•TFC RO membranes are prepared using a bis-founctional monomer and a tetraacyl biphenyl chloride as a cross-linking reagent.•The performance of polyamide film can be adjusted by control of the fraction of the two monomers.•The water flux of 43.7 L/m2h and the salt rejection of 99.7% are achieved for PAI-70.The mixed organic monomers of isophthaloyl dichloride (IPC) and 3,3′,5,5′-biphenyl tetraacyl chloride (BTEC) were used to prepare polyamide thin film composite (PA TFC) membranes for seawater desalination. IPC and BTEC act as a linear monomer and a cross-linking agent, respectively. As a result, the ratio of linear portion to cross-linking portion of polyamide film can be controlled by adjusting the fraction of monomer. It was found that the chemical composition, chain segment relaxation property, and the surface morphology of polyamide films changed significantly with the ratio of IPC to BTEC increasing. The rougher surface is formed while less pendant carboxylic acid groups present at higher IPC concentrations or lower BTEC concentrations. As the fraction of IPC increases, the length of linear segment between two cross linking point is increased, hence the enlarged polyamide network pore is formed. When IPC weight percentage increases from 0% to 70%, the water flux of the TFC membrane increases from 30 to 43.7 L/m2 h and the salt rejection increases from 99.3% to 99.7% at 5.5 MPa, 32800 ppm NaCl, 25±3 °C testing condition. We demonstrated that both water flux and salt rejection of the polyamide membrane can be improved by the control of ratio of IPC to BTEC.

•A template-free assembly method has been developed for the synthesis of AEMs.•A synergistic grafting of alkyl siloxane groups to tertiary amines produces the zwitterionic polymer.•The Si-O-Si cross-linked network inhibits membrane swelling and improve the mechanical property.•The membrane showed excellent alkaline stability and solvent resistance.A self-assembly strategy has been developed for the synthesis of anion-exchange membranes (AEMs) with high alkaline stability. Cardo poly(aryl ether sulfone ketone)s with pendent tertiary amine groups were grafted with alkyl siloxane to form a polymer with cation quaternary ammonium groups. This polymer produced a zwitterionic polymer via partially hydrolysis of the alkyl siloxane in weak basic medium. The flexible and transparent zwitterionic polymer membranes possessing a Si-O-Si cross-linked network were prepared via the sol-gel polycondensation reaction and a self-assembly process. The homogeneous and continuous Si-O-Si cross-linked network inhibited membrane swelling and improved the mechanical properties and thermochemical stability. The membrane showed alkaline stability in 1 M NaOH aqueous solution at 60 °C for 600 h and solvent resistance in polar aprotic solvents (DMAc, NMP, and DMSO) at 60 °C for 30 days.Download high-res image (207KB)Download full-size image

•A diacyl chloride compound(I) with phosphonate group (–PO(OCH3)2) was synthesized.•RO membrane from I shows the water flux of 79 L/m2h and salt rejection of 99.1%.•The contact angle decreases from 83° to 38°with I content increasing from 0% to 50%.•The irreversible fouling degree reaches 6.8% after 1500 min three cycles fouling.A novel diacyl chloride monomer dimethyl (3,5-bis(chlorocarbonyl)phenyl)phosphonate (compound(I)) with a phosphonate group (–PO(OCH3)2) was successfully synthesized and then blended with 2,2′,4,4′-biphenyl tetraacyl chloride (BTEC) as organic phase monomers to prepare RO membranes for brackish water desalination. BM-X was utilized to represent RO membranes prepared by compound (I). X represented the concentration percent of compound (I) (%) in Isopar G solutions，which was the ratio of the concentration of compound (I) to the concentrations of compound (I) and BTEC. When X increased from 0% to 50%, the water flux of BM-X improved from 35 L/m2h to 79 L/m2h while holding high salt rejections (99.1–99.5%). The enhancement of membrane hydrophilicity was certified by the contact angle decreasing from 83° to 38° with compound (I) content increasing from 0% to 50%. Because the improvement of membrane hydrophilicity made for the enhancement of membrane antifouling, BM-50 exhibited a lower water flux decline and irreversible fouling degree compared with a commercial RO membrane (BW30FR, Dow Filmtec). The irreversible fouling degree reached 6.8% after 1500 min three cycles fouling which was lower than 14.1% of BW30FR. Finally, BM-50 showed a very good and stable desalination performance for 30 days measured in a pH=6.0 and 2000 ppm NaCl solution.Download high-res image (166KB)Download full-size image

