Paul, D.,Kirkpatrick, C.J. %D 2005 %J Biomaterials %N 17 %P 3461-3469 %R doi:10.1016/j.biomaterials.2004.09.047 %T Vascularization and gene regulation of human endothelial cells growing on porous polyethersulfone (PES) hollow fiber membranes %U https://doi.org/10.1016/j.biomaterials.2004.09.047 17 %X Open-cell hollow fibers made of polyethersulfone (PES) manufactured in the absence of solvents with pore diameters smaller than 100 μm were examined for vascularization by human endothelial cells. The goal of this study was to determine whether the 3-D porous character of the PES surface affected human endothelial cell morphology and functions. Freshly isolated human endothelial cells from the skin (HDMEC), from the lung (HPMEC) and from umbilical cords (HUVEC) and two human endothelial cell lines, HPMEC-ST1.6R and ISO-HAS.c1 were added to PES fibers and cell adherence and growth was followed by confocal laser scanning microscopy. Prior coating of PES with gelatin or fibronectin was necessary for adhesion and spreading of cells over the uneven porous surface with time. Confluent cells exhibited typical strong PECAM-1 expression at cell–cell borders. Little expression of the activation markers E-selectin, ICAM-1, and VCAM-1 was observed by RT-PCR of endothelial cells growing on PES. However, after stimulation for 4 h by LPS, activation of these markers was observed and it was shown by immunofluorescent staining that induction occurred in most of the cells, thus confirming an intact functionality. Finally, cells growing as a monolayer on PES migrated to form microvessel-like structures when placed under conditions that stimulated angiogenesis. Thus, human endothelial cells grown on fibronectin-coated PES fibers retain important endothelial-cell specific morphological and functional properties and PES may serve as a useful biomaterial in tissue engineering and biotechnology applications. %0 journal article %@ 0947-6539 %A McKeown, N.B.,Budd, P.M.,Msayib, K.J.,Ghanem, B.S.,Kingston, H.J.,Tattershall, C.E.,Makhseed, S.,Reynolds, K.J.,Fritsch, D. %D 2005 %J Chemistry - A European Journal %N 9 %P 2610-2620 %R doi:10.1002/chem.200400860 %T Polymers of Intrinsic Microporosity (PIMs): Bridging the Void between Microporous and Polymeric Materials %U https://doi.org/10.1002/chem.200400860 9 %X Novel types of microporous material are required for chemoselective adsorptions, separations and heterogeneous catalysis. This concept article describes recent research directed towards the synthesis of polymeric materials that possess microporosity that is intrinsic to their molecular structures. These polymers (PIMs) can exhibit analogous behaviour to that of conventional microporous materials, but, in addition, may be processed into convenient forms for use as membranes. The excellent performance of these membranes for gas separation and pervaporation illustrates the unique character of PIMs and suggests immediate technological applications. %0 journal article %@ 1292-8941 %A Fustin, C.-A.,Abetz, V.,Gohy, J.-F. %D 2005 %J The European Physical Journal E %N 3 %P 291-302 %R doi:10.1140/epje/i2004-10086-0 %T Triblock terpolymer micelles: A personal outlook %U https://doi.org/10.1140/epje/i2004-10086-0 3 %X This outlook paper focuses on micelles formed by ABC triblock copolymers (triblock terpolymers) and related systems resulting from mixtures of diblock copolymers. Micelles with different internal structure such as micelles with a heterogeneous core and a homogeneous corona or micelles with a homogeneous core and a mixed corona are presented. More complex nanoobjects such as vesicles and Janus particles are also reviewed. Finally, potential applications of these objects are discussed. %0 journal article %@ 0024-9297 %A Peng, C.-C.,Abetz, V. %D 2005 %J Macromolecules %N 13 %P 5575-5580 %R doi:10.1021/ma050419f %T A Simple Pathway toward Quantitative Modification of Polybutadiene: A New Approach to Thermoreversible Crosslinking Rubber Comprising Supramolecular Hydrogen Bonding Networks %U https://doi.org/10.1021/ma050419f 13 %X A commercial polybutadiene (PB) was modified by a simple three-step polymer analogous reaction (epoxidation, oxirane ring-opening, and sulfonyl isocyanate addition), and the degree of modification is quantitatively controlled by epoxidation reaction. Because of the introduction of sulfonyl urethane groups (-O-CO-NH-SO2-) which is prone to self-complementary thermoreversible supramolecular hydrogen-bonding (HB) networks, the PB was modified from a rubbery material to a thermoplastic elastomer. The modified rubbers were characterized by using 1H NMR, FTIR, DSC, and dynamic mechanical analyses. FTIR spectra showed a shift of S=O stretching to lower frequency with increasing degree of modification as a result of the formation of HB complexes. DSC analysis showed that the crystalline melting was suppressed, and the glass transition was elevated to higher temperatures. From the dynamic mechanical analysis it revealed much clearer the crystallization suppression and the glass transition shifts. The changes in thermal and mechanical properties