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Asymmetric block copolymer membranes can be facilely prepared via non-solvent induced phase separation combined with self-assembly. The membrane is characterized by a thin layer of highly ordered and uniform cylindrical nano-channels on top of a non-ordered macroporous sponge-like layer. Up to date, most studies concerning block copolymer membranes are focused on separation applications. In this work, highly adsorptive and adhesive isoporous block copolymer membranes have been fabricated. Because of the functionalization with cyclodextrin, the membrane shows excellent affinity to guest molecules. Moreover, the membrane is biocompatible and is adhesive to various substrates (e.g. glass, silicon, gold and stainless steel). Triclosan as a model drug was utilized to demonstrate the applicability of the membranes as a drug reservoir. A high loading capacity (305.5 μg cm−2) was achieved. The release behavior was investigated under various pH values in vitro. A long-time extended drug release was achieved without showing an initial burst effect. Furthermore, pH-responsive release behavior was observed. The triclosan-loaded membrane exhibited a significant antibacterial effect due to the triclosan release; the diffusion out of the membrane was evaluated using a disc diffusion assay. This study provides great potential for isoporous block copolymer membranes as a delivery platform for a wide variety of biomedical applications.

Water vapor removal is a crucial process for several industries (e.g., air conditioning systems, flue gas dehydration, compressed air drying etc.). An effective dehumidification has the potential to drastically reduce the energy consumption and the overall cost of a process stream. Membranes with high water permeance and selectivity are promising candidates to achieve an energy-efficient water removal. We propose self-assembled membranes with interconnected and ordered hydrophilic domains that act as extremely fast water transport highways (water channels). We used a commercial amphiphilic pentablock copolymer (Nexar™), which has the ability to form long-range, self-ordering nanoscale morphologies with rigid end-blocks and a flexible molecular network where polar and non-polar solvents regulated the final morphologies of the membranes. Our results demonstrate how well-defined periodic morphology allow for molecular level control in effective removal of water vapor. The membranes with ordered hydrophilic nanochannels present a 6-fold improvement in water vapor permeability and a 14-fold increase in water vapor/N2 selectivity compared to Nexar™ membranes with disordered domains. Molecular dynamics stimulations are carried out on the self-assembly behavior of block copolymer solution in different solvents. In addition, sorption and desorption kinetics studies for Nexar™ films were correlated to the different morphologies imaged by transmission electron, atomic force and environmental scanning electron microscopy.

In this work, a novel thin-film composite membrane composed of a polyester film on a cellulose support was successfully synthesised. The polyester film was formed from the interfacial reaction between catechin, a bio-derived poly-phenol, and terephthaloyl chloride (TPC). The cellulose support was prepared by non-solvent induced phase separation from a 12.5 wt% cellulose dope solution in 1-ethyl-3-methylimidazolium acetate ionic liquid. The composite membrane was characterised by Fourier Transform Infrared and X-Ray Photoelectron Spectroscopy to confirm the success of the interfacial reaction. Scanning electron and atomic force microscopy were used to study the surface morphology and roughness of the membranes produced. The performance of the composite membranes in terms of solvent permeance and solute rejection was investigated by studying the rejection of a broad range of different molecular weight dyes in dimethylformamide (DMF) solution. The membranes showed an average DMF permeance of 1.2 L m−2 h−1 bar−1 with a molecular weight cut-off of around 500 g mol−1. The membrane was stable in DMF over 30 days with no significant change in performance. The membrane has potential application in the food and pharmaceutical industries.

Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block. Hybrid polyamide films are formed by interfacial polymerization of 5,10,15,20-(tetra-4-aminophenyl)porphyrin/m-phenylene diamine (MPD) mixtures with trimesoyl chloride. Porphyrin is a non-planar molecule, containing a heterocyclic tetrapyrrole unit. Its incorporation into a polyamide film leads to higher free volume than that of a standard polyamide film. Polyamide films derived from porphyrin and MPD amines with a fixed total amine concentration of 1 wt% and various porphyrin/MPD ratios were fabricated and characterized. The porphyrin/MPD polyamide film was complexed with Cu(II), due to the binding capacity of porphyrin to metal ions. By coupling scanning transmission electron microscopy (STEM) with electron energy-loss spectroscopy (EELS), Cu mapping was obtained, revealing the distribution of porphyrin in the interfacial polymerized layer. By using porphyrin as amine-functionalized monomer a membrane with thin selective skin and enhanced solvent transport is obtained, with good dye selectivity in the nanofiltration range. For instance, an ultra-fast hexane permeance, 40-fold increased, was confirmed when using 0.5/0.5 porphyrin/MPD mixtures, instead of only MPD as amine monomer. A rejection of 94.2% Brilliant Blue R (826 g/mol) in methanol was measured.

A unique method for the preparation of cellulose-polyethyleneimine (PEI) blend membranes for nanofiltration is presented. Trimethylsilyl cellulose was used as a precursor for the blend membrane fabrication followed by a simple hydrolysis to regenerate the cellulose structure. The resulting homogeneous blend membranes exhibited high neutral solute rejection in water, which was surprisingly better than the performance of the individual membranes due to the strong interactions between the blended polymers. More interestingly, the same membrane demonstrated over five times higher flux of methanol after solvent activation with water as compared to the fluxes of the pure membranes, attributed to formation of nanocracks. High rejection of negatively charged dyes in this solvent with around 450 Da molecular weight cut-off was obtained at an exceptionally high flux of 160 Lm−2 h−1 at a pressure of 4.5 bar. The membranes will be beneficial in nanofiltration of polar solvents containing neutral and charged molecules.

In this work we demonstrate the successful optimization of the interfacial polymerization reaction for the manufacture of organic solvent nanofiltration membranes by replacing the toxic amines commonly used for this method with the natural occurring bio-polyphenol morin. For the manufacture of this type of OSN membrane a crosslinked PAN support was coated by interfacial polymerization using morin as the monomer of the aqueous phase and terephthaloyl chloride as the monomer of the organic phase. These membranes showed an exceptional performance and resistance to NMP by having a permeance of 0.3 L/m2 h bar in NMP with a rejection of 96% of Brilliant Blue dye which has a molecular weight of 825.97 g/mol, making these membranes attractive for harsh industrial separation processes due to their ease of manufacture, low cost, and excellent performance.

The natural oligomer tannic acid was used as a reactant for an interfacial polymerization on top of a crosslinked polyacrylonitrile (PAN) membrane. The PAN membrane was soaked with the aqueous tannic acid solution and contacted with a dilute solution of teraphtaloyl chloride in hexane. Since both layers, the PAN support and the thin tannin-based layer, are highly crosslinked, the resulting thin film composite membrane is stable in harsh solvent environments such as N-Methyl-2-pyrrolidone (NMP). NMP permeances of up to 0.09 L/m 2 h bar with a molecular weight cut-off of approximately 800 g/mol were obtained. The exceptional stability in NMP and the incorporation of natural compounds like tannic acid for the manufacture of organic solvent nanofiltration membranes provides a cost-effective alternative for industrial separations due to the simplicity of the interfacial reaction and the replacement of the commonly applied toxic aromatic amines. The scale up of the manufacturing process is not difficult; the low price of the natural tannic acid is another advantage.

The major challenge in membrane filtration is fouling which reduces the membrane performance. Fouling is mainly due to the adhesion of foulants on the membrane surfaces. In this work, we studied the fouling behavior of polystyrene- b -poly(4-vinylpyridine) (PS- b -P4VP) isoporous membrane and the mussel inspired polydopamine/ L -cysteine isoporous zwitterionic membrane. Polystyrene- b -poly(4-vinylpyridine) (PS- b -P4VP) isoporous membranes were fabricated via self-assembly and non-solvent induced phase separation method. Subsequently, the isoporous membrane was modified by a mild mussel-inspired polydopamine (PDA) coating; the isoporous surface structure and the water flux was retained. Zwitterionic L -cysteine was further anchored on the PDA coated membranes via Michael addition reaction at pH 7 and 50 °C to alleviate their antifouling ability with foulants solution. The membranes were thoroughly characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and zeta potential measurements. Contact angle and dynamic scanning calorimetry (DSC) measurements were carried out to examine the hydrophilicity. The pH-responsive behavior of the modified membrane remains unchanged and antifouling ability after PDA/ L -cysteine functionalization was improved. The modified and unmodified isoporous membranes were tested using humic acid and natural organic matter model solutions at 0.5 bar feed pressure.

