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[Display omitted] • Antifouling property of the membrane was improved by UV-initiated grafting. • Surface charge was regulated by electrostatic adsorption. • The membrane showed excellent antifouling properties when filtrating various foulant solutions. • The membrane was very stable due to the covalent bonding. In this study, positively charged monomers were grafted onto negatively charged membranes via UV radiation to improve the antifouling/antibiofouling properties of the polymeric membrane and the stability of the modification layer. The surface properties, morphologies, antifouling and antibiofouling properties, and stability of the modified membranes were systematically characterized. Results indicated that the introduction of [2-(methacryloyloxy) ethyl] trimethylammonium chloride (MTAC) monomers onto polyethersulfone (PES)/sulfonated polyethersulfone (SPES) membranes effectively increased the surface hydrophilicity. Meanwhile, the surfaces were neutralized with ~0 mV zeta potential in pH 3–10. Moreover, the formation of a polyampholytic copolymer and the antibacterial ability of MTAC considerably improved the antibiofouling properties of the modified membranes. The MTAC-grafted PES/SPES membranes showed excellent antifouling/antibiofouling properties during the treatment of various types of wastewater, including bovine serum albumin solution, oil/water emulsion, and bacterial suspension. Therefore, this study provides a simple and effective method of constructing stable and antifouling membranes for sustainable water treatment. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel positively charged nanofiltration membrane was prepared. • Dense separation layer was formed via simultaneous cross-linking/quaternization. • Resultant membrane showed high the mono-/divalent ion selectivity. Abstract A novel positively charged nanofiltration membrane was designed and prepared by a simultaneous cross-linking/quaternization of poly(m -phenylene isophthalamide)/polyethyleneimine (PMIA/PEI) blend precursor membrane. To improve the PEI retention ratio during precursor membrane fabrication, propanetriol glycidyl ether (PTGE) was used as a cross-linker. For nanofiltration preparation, the cross-linking time and p -xylylene dichloride (XDC) concentration were optimized. A comprehensive characterization of the nanofiltration membrane was conducted in terms of chemical composition, surface morphology, surface charge, pore structures and separation properties. Results indicated that the density of the positive charge increased after the simultaneous cross-linking/quaternization. The nanofiltration membrane with pore size in the range of 0.5–2 nm exhibited high MgCl 2 rejection of 94.4% and water permeability of 37.3 L m−2 h−1 at 0.4 MPa. Furthermore, to make a comparison between the PMIA/PEI nanofiltration membrane and the other PEI based nanofiltration membranes in the previous studies, an empirical upper bound correlation between water permeability and water/salt selectivity was established. Due to the high density of positive charge on the membrane, the mono-/divalent ion (Na+/Mg2+) selectivity of this novel nanofiltration membrane was at a high level compared with recent reports and much higher than commercial nanofiltration membranes. This work provides an effective method for fabricating the highly positively charged nanofiltration membrane which has great potential for multivalent cations separation. [ABSTRACT FROM AUTHOR]

Abstract Different from the typical interfacial polymerization for nanofiltration membrane fabrication, we proposed a novel method to prepare charged nanofiltration membrane via rapid immersion thermal annealing process with the ultrafiltration membrane, which was prepared from the amphiphilic copolymer, poly(vinyl chloride) -g- poly(2-(dimethylamino)ethyl methacrylate) (PVC -g- PDMA) via non-solvent induced phase separation. The pore structures and chemical properties of the membranes, and annealing conditions including the media where the membrane was annealed, annealing temperature and time, were investigated in detail. It is found that the porous separation layer was collapsed to be a stable, defect-free, and smooth film as the dense separation layer of nanofiltration membrane when it was annealed in n -heptane above its glass transition temperature (T g) for only 1 min while the pore size cutoff was tailored from 20 nm to 2 nm. Salt rejections were in the order of MgCl 2 > NaCl > MgSO 4 > Na 2 SO 4 at neutral condition due to Donnan repulsion, indicating a typical positively charged nanofiltration membrane. Overall, this rapid immersion thermal annealing process provides a facile and effective strategy to tailor ultrafiltration membrane toward nanofiltration applications for amphiphilic copolymer based membranes. Graphical abstract fx1 Highlights • NF membrane was formed rapidly via thermal annealing from ultrafiltration membrane. • Pore size of NF membrane could be tailored by the annealing condition. • The positively charged NF membranes showed high divalent cations rejection and water permeace. • Outstanding adhesive strength between the supports and the separation layer was attained. [ABSTRACT FROM AUTHOR]

Abstract A polyvinyl chloride (PVC)-based positively-charged nanofiltration membrane was fabricated from polyvinyl chloride- graft -poly(N,N -dimethylaminoethyl methacrylate) by heating and crosslinking treatment. We characterized the surface chemical compositions, membranes structures, surface hydrophilicity and surface charges of the prepared membrane. The estimated membrane pore diameter is 1.98 nm and the pore diameters are in the range of 0.5–2.0 nm. The membrane exhibits excellent water permeability (9.3 L m−2 h−1 bar−1) and salt rejection (93.1% with MgCl 2 solution). Both the heating treatment and crosslinking reaction can diminish the pore size of the precursor membrane. The membrane hydrophilicity is improved after quaternization, leading to higher water permeability compared with the membrane treated by heating only. Moreover, surface quaternization and crosslinking offer the membrane excellent pressure resistance and long-term stability. The prepared nanofiltration membrane has great promise in many applications including water softening and multivalent ion removal. Highlights • Positively charged nanofiltration membrane was directly fabricated from polyvinyl chloride copolymer. • The membrane was formed after the heating treatment and crosslinking reaction. • The membrane exhibited 9.3 L m−2 h−1 bar−1 of water permeability and 93.1% of MgCl 2 rejection. • The membrane had excellent pressure resistance and long-term stability. [ABSTRACT FROM AUTHOR]