were attributed to the formation of HB supramolecular networks in the modified polybutadienes. %0 journal article %@ 0142-9612 %A Unger, R.E.,Huang, Q.,Peters, K.,Protzer, D.,Paul, D.,Kirkpatrick, C.J. %D 2005 %J Biomaterials %N 14 %P 1877-1884 %R doi:10.1016/j.biomaterials.2004.05.032 %T Growth of human cells on polyethersulfone (PES) hollow fiber membranes %U https://doi.org/10.1016/j.biomaterials.2004.05.032 14 %X A novel material of porous hollow fibers made of polyethersulfone (PES) was examined for its ability to support the growth of human cells. This material was made in the absence of solvents and had pore diameters smaller than 100 μm. Human cell lines of different tissue and cell types (endothelial, epithelial, fibroblast, glial, keratinocyte, osteoblast) were investigated for adherence, growth, spread and survival on PES by confocal laser microscopy after staining of the cells with Calcein-AM. Endothelial cell attachment and growth required pre-coating PES with either fibronectin or gelatin. The other cell types exhibited little difference in growth, spread or survival on coated or uncoated PES. All the cells readily adhered and spread on the outer, inner and cut surfaces of PES. With time confluent monolayers of cells covered the available surface area of PES and in some cases cells grew as multilayers. Many of the cells were able to survive on the PES for up to 7 weeks and in some cases growth was so extensive that the underlying PES was no longer visible. Scanning electron microscope observations of cells on the materials correlated with the confocal morphometric data. Thus, PES is a substrate for the growth of many different types of human cells and may be a useful scaffolding material for tissue engineering. %0 journal article %@ 0888-5885 %A Robinson, J.,Tarleton, S.,Ebert, K.,Millington, C.,Nijmeijer, A. %D 2005 %J Industrial & Engineering Chemistry Research %N 9 %P 3238-3248 %R doi:10.1021/ie0496277 %T Influence of Cross-Linking and Process Parameters on the Separation Performance of Poly(dimethylsiloxane) Nanofiltration Membranes %U https://doi.org/10.1021/ie0496277 9 %X The flux of an organic solvent and the rejection of organic solute molecules was studied using dense poly(dimethylsiloxane) (PDMS) membranes with different degrees of crosslinking. It was found that the transport mechanisms favoured the pore-flow concept rather than a solution-diffusion approach, and that the effective pore size of the membrane was dependent on the degree of crosslinking (and swelling propensity of the feed stream). PDMS membranes with a high degree of crosslinking gave lower solvent fluxes and increased solute rejections, implying a smaller pore size than equivalent membranes with a lower degree of crosslinking. Based on the rejection of a low-polarity poly-nuclear aromatic solute in a xylene solvent, the effective membrane pore diameter is shown to vary between 1.7 and 2.4 nm depending on the degree of crosslinking.,A comparison of thirteen different PDMS samples with varying thickness and crosslinking showed a correlation between solvent induced membrane permeability, solute rejection and effective membrane pore size. The results suggests that if the thickness of the PDMS layer is known, the effective pore size and separation performance of crosslinked PDMS membranes can be determined by a simple measurement of solvent flux. %0 journal article %@ 0376-7388 %A Gomes, D.,Pereira Nunes, S.,Peinemann, K.-V. %D 2005 %J Journal of Membrane Science %N 1 %P 13-25 %R doi:10.1016/j.memsci.2004.05.015 %T Membranes for gas separation based on poly(1-trimethyl-1-propyne)-silica nanocomposites %U https://doi.org/10.1016/j.memsci.2004.05.015 1 %X Nanocomposite membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) and silica were synthesized by sol–gel copolymerizationof tetraethoxysilane (TEOS) with different organoalkoxysilanes in tetrahydrofuran solutions of PTMSP. The influence of the synthesis parameters (type and concentration of organoalkoxysilanes, temperature and time) on the silica conversion and the gas permeation performanceof PTMSP–silica nanocomposite membranes was investigated and discussed in this paper. The nanocomposite membranes were characterizedby single and mixed gas permeation, thermogravimetric analysis and scanning electron microscopy. The butane permeability and the butane/methane selectivity increased simultaneously when high silica conversion was obtained and the size of particle was in the range20–40 nm. For the sake of comparison, nanocomposite membranes based on PTMSP were also prepared by dispersing silica particles withdifferent functional groups into the PTMSP casting solution. The addition of fillers to the polymer matrix can be performed up to a highercontent of silica (30% silica-filled PTMSP in contrast to 6 wt.