In this study composite mixed matrix membranes containing hydrophilic microphase-separated block copolymer (Pebax ® 1657) and graphene oxide nanosheets were prepared using a dip coating method. Water vapor and N 2 gas permeation were measured as a function of different parameters: (i) layer thickness, (ii) content of graphene oxide (GO), and (iii) content of reduced GO. Surprisingly, a concentration of only 2 wt% of GO nanosheets well dispersed in the Pebax layer boosted the selectivity 8 times by decreasing the water vapor permeance by only 12% whereas N 2 gas permeance decreased by 70%. Using reduced GO instead, the water vapor permeance declined by up to 16% with no influence on the N 2 gas permeance. We correlated the permeation properties of the mixed matrix membranes with different models and found, that both the modified Nielsen model and the Cussler model give good correlation with experimental findings.

Poly(ether block amide) – Pebax® – based membranes are well described for gas separation applications. But only a few publications exist for their application in pressure driven liquid applications like ultrafiltration and nanofiltration. Here we use the commercially available Pebax® 1657 for the preparation of membranes for the filtration of organic solvents. Porous polyacrylonitrile membranes were coated with Pebax® 1657 which was then crosslinked. Toluene diisocyanate (TDI) was used as a crosslinker agent for the coating. Reaction time and crosslinker concentration were optimized for the aimed application. The Pebax® coating and the impact of the TDI on the resulting crosslinked membranes were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). SEM analysis shows a uniform thin coating of the PEBAX that covers the pores of the PAN membranes. FTIR and DSC analysis confirm the crosslinking reaction. Crosslinked Pebax® membranes show high stability toward ethanol propanol, acetone and even dimethylformamide (DMF). In the case of DMF applications, the standard PAN was replaced by crosslinked PAN developed in our laboratory. In order to increase the membranes permeances, graphene oxide (GO) nanosheets were incorporated in the Pebax® coating. These GO containing membranes showed strongly increased permeances for selected solvents.

Recently isoporous block copolymer (BCP) membranes obtained by non-solvent induced phase separation gained a lot of attention due to their highly ordered surface layer, high flux and superior separation properties. These polystyrene-b-poly-4-vinylpyridine (PS-b-P4VP) based membranes showed a strong flux dependence of pH; pores closed at low pH and opened at high pH. The pH-response could now be reversed by a simple post modification; pores are now opening at low pH and closing at high pH. The original membrane was transformed into a polyanionic pH responsive membrane in a one step chemical modification without affecting the isoporous surface morphology. A polystyrene-b-poly-4-vinylpyridine-N-oxide (PS-b-P4VPN-oxide) membrane is obtained by selective oxidation of the PS-b-P4VP membrane. The in situ generated peracid obtained by reacting acetic acid and hydrogen peroxide is employed for oxidation. Surprisingly not only the asymmetric membrane structure with the isoporous skin was retained, but also the mechanical and chemical membrane stability was improved significantly. The modified membranes are insoluble in solvents like DMF, NMP and DMSO. Two kinds of PS-b-P4VP based isoporous membranes are available now with reverse flux response to pH. This opens the door to new interesting charge based fractionations.