•Interfacial adhesion between the support and the active layer in TFC was studied.•Impact of support surface pore characteristics on the active layer formation process were investigated.•A mechanism model responsible for delamination of active layer from support was proposed.•Profilometer was proved to be applicable for active layer thickness measurement.Fundamental problems in thin film composite (TFC) reverse osmosis (RO) membranes in terms of the interfacial adhesion between the support and the active layer, the impact of support surface pore characteristics on the active layer formation process and the accordingly obtained active layer properties were investigated. Paper studies mainly includes following aspects: Five types of polysulfone (PSf) supports with varied surface pore characteristic properties were prepared and characterized; Thin film composite (TFC) polyamide (PA) reverse osmosis (RO) membranes were fabricated on these supports via in situ interfacial polymerization (IP) technology under identical IP protocols, and the performance and properties of the obtained TFC membranes were investigated systematically; Three types of these supports produced TFC membranes with both good salt rejection and high water flux. On the other hand, two types of them produced TFC membranes with inferior salt rejection attributed to the delaminated active layer from the support; The root cause for the delamination was explored and a speculated mechanism model for it and for the impact of support surface pore characteristic on the active layer formation was proposed. Furthermore, profilometer was used for the first time to measure the accurate thickness of individual active layer to overcome the shortcomings of the conventional electron microscope technologies. The basic understanding of the interplay between the support and the active layer provides important information for developing of thin film composite (TFC) membranes with improved performance.

•Thermally resistant material PAEK-COOH was synthesized by condensation polymerization reaction.•Novel flat-sheet tight ultrafiltration membrane was prepared by the nonsolvent induced phase inversion method.•PAEK-COOH ultrafiltration membrane has good hydrophilicity and thermal stability, can be applied for removal dyes from wastewater.Cardo poly (arylene ether ketone)s bearing hydrophilic carboxylic acid groups (PAEK-COOH) was successfully synthesized by condensation polymerization of 2-[bis(4-hydroxyphenyl)methyl] benzoic acid and 4,4′-bisfluorodiphenylketone. TGA and DSC analyses demonstrated that the material has an initial decomposition temperature and glass transition temperature of 360 °C and 220 °C respectively, which revealed the excellent thermal stability of PAEK-COOH. Then PAEK-COOH was employed to fabricate tight ultrafiltration membrane by the nonsolvent induced phase inversion process (NIPS). The water contact angle of the prepared membrane is 61.5°, indicating its good hydrophilicity. The PAEK-COOH tight ultrafiltration membrane possesses a pure water flux of 119.6±2.6 L m−2 h−1, dye permeation flux of 100.9±4.3 L m−2 h−1 and rejection of 99.8±0.33% for Congo red at dye concentration of 100 ppm and operation pressure of 0.4 MPa. Membrane has a molecular weight cut off of 9260 Da and gives complete penetration of monovalent inorganic salt NaCl but a slight rejection of divalent inorganic salt Na2SO4 (less than 10%). Thus, the membrane could be used in the decolorization of wastewater or fractionation of dye and salt mixture for dye purification. The membrane also exhibits excellent antifouling performance and anti-dye adsorption properties with a flux recovery ratio of 91.5% for BSA and dye adsorption rate below 5.0% for four kinds of studied dyes, respectively.Download high-res image (343KB)Download full-size image