% for the in situ-generated silica). In this case, the simultaneous increase in,butane permeability and butane/methane selectivity was significantly higher when compared to the nanocomposite membranes prepared by sol–gel process. The addition of fillers with 50% of surface modification with hydrophobic groups (Si–C8H17 and Si–C16H33) seems not to lead to a significant increase of the butane/methane selectivity and butane permeability when compared to the silica with hydrophilic surface groups, probably because of the unfavorable polymer/filler interaction, leading to an agglomeration of the long n-alkyl groups at the surfaceof the polymer. An increase of butane permeability up to six-fold of unfilled polymer was obtained. %0 journal article %@ 1042-7147 %A Peng, C.-C.,Goepfert, A.,Drechsler, M.,Abetz, V. %D 2005 %J Polymers for Advanced Technologies %N %P 770-782 %R doi:10.1002/pat.666 %T ‘‘Smart’’ silica-rubber nanocomposites in virtue of hydrogen bonding interaction %U https://doi.org/10.1002/pat.666 %X In this paper ‘‘smart’’ nanocomposites comprising Stoeber silica nanoparticles of two different,surface polarities and a novel thermoreversible crosslinking rubber carrying self-complementary,hydrogen bonding (HB) moiety were presented. This strategy is based on the idea that the introduction of HB between silica and the modified rubber improves both the filler–rubber interaction and the mechanical properties. The resulting nanocomposites were mainly characterized using transmission electron microscopy (TEM) and dynamic mechanical analysis. It is found that the competition and symbiosis between the filler–filler, filler–rubber and rubber–rubber,HB interaction, as well as the dynamic mechanical properties were controllable simply by changing,the silica loading, the degree of rubber modification and the temperature. Besides, the TEM,micrographs showed that the modifications of both silica nanoparticles and rubber promoted better silica dispersion in the rubber matrix. By this strategy it is evident that the Payne effect was reduced and it is possible to modify the mechanical properties of such silica filled composites in a controlled way, which could, as an example, meet the requirements for tire applications. %0 journal article %@ 1022-1352 %A Kricheldorf, H.R.,Fritsch, D.,Vakhtangishvili, L.,Schwarz, G. %D 2005 %J Macromolecular Chemistry and Physics %N 22 %P 2239-2247 %R doi:10.1002/macp.200500280 %T Cyclic Ladder Polymers by Polycondensation of Silylated Tetrahydroxy-tetramethylspirobisindane with 1,4-Dicyanotetrafluorobenzene %U https://doi.org/10.1002/macp.200500280 22 %X 5,5’,6,6’-Tetra(trimethylsiloxy)4,4,4,4’-tetramethyl-1,1-spirobisindane (TTSBI),was polycondensed with 1,4-dicyanotetrafluorobenzene (DCTB) under variation of solvent,temperature, time and feed ratio. Under optimized reaction conditions, all products detectable by MALDI-TOF mass spectrometry (up to masses around 8 000 Da) proved to be cyclic ladder oligomers and polymers. In N-methylpyrrolidone and dimethylsulfoxide oddnumbered,cycles were formed in addition to the prevailing even-numbered ones. However, in sulfolane exclusively even-numbered cycles were obtained (detectable up to masses around,10 000 Da), together with even-numbered linear chains. Temperatures above 100°C enhanced,the molecular weights by side reactions. With the less reactive cyano-2,3,5,6-,tetrafluorobenzene (CTB) again cycles were formed, but their content and the conversions,were lower. Polycondensation of CTB up to 160°C and all polycondensations of,cyanopentafluorobenzene gave crosslinked products. %0 journal article %@ 0887-624X %A Kricheldorf, H.R.,Fan, S.-C.,Vakhtangishvili, L.,Schwarz, G.,Fritsch, D. %D 2005 %J Journal of Polymer Science A %N 24 %P 6272-6281 %R doi:10.1002/pola.21087 %T Polyimides Based on New Diamines Having Pendant Imide Groups %U https://doi.org/10.1002/pola.21087 24 %X New aromatic diamines were prepared in two steps from 4,5-dichlorophthalic anhydride and primary amines. The resulting 4,5-dichlorophthalimide was reacted with 4-mercaptoaniline, so that the chloroatoms were substituted by the mercapto groups (via the sulfide anions). The new diamines were polycondensed either with the diphenyl ether 3,3,4,4-tetracarboxylic anhydride or with bicyclooctane tetracarboxylic anhydride. These polycondensations were conducted in boiling m-cresol with azeotropic removal of water. The isolated polyimides were characterized by viscosity measurement, IR-spectroscopy, elemental analyses, and MALDI-TOF mass spectrometry. The mass spectra evidenced a high content of cyclic polyimides, indicating nearly perfect reaction conditions. The mass spectra also proved the formation of copolymers containing one diamine with a trialkylamine group in the side chain. High glass transition temperatures but a low crystallization tendency were found by DSC measurements. %0 journal article %@ 0743-7463 %A Schmidt, K.,Boeker, A.,Zettl, H.,Schubert, F.,Haensel, H.,Fischer, F.,Weiss, T.,Abetz, V.,Zvelindovsky, A.,Sevink, G.J.A.,Krausch, G. %D 2005 %J Langmuir %N 25 %P 11974-11980 %R doi:10.1021/la051346w %T Influence of Initial Order on the Microscopic Mechanism of Electric Field Induced Alignment of Block CopolymerMicrodomains %U https://doi.org/10.1021/la051346w 25 %X We investigate the mechanism of microdomain orientation in concentrated block copolymer solutions exposed to a dc