In this study, green bio-membranes were investigated. Alginate membranes were prepared by crosslinking of sodium alginate in calcium chloride aqueous solution. By fabricating membranes simply using three abundant cheap materials i.e. sodium alginate, salt and water, we have demonstrated membranes with acceptable performance for OSN with excellent chemical stability. Membranes prepared on three different polymeric supports (PAN, crosslinked PAN and Cellulose) showed similar performance. The alginate membranes were also spun coated on glass plate and laminated on alumina support. Great chemical stability was observed towards various solvents including dimethylformamide and dimethylsulfoxide. Characterization tests with FTIR, SEM, AFM and contact angle were carried out. Using same support, many parameters were explored such as the alginate concentration and the post treatment such as drying, crosslinking or precipitating in non-solvent. The range of the membranes permeance was 0.08–1.8 L/m2 h bar depending on conditions used. The nanofiltration experiments revealed a molecular weight cut off of about 1200 g/mol when tested with dyes such as Methyl Orange, Brilliant Blue and vitamin B12 in methanol. We initiated the preparation of fully green organic solvent nanofiltration membranes using green routes by preparing alginate selective layer on top of cellulose support. This study demonstrates that alginate membranes can be a promising candidate for green organic solvent nanofiltration.

We report a new synthetic route of fabricating regenerated cellulose nanofiltration membranes. The membranes are composite membranes with a thin selective layer of cellulose, which was prepared by regeneration of trimethylsilyl cellulose (a hydrophobic cellulose derivative) film followed by crosslinking. Filtration experiments using mixtures of sugar and sodium chloride showed that solutes above 300 Da were highly rejected whereas practically no rejection was observed for NaCl. This is a big advantage for a complete desalination as the existing commercial nanofiltration membranes typically exhibit NaCl rejection in the range of 30–60%. Membranes with zero NaCl rejection are required for recovery and purification applications in food, chemical and pharmaceutical industry.

Nanostructured block copolymer membranes were manufactured by water induced phase inversion, using ionic liquids (ILs) as cosolvents. The effect of ionic liquids on the morphology was investigated, by using polystyrene-b-poly(4-vinyl pyridine) (PS-b-PV4P) diblock as membrane copolymer matrix and imidazolium and pyridinium based ILs. The effect of IL concentration and chemical composition was evident with particular interaction with P4VP blocks. The order of block copolymer/ILs solutions previous to the membrane casting was confirmed by cryo scanning electron microscopy and the morphologies of the manufactured nanostructured membranes were characterized by transmission and scanning electron microscopy. Non-protic ionic liquids facilitate the formation of hexagonal nanoporous block copolymer structure, while protic ILs led to a lamella-structured membrane. The rheology of the IL/block copolymer solutions was investigated, evaluating the storage and loss moduli. Most membranes prepared with ionic liquid had higher water flux than pure block copolymer membranes without additives.

Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. By these methods porous supports could be easily coated with semi-crystalline cellulose. The membranes were hydrophilic with contact angles as low as 22.0°, molecular weight cut-off as low as 3000 g mol−1 with corresponding water permeance of 13.8 L m−2 h−1 bar−1. Self-standing cellulose membranes were also manufactured without porous substrate, using only ionic liquid as green solvent. This membrane was insoluble in water, tetrahydrofuran, hexane, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and N,N-dimethylacetamide.

A simple and efficient approach towards the fabrication of a skinned membrane with highly ordered pores in the nanometer range is presented here. We successfully combined the self-assembly of PS-b-PEO block copolymer and water induced phase separation for the preparation of isoporous PS-b-PEO block copolymer membranes. We produced for the first time asymmetric isoporous PS-b-PEO membranes with a 100 nm thin isoporous separating layer using water at room temperature as coagulant. This was possible by careful selection of the block lengths and the solvent system. FESEM, AFM and TEM measurements were employed to characterize the nanopores of membranes. The pure water fluxes were measured and the flux of membrane was exceptionally high (around 800 L m−2 h−1 bar−1). Protein rejection measurements were carried out for this membrane and the membrane had a retention of about 67% of BSA and 99% of γ-globulin.