•In situ crosslinking reaction involved in one-step phase inversion process.•TUF Membrane has thin, dense and integrally skinned separation skin layer.•Membrane has high permeability and rejection for dyes at low operation pressure.•The crosslinked TUF membrane has long term operation stability.Carboxylated cardo poly(arylene ether ketone)s (PAEK-COOH) is a thermally stable and hydrophilic membrane fabrication material. Herein, PAEK-COOH was employed as membrane material, being dissolved in N-methyl-2-pyrrolidone (NMP) and 1,4-dioxane (DO) mixed solvent and activated by adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to prepare polymer casting solution. Then the activated polymer film was immersed into polyethylenimine (PEI) aqueous solution that served as coagulation bath for taking the one-step chemical reaction-involved phase inversion process. As illustrated by the SEM images, the fabricated crosslinked tight ultrafiltration membrane had a dense and integrally skinned separation skin layer. Chemical composition and hydrophilicity of membrane surface were studied by ATR-FTIR and water contact angle, respectively. Those results revealed that, via the in situ crosslinking of activated carboxylic acid group and PEI along with the phase inversion process, the PEI molecules had been covalently bonded onto membrane surface and resulted in the increase of membrane hydrophilicity. The optimized membrane had a molecular weight cut off (MWCO) of 12.7 kDa and an isoelectric point of 7.4, indicating which is slightly positively charged. The one-step chemical reaction involved phase inversion between reactive macromolecules, i.e., activated PAEK-COOH original polymer film and PEI crosslinker in coagulant, was an efficient and convenient approach for fabrication of highly permeable and selective tight ultrafiltration membranes. Membrane had a dye solution permeability of 80–84 L m−2 h−1 bar−1 and Congo red (CR) rejection of 99.9% in 100 h long-term filtration testing, being capable for dye removal from textile wastewater.Download high-res image (240KB)Download full-size image

•The substituent effects on the alkaline stability of the guanidinium cations were investigated.•New GPP-co-PAEK x membranes were synthesized by Ni (0) catalytic coupling copolymerization.•The prepared membranes exhibit good alkaline stability.Four guanidinuium-functionalized model compounds containing different substituent groups were prepared, and the substituent effects on the overall alkaline stability of the guanidinium cations were investigated. Based on the good alkaline stability of the model compounds, novel guanidinium-based anion exchange membranes (AEMs), GPP-co-PAEK x, with controlled microblock structures were subsequently designed and synthesized in good yield via a three step reaction that included a fluorophenyl-amine reaction, methylation and nickel (0)-catalyzed coupling. Notably, the use of a hydrophilic, guanidinium cation-containing component as a raw material in the direct synthesis of AEMs via nickel(0)-catalyzed coupling avoided using hygroscopic Vilsmeier salts and is obviously different from the conventional method that involves bromomethylation or post-quaternization. The GPP-co-PAEK x membranes exhibited lower water uptake values (≤23.4% at 60 °C) and hydroxide conductivities comparable to those of others reported randomly functionalized guanidinium-based AEMs with similar ion exchange capacity (IEC) values. This finding indicates that the GPP-co-PAEK x membranes with controlled microblock structures possess well-developed hydrophilic/hydrophobic nanophase separation, which was confirmed by transmission electron microscopy (TEM). Moreover, long-term alkaline stability tests demonstrated that the alkaline stability of both the hydrophilic guanidiniums groups and the copolymer backbone contributed to the good alkaline stabilities of the GPP-co-PAEK x membranes.Download high-res image (201KB)Download full-size image