electric field by in situ synchrotron small-angle X-ray scattering (SAXS). As a model system, we use concentrated solutions of a lamellar polystyrene-b-polyisoprene block copolymer in toluene.Wefind that both the microscopic mechanism of reorientation and the kinetics of the process strongly depend on the initial degree of order in the system. In a highly ordered lamellar system with the lamellae being aligned perpendicular to the electric field vector, only nucleation and growth of domains is possible as a pathway to reorientation and the process proceeds rather slowly. In less ordered samples, grain rotation,becomes possible as an alternative pathway, and the process proceeds considerably faster. The interpretation of our finding is strongly corroborated by dynamic self-consistent field simulations. %0 journal article %@ 1022-1352 %A Kricheldorf, H.R.,Lossow, C.v.,Schwarz, G.,Fritsch, D. %D 2005 %J Macromolecular Chemistry and Physics %N %P 1165-1170 %R doi:10.1002/macp.200400509 %T Chain Extension and Cyclization of Telechelic Polysarcosines %U https://doi.org/10.1002/macp.200400509 %X Sarcosine N-carboxyanhydride (Sar-NCA) was,polymerized with 1,12-diaminododecane (DAD) or 1,13-,diamino-4,7,10-trioxatridecane (DATT) as initiators, and,telechelic blocks having two secondary amino endgroups,were obtained. Their structure was proven by 1H NMR and,MALDI-TOF mass spectrometry. The SEC measurements,indicated narrow molecular weight distribution with polydispersity,indices in the range of 1.1–1.2. These difunctional,polysarcosines were reacted with three different coupling,agents: 4,40-diisocyanatodiphenylmethane (MDI), N-hydroxysuccinimide,sebacate, and sebacoyl bisimidazolide. Although,the 1H NMR spectra proved high conversions, only a,moderate chain extension was observed. The MALDI-TOF,mass spectra indicated a high extent of cyclization, which,limited the chain growth. %0 journal article %@ 0887-6266 %A Prado, L.A.S.de A.,Goerigk, G.,Ponce, M.,Haramus, V.,Willumeit, R.,Wittich, H.,Schulte, K.,Pereira Nunes, S. %D 2005 %J Journal of Polymer Science B %N 21 %P 2981-2992 %R doi:10.1002/polb.20576 %T Characterization of Proton-Conducting Organic–Inorganic Polymeric Materials by ASAXS %U https://doi.org/10.1002/polb.20576 21 %X The distribution of ZrO2 and phosphotungstic acid (PTA) in a matrix of sulfonated polyether ketone was investigated by anomalous small-angle X-ray scattering (ASAXS). Scattering curves were obtained using X-ray energies near the Zr and W absorption edges, allowing the independent analysis of the distribution of ZrO2 and PTA in the sample. The interaction between both inorganic components improved their dispersion considerably when compared with films containing just one of the additives. The synergism was correlated to previous investigations concerning proton conductivity and permeability of the membranes developed for direct methanol fuel cell. %0 journal article %@ 0920-5861 %A Silva, V.,Ruffmann, B.,Vetter, S.,Mendes, A.,Madeira, L.,Pereira Nunes, S. %D 2005 %J Catalysis Today %N 2-4 %P 205-212 %R doi:10.1016/j.cattod.2005.03.051 %T Characterization and application of composite membranes in DMFC %U https://doi.org/10.1016/j.cattod.2005.03.051 2-4 %X The present work focuses on the characterization of membranes for direct methanol fuel cells (DMFC), prepared using composites of,sulfonated poly(ether ether ketone) (sPEEK, with sulfonation degree, SD, of 42 and 68%) as polymer matrix. This polymer was inorganically,modified incorporating different amounts of zirconium phosphate (ZrPh) pretreated with n-propylamine and polybenzimidazole (PBI). The investigated properties were: proton conductivity, water and aqueous methanol swelling, permeability coefficients for DMFC species and morphology. DMFC tests were performed at 110 8C with relative humidity (r.h.) in the cathode feed of 100 and 138%. The results obtained show that the inorganic modification of the polymer decreases the proton conductivity, water and aqueousmethanol swelling and permeability towards DMFC species. In terms of morphology, it was found that the applied procedure enabled the preparation of membranes with good compatibility between inorganic and organic components. In terms of theDMFCtests of the compositemembranes, working with the cathode feed at 100%r.h.,,the unmodified sPEEKmembrane with SD = 42%proved to have the best performance, althoughwith higher methanol crossover. In contrast, for r.h. of 138%, the best performancewas achieved by the sPEEKcomposite membrane with SD = 68 and 20.0 wt.% of ZrPh and 11.2 wt.% of PBI. %0 journal article %@ 0378-7753 %A Silva, V.S.,Ruffmann, B.,Silva, H.,Gallego, Y.A.,Mendes, A.,Madeira, L.M.,Pereira Nunes, S. %D 2005 %J Journal of Power Sources %N 1 %P 34-40 %R doi:10.1016/j.jpowsour.2004.08.004 %T Proton electrolyte membrane properties and direct methanol fuel cell performance - I. Characterization of hybrid sulfonated poly(ether ether ketone)/zirconium oxide membranes %U https://doi.org/10.1016/j.jpowsour.2004.08.004 1 %X This paper presents an evaluation of the zirconium oxide effects in sulfonated poly(ether ether ketone) (sPEEK) with sulfonation degree,(SD) of 87%. A series of inorganic–organic hybrid membranes were prepared with a systematic variation of the zirconium oxide content,via in situ zirconia formation (2.5, 5.0, 7.5, 10, 12.5 wt.