Mixed matrix materials made from selective inorganic fillers and polymers are very attractive for the manufacturing of gas separation membranes. But only few of these materials could be manufactured into high-performance asymmetric or composite membranes. We report here the first mixed matrix composite membrane made of commercially available poly (amide-b-ethylene oxide) (Pebax®1657, Arkema) mixed with the nano-sized zeolitic imidazole framework ZIF-7. This hybrid material has been successfully deposited as a thin layer (less than 1 μm) on a porous polyacrylonitrile (PAN) support. An intermediate gutter layer of PTMSP was applied to serve as a flat and smooth surface for coating to avoid polymer penetration into the porous support. Key features of this work are the preparation and use of ultra-small ZIF-7 nano-particles (around 30–35 nm) and the membrane processability of Pebax®1657. SEM pictures show that excellent adhesion and almost ideal morphology between the two phases has been obtained simply by mixing the as-synthesized ZIF-7 suspension into the Pebax®1657 dope, and no voids or clusters can be observed. The performance of the composite membrane is characterized by single gas permeation measurement of CO2, N2 and CH4. Both, permeability (PCO2 up to 145 barrer) and gas selectivity (CO2/N2 up to 97 and CO2/CH4 up to 30) can be increased at low ZIF- loading. The CO2/CH4 selectivity can be further increased to 44 with the filler loading of 34 wt%, but the permeability is reduced compared to the pure Pebax®1657 membrane. Polymer chain rigidification at high filler loading is supposed to be a reason for the reduced permeability. The composite membranes prepared in this work show better performance in terms of permeance and selectivity when compared with asymmetric mixed matrix membranes described in the recent literature. Overall, the ZIF 7/Pebax mixed matrix membranes show a high performance for CO2 separation from methane and other gas streams. They are easy to fabricate, which makes them attractive for industrial scale gas separation.

In this work carbon dioxide selective membrane materials from a commercially available poly(amide-b-ethylene oxide) (Pebax ® , Arkema) blended with polyethylene glycol ethers are presented. The preferred PEG-ether was PEG-dimethylether (PEG-DME). PEG-DME is well known as a physical solvent for acid gas absorption. It is used under the trade name Genosorb ® in the Selexol ® process (UOP) for acid gas removal from natural gas and synthesis gas. The combination of the liquid absorbent with the multiblock copolymer resulted in mechanically stable films with superior CO 2 separation properties. The addition of 50 wt.% PEG-DME to the copolymer resulted in a 8-fold increase of the carbon dioxide permeability; the CO 2 /H 2 -selectivity increased simultaneously from 9.1 to 14.9. It is shown that diffusivity as well as solubility of carbon dioxide is strongly increased by the blending of the copolymer with PEG-ethers.

Polyethylene glycol improved the gas permeability and selectivity of Pebax ® (poly(amide-b-ethylene oxide) copolymer) membrane. To understand this, the free volume variation in these blend membranes was studied from T = −80 to T = 100 °C by positron annihilation lifetime spectroscopy (PALS). A small difference in o-positronium lifetime between pristine polymer and blend with 50 wt.% of polyethylene glycol was observed between −10 and 10 °C. However, at room temperature no significant changes of free volume are detected due to the apparent molten state of polyethylene oxide. The gas permeability measurements, PALS analysis, fractional free volume (FFV) obtained from density and the theoretical correlation between diffusion coefficient and FFV show a good agreement. Thus, we could conclude that the performance of rubbery-like block copolymer membranes can also be improved by controlling the total free volume (addition of an appropriate plasticizer), and not only by solubility selectivity increase as commonly reported.

In the present work, membranes from commercially available Pebax® MH 1657 and its blends with low molecular weight poly(ethylene glycol) PEG were prepared by using a simple binary solvent (ethanol/water). Dense film membranes show excellent compatibility with PEG system up to 50 wt.% of content. Gas transport properties have been determined for four gases (H2, N2, CH4, CO2) and the obtained permeabilities were correlated with polymer properties and morphology of the membranes. The permeability of CO2 in Pebax®/PEG membrane (50 wt.% of PEG) was increased two fold regarding to the pristine Pebax®. Although CO2/N2 and CO2/CH4 selectivity remained constant, an enhancement of CO2/H2 selectivity (∼11) was observed. These results were attributed to the presence of EO units which increases CO2 permeability, and to a probable increase of fractional free-volume. Furthermore, for free-volume discussion and permeability of gases, additive and Maxwell models were used.

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 ,N 2 ,C O 2 ,C H 4, 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.