•The alkaline stability of pyrrolidinium cationic model compounds was studied.•Novel di-pyrrolidinium and tetra-pyrrolidinium based monomers were synthesized.•Three novel anion exchange membranes (AEMs), including random and block, were prepared.•Block-type AEMs showed better microphase separation and higher conductivity.To design and construct high ionic conductive anion exchange membranes (AEMs), tetra-pyrrolidinium-based block poly(arylene ether sulfone)s were synthesized. Pyrrolidinium groups were densely and controllably introduced into the polymer scaffold using a novel tetra-functionalized monomer, 4, 4′-oxybis (2,6-bis(pyrrolidinyl-1-methyl) phenol) (OBBPYP), which was synthesized via the Mannich reaction. To obtain chemically stable pyrrolidinium cations, the alkaline stabilities of pyrrolidinium-based cationic model compounds with various N-substituted alkyl chains (methyl, ethyl, butyl) were studied using 1H nuclear magnetic resonance (1H NMR) spectroscopy, in which methyl as the N-substituent group exhibited the highest alkaline stability. Based on the results above, a targeted, well-controlled, multiblock structure AEM (QQBPES-2.4OH) with densely concentrated pyrrolidinium cations was obtained via an iodomethane quaternization reaction. The densely concentrated ionic groups provide ionic nanochannels for hydroxide conduction, and the hydrophobic polymer backbone is responsible for the critical membrane mechanical support. As confirmed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS), the QQBPES-2.4OH membrane exhibited a more obvious hydrophilic-hydrophobic microphase structure, compared to the random di-pyrrolidinium cation-based AEM (DQRPES-2.4OH) and tetra-pyrrolidinium cation-based AEM (QQRPES-2.4OH). Moreover, the QQBPES-2.4OH membrane exhibited considerably higher hydroxide conductivity, up to 68.0 mS cm−1 at 80 °C, better flexibility and lower water swelling. The results of this work suggest a novel and scalable approach to the functionalization of polymers for AEMs.Download high-res image (226KB)Download full-size image

•The QPES-X ionomers (F−, I−, PF6−) with different hydrophilicity were prepared by the ion exchange method.•To obtain ultrafiltration membranes with tunable morphology and performance by blending QPES-X with PSF.•The performance of membranes are related to the hydrophilicity of QPES-X ionomers.•The QPES-F/PSF blended membrane demonstrates a water flux of 2163 L m−2 h−1 and BSA rejection of 93%.The original quaternized cardo poly(arylene ether sulfone)s (QPES-I) ionomers was employed as the virgin polyelectrolyte and its counterions (I−) were exchanged with F− and PF6− to prepare QPES with different anions(QPES-X, X = F, PF6), then QPES-X/PSF blended ultrafiltration membranes was prepared by the nonsolvent induced phase inversion process. Scanning electron microscopy (SEM) was used to characterize the cross section morphology and surface morphology of blended membranes, and atom force microscopy (AFM) was employed for obtaining the three-dimensional images of QPES-X/PSF blended membranes, respectively. The surface chemical composition of the asymmetric membrane was investigated by X-ray photoelectron spectroscopy (XPS). Under similar preparation conditions, the water contact angle on membrane surface increased in the order of QPES-F < QPES-I < PSF < QPES-PF6, while the pure water flux of the membranes decreased with that order. The results revealed that the surface and cross section morphology, surface roughness, QPES-X content on membrane surface, as well as the hydrophilicity and performance of blended membranes were closely related to the counterions of QPES-X. Membrane prepared with QPES-F is hydrophilic and possesses outstanding performance among all the investigated materials, demonstrating a water flux of 2163 L m−2 h−1 and BSA rejection of 93% at an 18 wt% polymer concentration and 15% QPES-F content. Antimicrobial activity studies demonstrate that the blended membrane having 15% QPES-F possess a sterilization rate of 73% towards E. coli.Download high-res image (204KB)Download full-size image

•A novel quaternized monomer DTPPM is synthesized via simple chemical synthesis.•A green and low-cost synthetic method for quaternized copolymers is proposed.•The effect of length for hydrophobic chains on AEMs' properties is studied.•The AEM with the longest hydrophobic chain shows the highest alkaline stability.Using cation compounds as raw materials, three quaternized microblock poly(p-phenylene-co-aryl ether ketone)s (s-, m-, and l-QPP-co-PAEK) were synthesized using a nickel (0)-catalyzed coupling reaction. Hydrophilic and hydrophobic moieties were affixed using cationic quaternary ammonium (QA) groups attached to poly(p-phenylene) by a three-carbon interstitial spacer and nonionic dichloride monomers of various lengths, respectively. The morphology, water uptake, swelling ratio, mechanical properties, thermal stability, hydroxide conductivity and alkaline stability of these new membranes were investigated. Experimental results indicated that the membrane with the longest hydrophobic microblock exhibited high hydroxide conductivity (37.6 mS cm−1 at 80 °C) resulting from the aggregation of ionic clusters observed using TEM. The copolymers with longer hydrophobic nonionic segments exhibited improved alkaline stability, suggesting that the hydrophobic chain shields the QA groups and that the polymer chains pack in a manner that restricts rotation. Controlling the distribution of QA groups in poly(p-phenylene) moieties and tuning the block length of nonionic segments are demonstrated to be effective methods for improving the hydroxide conductivity and alkaline stability of anion exchange membranes.Download high-res image (209KB)Download full-size image