%). This procedure enabled the preparation of proton electrolyte membranes (PEM) with a wide range of properties, which can be useful for evaluating the relationship between the PEM properties and the direct methanol fuel cell (DMFC) performance. The investigated properties are the proton conductivity, proton transport resistance, water uptake, water,,methanol, oxygen, carbon dioxide and nitrogen permeability coefficients, morphology and elemental analysis. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is found that it leads also to a decrease of the water, methanol, carbon dioxide and oxygen permeability coefficients, an increase of the water/methanol selectivity and a decrease of the carbon dioxide/nitrogen and oxygen/nitrogen selectivities. In terms of morphology, it is found that in situ zirconium alkoxide hydrolysis enables the preparation of homogeneous membranes that present a good adhesion between inorganic domains and the polymer matrix. %0 journal article %@ 0378-7753 %A Silva, V.S.,Schirmer, J.,Reissner, R.,Ruffmann, B.,Silva, H.,Mendes, A.,Madeira, L.M.,Pereira Nunes, S. %D 2005 %J Journal of Power Sources %N 1 %P 41-49 %R doi:10.1016/j.jpowsour.2004.08.012 %T Proton electrolyte membrane properties and direct methanol fuel cell performance - II. Fuel cell performance and membrane properties effects %U https://doi.org/10.1016/j.jpowsour.2004.08.012 1 %X In order to study the relationship between the properties of proton electrolyte membranes (PEMs), obtained through standard characterization methods, and the direct methanol fuel cell (DMFC) performance, inorganic–organic hybrid membranes, modified via in situ hydrolysis, were used in a membrane electrolyte assembly (MEA) for DMFC application. The membranes, the characterization of which was performed in the previous paper of this series, were based on sulfonated poly(ether ether ketone) (sPEEK) with a sulfonation degree (SD) of 87% and were loaded with different amounts of zirconium oxide (5.0, 7.5, 10.0, 12.5 wt.%). The standard characterization methods applied were impedance spectroscopy (proton conductivity), water uptake, and pervaporation (permeability to methanol). The MEAs were characterized investigating the DMFC current–voltage polarization curves, constant voltage current (CV, 35 mV), and open-circuit voltage (OCV). The fuel cell ohmic resistance (null phase angle impedance, NPAI) and CO2 concentration in the cathode outlet were also measured. The characterization results show that the incorporation of the inorganic oxide in the polymer network decreases the DMFC current density for CV experiments, CO2 concentration in the cathode outlet for both OCV and CV experiments and, finally, the maximum power density output. The opposite effectwas verified in terms of the NPAI (ohmic resistance) for both OCV and CV experiments. A good agreement was found between the studied DMFC performance parameters and the characterization results evaluated by impedance spectroscopy, water uptake and pervaporation experiments. %0 journal article %@ 0014-3057 %A Karthikeyan, C.S.,Pereira Nunes, S.,Schulte, K. %D 2005 %J European Polymer Journal %N 6 %P 1350-1356 %R doi:10.1016/j.eurpolymj.2004.12.011 %T Ionomer-silicates composite membranes: Permeability and conductivity studies %U https://doi.org/10.1016/j.eurpolymj.2004.12.011 6 %X Polymer composite membranes based on sulphonated polymers, such as sulphonated poly(ether ketone) and sulphonated poly(ether ether ketone), and silicates were prepared and characterized for water/methanol permeabilities and proton conductivity studies. The study showed methanol and water permeability in the composite system decreased, with respect to the plain polymer/ionomer, with the increase in content of silicates. The permeability reduction in the composite membranes is discussed using models and theories. It was also found that the proton conductivity of the ionomer-composite membranes increased with the increase in total flux of the system, emphasising a good correlation,between the total flux of the composite membranes and proton conductivity. The work clearly demonstrates that the same transport mechanism governs both methanol–water crossover and proton conductivity in these polymer,electrolyte composite membranes. %0 journal article %@ 0167-2738 %A Roeder, J.,Silva, H.,Pereira Nunes, S.,Pires, A. %D 2005 %J Solid State Ionics %N 15-16 %P 1411-1417 %R doi:10.1016/j.ssi.2005.03.008 %T Mixed conductive blends of SPEEK/PANI %U https://doi.org/10.1016/j.ssi.2005.03.008 15-16 %X Membranes were obtained by solvent evaporation from 70% sulfonated poly(ether ether ketone) and polyaniline in N-methyl-2-pyrrolidone [NMP] or N,N-dimethyl formamide [DMF]. SPEEK/PANI membranes were studied by UV–Vis spectroscopy, ion-exchange capacity, ionic and electronic conductivity and thermal properties, in order to observe the SPEEK doping effect and the solvent influence on the system. The protonation degree obtained, by elemental analysis and ion-exchange capacity, showed that almost 85 wt.% (in DMF) and 95 wt.% (in NMP) of SPEEK is required in order to obtain a 56% PANI protonation degree. The UV–Vis spectroscopy of the system in solution gave similar results. Electronic conductivity is in the order of 10− 6 S cm− 1 and the protonic conductivity values were high, in the order of magnitude useful for electrochemical devices, like fuel cells. All the SPEEK/PANI sample blends were stable up to 230 °C and the char residue at 700 °C is proportional to the component quantities. The temperatures up to which the blends were stable were up to 20 °C higher than those for SPEEK. %0 journal article %@ 0376-7388 %A Karthikeyan, C.S.,Pereira Nunes, S.,Prado, L.,Ponce, M.,Silva, H.,Ruffmann, B.,Schulte, K. %D 2005 %J Journal of Membrane Science %N 1-2 %P 139-146 %R doi:10.1016/j.memsci.2004.12.048 %T Polymer Nanocomposite Membranes for DMFC application %U https://doi.org/10.1016/j.memsci.2004.12.048 1-2 %X Polymer nanocomposite membranes based on sulphonated poly(ether ether ketone) (SPEEK) containing different weight percentages of synthetic non-spherical nanofillers such as laponite and MCM-41 were prepared and characterised for direct methanol fuel cells (DMFC). Prior to the preparation of the composite membranes, they were modified using organo silanes. The results showed that there was a decrease in methanol and water permeability with the increasing content of modified laponite and MCM-41. While the membranes containing higher (>10) weight percentages of silicates displayed lower proton conductivity values than plain polymer, the lower percentages even showed better values than the plain. The results are compared with the membranes containing spherical nanofillers, namely Aerosil and an isotropic silica network system in order to see the effect of shape of nanofillers on the properties of the composite membranes. Among all shapes, membranes containing silica network had the lowest permeability but they also had poor conductivity values. Much more evident than the effect of form or aspect was the influence of the filler surface modification. In all the cases, organic modification drastically decreased methanol and water permeabilities. A good agreement between the experiment and theory was found for the permeability reduction for membranes containing lower weight percentages of layered silicates assuming aspect ratio of 125 for laponite. %0 journal article %@ 0376-7388 %A Vetter, S.,Ruffmann, B.,Buder, I.,Pereira Nunes, S. %D 2005 %J Journal of Membrane Science %N 1-2 %P 181-186 %R doi:10.1016/j.memsci.2005.02.036 %T Proton conductive membranes of sulfonated poly(ether ketone ketone) %U https://doi.org/10.1016/j.memsci.2005.02.036 1-2 %X Poly(ether ketone ketone) was sulfonated using fumic sulfuric acid and used for preparation of proton conductive membranes. The sulfonation degree was evaluated by elemental and thermal analysis and the IEC values were determined by titration. The proton conductivity of membranes with sulfonation degrees up to 70% was determined as a function of temperature by impedance spectroscopy. Membranes with sulfonation degree 38–70% were tested in DMFC experiments. Their performance was comparable to Nafion® with the same pretreatment and clearly better than sulfonated poly(ether ether ketone) membranes with similar functionalization. The methanol crossover was lower than that of Nafion® in the same conditions. %0 journal article %@ 0022-3093 %A Prado, L.A.S.de A.,Karthikeyan, C.S.,Schulte, K.,Pereira Nunes, S.,Torriani, I.L. %D 2005 %J Journal of Non-Crystalline Solids %N 12-13 %P 970-975 %R doi:10.1016/j.jnoncrysol.2004.12.007 %T Organic modification of layered silicates: structural and thermal characterizations %U https://doi.org/10.1016/j.jnoncrysol.2004.12.007 12-13 %X Organic modification of natural and synthetic layered silicates namely montmorillonite and laponite is reported in this work. The modified silicates are being subsequently used in the preparation of nano-composite membranes based on ionomers for fuel cells application. Laponite, an entirely synthetic silicate, was modified using organosiloxanes containing imidazole groups. Two different strategies were adopted for modification: (a) swelling of the silicate in 2-butanone followed by functionalization using the siloxane at room temperature, (b) direct reaction between laponite and the organosiloxane in xylene at 120 °C. Montmorillonite, a natural silicate, was supplied in the alkyl-ammonium form containing –OH groups. The modification of this silicate was conducted following the procedure (b). The structures of both plain and modified silicates were investigated by XRD showing that the interlayer distance (around 17 Angstrom capital A, ring) was not affected during the functionalization of laponite. However, a noticeable increase in the interlayer distance from 18.0 Angstrom capital A, ring to 24.5 Angstrom capital A, ring was observed for the modified montmorillonite. This