Thin film composite nanofiltration membranes were fabricated through dip-coating and in situ cross-linking of quaternized poly(ether ether ketone) containing a certain amount of tertiary amine groups (QAPEEKs) on polyacrylonitrile (PAN) support. The effects of the variables in membrane formation such as the coating polymer concentration, the curing temperature, and the cross-linking agent types on resultant membrane were studied and the membrane properties such as the barrier layer chemical structure, the surface element composition and morphology were investigated. The obtained performance of uncross-linked and cross-linked QAPEEK-70 thin film composites in nanofiltration test was compared. The results indicated that the cross-linking improved the composite membranes’ performance. For instance, the membrane cross-linked by bisphenol A diglycidyl ether (BPADGE) named M-C-BPADGE exhibited a MgCl2 rejection of 97.8%, a water flux of 11.8 L m−2 h−1, a MWCO of 800 Da and corresponding pore size of 0.69 nm, while for its uncross-linked membrane named M-U, a MgCl2 rejection of 91.2%, a water flux of 13.5 L m−2 h−1, a MWCO with 960 Da and a pore size of 0.77 nm were found. Furthermore, the M-C-BPADGE membrane exhibited selectivities of 16.0 for separation of mixed Mg2+ and Na+ cations, much larger than selectivity of 5.2 obtained for M-U, suggesting that the cross-linked membranes are promising in cation separation.The cross-linked membranes showed better salt separation capability and operation stability than uncross-linked membranes.

•Microporous organic polymer networks were used for modifying Nafion membrane.•This strategy improves the interface compatibility between fillers and polymeric matrix.•It also alleviates cavity problem between fillers and polymeric matrix.•Nafion-MOPN-x shows good dimensional stability and low methanol permeability.A series of new Nafion composite membranes have been prepared by the self-assembly of microporous organic polymer networks (MOPNs) and Nafion. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) reveal that MOPNs and Nafion membranes have good miscibility affording homogeneous composite membranes Nafion-MOPN-x. Compared with the recast Nafion membrane, Nafion-MOPN-x composite membranes show excellent thermal and mechanical properties, good dimensional stability, low methanol permeability, and proper proton conductivity. Also, the passive direct methanol fuel cell (DMFC) of Nafion-MOPN-3 membrane presents a maximum power density of 21.5 mW cm−2 at 25 °C. These results show the introduction of MOPNs can improve the interface compatibility and lessen the cavity problem between fillers and polymeric matrix during chemical blend. Therefore, it casts a new light on developing stable polymer electrolyte membranes (PEMs) for fuel cell application.

Polyelectrolyte complex membranes were prepared from poly(acrylic acid-co-acrylonitrile)s and imidazolium-based polycations via a combination of blend film casting and ammonia solution immersion procedures. The membranes were free-standing and tough, showing excellent mechanical properties (with tensile strength of 6.71–23.7 MPa and elongation at break of 15–59%). Hierarchically structured nanopores were formed in the membranes during the ammonia soaking step, due to NH3-triggered –COOH deprotonation and in situ ionic crosslinking with polycations. Zeta potential measurements indicated that the membranes were negatively charged under neutral conditions. The membranes exhibited moderate rejection to salts in the order of Na2SO4 > NaCl > MgCl2, but high rejection to methyl orange (>99.9%).