clearly shows the presence of polysiloxane chains in between the silicate layers. Further characterization showed that the modification of these silicates was in the range between 16% and 23% (molar percentage). TGA was done between 25 and 300 °C in order to study the thermal degradation pattern of the silicates. The amount of adsorbed water could be determined from the results. The functionalization reduced the adsorption of water from 13.5% to 6.8% for laponite and from 8.5% to 4% for montmorillonite. %0 journal article %@ 0378-7753 %A Vasco, S.,Weisshaar, S.,Reissner, R.,Ruffmann, B.,Vetter, S.,Mendes, A.,Madeira, L.,Pereira Nunes, S. %D 2005 %J Journal of Power Sources %N 2 %P 485-494 %R doi:10.1016/j.jpowsour.2004.12.061 %T Performance and efficiency of a DMFC using non-fluorinated compositemembranes operating at low/medium temperatures %U https://doi.org/10.1016/j.jpowsour.2004.12.061 2 %X In order to increase the chemical/thermal stability of the sulfonated poly(ether ether ketone) (sPEEK) polymer for direct methanol fuel cell (DMFC) applications at medium temperatures (up to 130 °C), novel inorganic–organic composite membranes were prepared using sPEEK polymer as organic matrix (sulfonation degree, SD, of 42 and 68%) modified with zirconium phosphate (ZrPh) pretreated with n-propylamine and polybenzimidazole (PBI). The final compositions obtained were: 10.0 wt.% ZrPh and 5.6 wt.% PBI; 20.0 wt.% ZrPh and 11.2 wt.% PBI. These composite membranes were tested in DMFC at several temperatures by evaluating the current–voltage polarization curve, open circuit voltage (OCV) and constant voltage current (CV, 35 mV). The fuel cell ohmic resistance (null phase angle impedance, NPAI) and CO2 concentration in the cathode outlet were also measured. A method is also proposed to evaluate the fuel cell Faraday and global efficiency considering the CH3OH, CO2, H2O, O2 and N2 permeation through the proton exchange membrane (PEM) and parasitic oxidation of the crossover methanol in the cathode. In order to improve the analysis of the composite membrane properties, selected characterization results presented in [V.S. Silva, B. Ruffmann, S. Vetter, A. Mendes, L.M. Madeira, S.P. Nunes, Catal. Today, in press] were also used in the present study. The unmodified sPEEK membrane with SD = 42% (S42) was used as the reference material. In the present study, the composite membrane prepared with sPEEK SD = 68% and inorganic composition of 20.0 wt.% ZrPh and 11.2 wt.% PBI proved to have a good relationship between proton conductivity, aqueous methanol swelling and permeability. DMFC tests results for this membrane showed similar current density output and higher open circuit voltage compared to that of sPEEK with SD = 42%, but with much lower CO2 concentration in the cathode outlet (thus higher global efficiency) and higher thermal/chemical stability. This membrane was also tested at 130 °C with pure oxygen (cathode inlet) and achieved a maximum power density of 50.1 mW cm−2 at 250 mA cm−2. %0 journal article %@ 0009-286X %A Brinkmann, T.,Wind, J.,Ohlrogge, K. %D 2004 %J Chemie - Ingenieur - Technik %N 11 %P 1607-1611 %T Membranverfahren in der Erdgasaufbereitung %U 11 %X %0 journal article %@ 0376-7388 %A Ebert, K.,Fritsch, D.,Koll, J.,Tjahjawiguna, C. %D 2004 %J Journal of Membrane Science %N 1-2 %P 71-78 %T Influence of inorganic fillers on the compaction behaviour of porous polymer based membranes %U 1-2 %X %0 journal article %@ 1385-8947 %A Brandao, L.,Fritsch, D.,Madeira, L.M.,Mendes, A.M. %D 2004 %J Chemical Engineering Journal %N 1-3 %P 89-97 %R doi:10.1016/j.cej.2004.07.008 %T Kinetics of Propylene Hydrogenation on Nanostructured Palladium Clusters %U https://doi.org/10.1016/j.cej.2004.07.008 1-3 %X %0 journal article %@ 1618-7229 %A Abetz, V.,Jiang, S. %D 2004 %J e-Polymers %N 1 %P 54 %R doi:10.1515/epoly.2004.4.1.599 %T Formation of superlattices in blends of 3-miktoarm star terpolymers with diblock copolymers %U https://doi.org/10.1515/epoly.2004.4.1.599 1 %X In this contribution we report on the morphological structures formed in blends of microphase-separated 3-miktoarm star terpolymers of polystyrene-armpolybutadiene- arm-poly(2-vinylpyridine) (SBV*) and polystyrene-block-polybutadiene (SB), polystyrene-block-poly(2-vinylpyridine) (SV), poly(2-vinylpyridine)- block-poly(cyclohexyl methacrylate) (VC) diblock copolymers. The morphologies are characterized by transmission electron microscopy. Blends with similar morphologies as known from linear triblock terpolymers are found, like core-shell structures based on cylinders or gyroids. Other blends show very distorted morphologies, or morphologies similar to the ones found for pure 3-miktoarm star terpolymers. While attractive interactions between blocks of the two species enhance the formation of common superlattices, blends with too large diblock copolymers tend to macrophase-separate. %0 journal article %@ 0009-286X %A Brinkmann, T.,Ebert, K.,Pingel, H.,Wenzlaff, A.,Ohlrogge, K. %D 2004 %J Chemie - Ingenieur - Technik %N 10 %P 1529-1533 %T Prozessalternativen durch den Einsatz