•A series of novel comb-like amphiphilic copolymers (PES-g-PEO) were synthesized.•The PES-g-PEO copolymers are promising materials to fabricate ultrafiltration membranes.•The PES-g-PEO membranes exhibited remarkable hydrophilic properties and antifouling performances.A series of comb-like amphiphilic copolymers (PES-g-PEO) were synthesized through grafting poly(ethylene oxide) (PEO) to cardo poly(aryl ether sulfone) (PES-NH) backbone. By controlling the ratios of PEO and cardo poly(aryl ether sulfone), amphiphilic copolymers with a range of PEO side chain were obtained and were employed to ultrafiltration (UF) membranes. The PES-g-PEO-XX materials showed high thermal stability (Td > 238 °C) and good mechanical properties especially elongation at break reached to 150% compared to 23% of PES-NH. The contact angle of PES-g-PEO-80 asymmetric membrane was decreased to a slow as 59° which was 30° lower than the value of PES-NH membrane (90°), indicating that PES-g-PEO-80 membrane exhibited remarkable hydrophilic property. No protein adsorption was found on the surface of PES-g-PEO-60 and PES-g-PEO-80 membranes, showing excellent antifouling properties compared to PES-NH. The results of this work suggest that PES-g-PEO copolymers are promising materials for the fabrication of fouling resistant membranes.

Two bis(amine anhydride) monomers containing tetraphenylmethane pendant groups were synthesized from the palladium-catalyzed amination reaction of N-methyl-4-chlorophthalimide with different arylamines, followed by alkaline hydrolysis of the intermediate bis(amine-imide)s and subsequent dehydration of the resulting tetraacids. These monomers were polymerized with the appropriate aromatic diamines to obtain a series of novel poly(amine-imide)s. The obtained polymers exhibited good solubility in many aprotic solvents and had glass transition temperatures in the range of 310 to 395 °C. Thermogravimetric analysis showed that all of the polymers were stable, with 10% weight loss recorded above 510 °C under nitrogen. The surface areas of these novel poly(amine-imide)s ranged from 78 to 290 m2 g−1. Films obtained by casting exhibited a combination of relatively high permeability and modest to good permselectivity with values close to Robeson’s upper bound limit for O2/N2 and CO2/CH4 gas pairs.

•FSPES-x membranes with perfluoroalkyl sulfonic acid groups were synthesized.•The perfluorosulfonated reaction without employing any metal and basic catalysts.•FSPES-3 shows high conductivity, OCV and superior cell performance.A new series of cardo poly(arylene ether sulfone/nitrile)s FSPES-x with perfluoroalkyl sulfonic acid groups have been successfully prepared by the perfluorosulfonic acid lactone ring-opening reaction without using any metal or base catalysts. These materials have been characterized by IR, NMR and TGA. The results indicate that this simple and metal-free method of preparation is highly efficient for controlling both the degree of perfluorosulfonation and the position of the sulfonate group and no side reactions such as crosslinking is observed. The FSPES-x membranes (IEC = 1.17–1.64 m equiv g−1) show the desired characteristics such as good film-forming ability, excellent thermal and mechanical properties, low methanol permeability, high conductivity (up to 0.083 S cm−1 at room temperature), as well as appropriate cell performance compared to Nafion®117. With these properties, such fluorinated sulfonic acid side-chain-type polymers are promising PEM materials for application in fuel cells.

We report a new hydroxyl functionalized microporous organic polymer (MOPOH) based on the polymerization of catechol with terephthalaldehyde using phenolic resin-inspired chemistry. This catechol-decorated material, with surface area of 874 m2 g−1 and micro, mesopores, facilitates the immobilization and dispersion of Pd nanoparticles (NPs) on the polymer matrix. The surface area of the created composite (Pd@MOPOH) decreases to 419 m2 g−1 and the pore size distribution is narrowly distributed at 1.54 nm due to the filling of mesopores. The CO2 capture capacities for MOPOH and Pd@MOPOH at 273 K and 1 bar are 13.4 and 9.2 wt%, respectively. The resultant Pd NPs are crystalline and uniform with a mean diameter of 4.8 nm. The well-dispersed Pd@MOPOH exhibits excellent catalytic activity toward the model reduction of 4-nitrophenol into 4-aminophenol. Significantly, nearly no Pd leaching is detected during the catalytic cycles, showing active and durable nature of the heterogeneous nanocatalyst.