organisch-anorganischer Kompositmembranen fuer die Dampfpermeation %U 10 %X %0 journal article %@ 0255-2701 %A Bengtson, G.,Fritsch, D.,Oehring, M. %D 2004 %J Chemical Engineering and Processing %N 9 %P 1159-1170 %T Improved dense catalytically active polymer membranes of different configuration to separate and react organics simultaneously by pervaporation %U 9 %X %0 journal article %@ 1381-5148 %A Vetter, S.,Pereira Nunes, S. %D 2004 %J Reactive and Functional Polymers %N 2 %P 171-182 %R doi:10.1016/j.reactfunctpolym.2004.05.002 %T Synthesis and characterization of new sulfonated poly(arylene ether 1,3,4-oxadiazole)s %U https://doi.org/10.1016/j.reactfunctpolym.2004.05.002 2 %X %0 journal article %@ 0011-9164 %A Ponce, M.L.,Prado, L.A.S.de A.,Silva, V.,Pereira Nunes, S. %D 2004 %J Desalination %N %P 383-391 %T Membranes for direct methanol fuel cell based on modified heteropolyacids %U %X %0 journal article %@ 0376-7388 %A Ponce, M.L.,Prado, L.,Ruffmann, B.,Richau, K.,Mohr, R.,Pereira Nunes, S. %D 2003 %J Journal of Membrane Science %N %P 5-15 %T Reduction of Methanol Permeability in Polyetherketone-Heteropolyacid Membranes %U %X %0 journal article %@ 1438-7492 %A Karthikeyan, C.S.,Schossig, M.,Radovanovic, E.,Goncalves, M.C.,Wittich, H.,Schulte, K.,Pereira Nunes, S. %D 2003 %J Macromolecular Materials and Engineering %N 2 %P 175-180 %T Aligned Nafion nanocomposites: preparation and morphological characterization %U 2 %X %0 journal article %@ 1022-1352 %A Jakoby, K.,Peinemann, K.-V.,Pereira Nunes, S. %D 2003 %J Macromolecular Chemistry and Physics %N 1 %P 61-67 %R doi:10.1002/macp.200290066 %T Palladium-Catalyzed Phosphonation of Polyphenylsulfone %U https://doi.org/10.1002/macp.200290066 1 %X %0 journal article %@ 0920-5861 %A Fritsch, D.,Kuhr, K.,Mackenzie, K.,Kopinke, F.-D. %D 2003 %J Catalysis Today %N 1-4 %P 105-118 %R doi:10.1016/S0920-5861(03)00208-6 %T Hydrodechlorination of Chloroorganic Compounds in Ground Water by Palladium Catalysts - PART 1. Development of polymer-based catalysts and membrane reactor tests %U https://doi.org/10.1016/S0920-5861(03)00208-6 1-4 %X %0 journal article %@ 0268-2575 %A Brinkmann, T.,Dijkstra, M.,Ebert, K.,Ohlrogge, K. %D 2003 %J Journal of Chemical Technology and Biotechnology %N 2-3 %P 332-337 %T Improved simulation of a Vapour permeation module %U 2-3 %X %0 journal article %@ 0167-2738 %A Ruffmann, B.,Silva, H.,Schulte, B.,Pereira Nunes, S. %D 2003 %J Solid State Ionics %N %P 269-275 %T Organic/inorganic composite membranes for application in DMFC %U %X %0 journal article %@ 0077-8923 %A Brinkmann, T.,Ohlrogge, K. %D 2003 %J Annals of the New York Academy of Sciences %N %P 306-317 %T Natural Gas clean-Up by means of Membranes %U %X %0 journal article %@ 0276-7333 %A Anupama, D.,Ebert, K.,Plenio, H. %D 2003 %J Organometallics %N 23 %P 4685-4691 %R doi:10.1021/om0303754 %T Nanofiltration for Homogeneous Catalysis Separation: Soluble polymer-supported Pd-catalysts for Heck, Sonogashira- and Suzuki Coupling of Aryl Chlorides and Bromides %U https://doi.org/10.1021/om0303754 23 %X %0 journal article %@ 0024-9297 %A Kricheldorf, H.R.,Fritsch, D.,Vakhtangishvili, L.,Schwarz, G. %D 2003 %J Macromolecules %N 12 %P 4337-4344 %T Multicyclic Poly(ether sulfone)s of Phloroglucinol Forming Branched and Cross-linked Architectures %U 12 %X %0 journal article %@ 0009-286X %A Dijkstra, M.F.J.,Bach, S.,Brinkmann, T.,Ebert, K.,Ohlrogge, K. %D 2003 %J Chemie - Ingenieur - Technik %N 11 %P 1611-1616 %T Hybridverfahren zur Trennung von Methanol/Isopropanol/Wasser-Gemischen %U 11 %X %0 journal article %@ 1022-1352 %A Gomes, D.,Pereira Nunes, S. %D 2003 %J Macromolecular Chemistry and Physics %N 17 %P 2130-2141 %T Synthesis and Characterization of Poly(arylene ether oxadiazole) Telechelic %U 17 %X %0 journal article %@ 0892-7022 %A Gomes, D.,Pereira Nunes, S.,Pinto, J.C.,Borges, C. %D 2003 %J Polymer %N %P 3633-3639 %T Synthesis and Characterization of Flexible Polyoxadiazole Films through Cyclodehydration of Polyhydrazides %U %X %0 journal article %@ 0021-8995 %A Dyck, A.,Fritsch, D.,Pereira Nunes, S. %D 2002 %J Journal of Applied Polymer Science %N 11 %P 2820-2827 %T Proton-conductive membranes of sulfonated polyphenylsulfone %U 11 %X %0 journal article %@ 0011-9164 %A Randjelovic, I.,Bengtson, G.,Fritsch, D. %D 2002 %J Desalination %N %P 417-418 %T Catalytic Membranes: Alkene Dimerisation by means of Acidic Porous Thin-film Composite Membranes %U %X %0 journal article %@ 1060-1325 %A Fritsch, D.,Vakhtangishvili, L.,Kricheldorf, H.R. %D 2002 %J Journal of Macromolecular Science A %N 11 %P 1335-1347 %T Syntheses and Functionalization of Poly(ether sulfone)s based on 1,1,1-Tris(4-hydroxyphenyl)ethane %U 11 %X %0 journal article %@ 0887-624X %A Kricheldorf, H.R.,Vakhtangishvili, L.,Fritsch, D. %D 2002 %J Journal of Polymer Science A %N 17 %P 2967-2978 %T Syntheses and Functionalization of Poly(ether sulfone)s based on 1,1,1-Tris(4-hydroxyphenyl)ethane %U 17 %X %0 journal article %@ 0009-286X %A Ohlrogge, K.,Herbst, M.,Scheel, H.,Wind, J.,Peinemann, K.-V. %D 2002 %J Chemie - 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