In this study, a cardo poly(aryl ether ketone) ultrafiltration membrane containing an N-chloramine functional group (PEK-N-Cl membrane) was easily obtained via exposure of a cardo poly(aryl ether ketone) ultrafiltration membrane (PEK-NH membrane) to dilute sodium hypochlorite solution. The chlorination process did not harm membrane performance. In addition, the PEK-N-Cl membrane was stable in both air and water. The PEK-N-Cl membrane exhibited excellent antimicrobial properties against both Gram-negative and Gram-positive bacteria (i.e. E. coli and Bacillus subtilis, respectively). The PEK-N-Cl membrane provided 94.2% and 100% reduction of E. coli and Bacillus subtilis, respectively, within 30 min of contact times. Moreover, nearly 100% of the E. coli was killed after 2 h during the filtration process for the PEK-N-Cl membrane. In addition, the water flux decreased by 42% for the PEK-N-Cl membrane compared to 77.6% for the PEK-NH membrane after filtration of the E. coli solution and incubation on LB nutrient agar plate, indicating that the PEK-N-Cl membrane enhibits antifouling. Furthermore, the PEK-N-Cl membrane is recyclable via subsequent exposure to a sodium hypochlorite solution.

•Water-soluble SPES-NH2-70 was used to fabricate thin film composition NF membrane by in situ crosslinking.•The performance of PEGDGE crosslinked nanofiltration membranes was better than GA crosslinked membranes.•PEGDGE crosslinked membrane exhibits a permeate flux of 25.5 ± 3.0 L m−2 h− 1 and Na2SO4 rejection of 96.1 ± 1.1% at 4 bars.•In fouling study, the PEGDGE crosslinked membrane exhibited excellent antifouling ability for humic acid.Thin film composite nanofiltration membranes were fabricated by coating a water-soluble disulfonated poly(arylene ether sulfone) which contained pendant amine groups (SPES-NH2) onto a polysulfone support in conjunction with covalent crosslinking. Two different crosslinkers, glutaric dialdehyde (GA) and poly(ethylene glycol) diglycidyl ether (PEGDGE), were utilized with various concentrations and curing temperatures to optimize the performance of the resulting membranes. Both GA and PEGDGE crosslinked membranes exhibited optimal performance with a 1 wt.% polymer concentration and 90 °C curing temperature. In particular, the optimized PEGDGE crosslinked membranes exhibited a higher permeation flux of 25.5 ± 3.0 L m−2 h− 1 while that of the GA crosslinked membranes was 8.9 ± 3.2 L m−2 h− 1; each membrane exhibited similar levels of Na2SO4 rejection at 96.1 ± 1.1% and 96.6 ± 2.1%, respectively, at 4 bars. The higher flux for the PEGDGE crosslinked membranes was attributed to higher hydrophilicity. Furthermore, the rejection of methyl orange and methyl violet was above 99.9% for both the GA and PEGDGE crosslinked membranes. A fouling study of the PEGDGE crosslinked membrane was carried out using humic acid as a model foulant, and the membranes exhibited excellent antifouling ability, attributed to their high hydrophilicities and strongly anionic characteristics.Download full-size image

Two bis(amine anhydride) monomers containing tetraphenylmethane pendant groups were synthesized from the palladium-catalyzed amination reaction of N-methyl-4-chlorophthalimide with different arylamines, followed by alkaline hydrolysis of the intermediate bis(amine-imide)s and subsequent dehydration of the resulting tetraacids. These monomers were polymerized with the appropriate aromatic diamines to obtain a series of novel poly(amine-imide)s. The obtained polymers exhibited good solubility in many aprotic solvents and had glass transition temperatures in the range of 310 to 395 °C. Thermogravimetric analysis showed that all of the polymers were stable, with 10% weight loss recorded above 510 °C under nitrogen. The surface areas of these novel poly(amine-imide)s ranged from 78 to 290 m2 g−1. Films obtained by casting exhibited a combination of relatively high permeability and modest to good permselectivity with values close to Robeson’s upper bound limit for O2/N2 and CO2/CH4 gas pairs.