In this study, a simple approach was proposed to incorporate zwitterionic copolymers into polymer membranes via electrostatic adsorption to reduce organic fouling and biofouling. Zwitterionic copolymers carrying positive charges were successfully synthesized from [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (MTAC) via radical polymerization. Quartz crystal microbalance (QCM) measurements were conducted to identify the optimum copolymer with suitable monomer ratio for surface coating. The copolymer with an SBMA to MTAC ratio of 7:3, and 1000 ppm polymer concentration showed the highest adsorption. A negatively charged membrane was modified with this zwitterionic copolymer by the dip-coating method, which was finished in 1 min. The surface properties and antifouling properties (i.e. anti-organic fouling and anti-biofouling) of the membranes were characterized. Moreover, the modified membrane was stable in various chemical solutions. Results indicated that improved anti-organic fouling and anti-biofouling properties was attributed to improved hydrophilicity and reduced negative charge. The zwitterionic coating layer was stable after treatment with various solutions (e.g., 70% ethanol, 0.01 M sodium dodecyl sulfate (SDS), 0.1 M sodium chloride (NaCl), and a pH11 aqueous solution) for 6 h. This study provides a simple, stable method of modifying negatively charged membrane to improve antifouling properties, which is of great importance in biomedicine. [ABSTRACT FROM AUTHOR]

Effect of the supporting layer structures on antifouling properties of forward osmosis (FO) membranes in active-layer-facing-draw-solution (AL-DS) mode was investigated through a series of polyketone (PK) membranes prepared by controlling the concentration of the polymer casting solution, initial casting height, and solvent system. A double-skinned FO membrane was prepared by interfacial polymerization on the bottom surface of the PK membrane. The surface pore sizes, bulk porosities, water permeability and alginic acid sodium salt rejection properties of the prepared PK membranes were determined, and the surface roughness, membrane thickness, pure water permeability, salt permeability and FO performance of the PK-based FO membranes were characterized. The alginic acid sodium salt was used to evaluate the antifouling properties of the FO membranes in AL-DS mode. The effect of surface roughness (or surface pore size), membrane thickness, and structural parameter (S value) on the membrane fouling was investigated. The results indicate that decreasing both the surface pore size of the supporting layer and the membrane thickness effectively improves the membrane performance; that is, the membrane possesses both enhanced antifouling properties and water permeability. This work provides firm guidelines for the design of proper supporting layer structures for FO membranes with high performance in AL-DS (or pressure retarded osmosis, PRO) mode. [ABSTRACT FROM AUTHOR]

Novel antifouling and chlorine-resistant ultrafiltration membranes were successfully fabricated using poly(vinyl chloride-co-acrylonitrile-co-sodium 4-styrenesulfonate) (PVC-PAN-PSS), a novel poly(vinyl chloride)-based copolymer, via a non-solvent induced phase separation (NIPS) method. Quartz crystal microbalance data revealed reduced levels of bovine serum albumin (BSA) adsorption on PVC-PAN-PSS films when compared to those of pure poly(vinyl chloride) and polyacrylonitrile films. The morphologies, chemical compositions, surface roughness and hydrophilicity of the membrane surfaces were characterized by field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle goniometer, respectively. The hydrophilicity and antifouling properties of the membranes were clearly shown to increase with increasing level of poly(sodium 4-styrene-sulfonate) (PSS) in the copolymer; the membrane with 2 wt% PSS exhibited the best antifouling properties, namely ~99% of flux recovery ratio for humic acid (1.0 g L −1 ). Furthermore, the pore structures and antifouling properties of the PVC-PAN-PSS ultrafiltration membranes were maintained after soaking in 1000 ppm sodium hypochlorite for 168 h, while common membrane additives such as methacryloyloxyethylphosphorylcholine-co-poly(propylene glycol) methacrylate and Pluronic ® F-127 were rapidly degraded in this oxidizing environment. PVC-PAN-PSS is expected to be a promising ultrafiltration membrane material with both superior antifouling properties and excellent chlorine resistance. [ABSTRACT FROM AUTHOR]

Polyamide 6 hollow fiber membranes were successfully fabricated via a thermally induced phase separation (TIPS) method for the first time to the best of our knowledge. Dimethyl sulfone (DMSO 2 ) and sulfolane were used as diluents for the TIPS method. Also, poly(ethylene glycol) 200, 300, and 400 and 1,3-butanediol were used as bore solutions to control the pores of the selective layer in the lumen side. Furthermore, propylene glycol was used as a mixing component in quenching bath to generate large pores on the outer surface of the hollow fiber membrane. The effects of polymer concentration, diluent, bore solution, and quenching bath on the morphologies, water permeabilities, and mechanical properties of the polyamide 6 hollow fiber membranes were systematically investigated. The relationship between water permeability, mechanical properties, and spinning conditions was discussed in detail. It was observed that all membranes fabricated under different spinning conditions had interconnected and bicontinuous structures through liquid-liquid phase separation. It was also shown that the novel developed polyamide 6 hollow fiber membranes had suitable water permeabilities and good mechanical properties for the tough separation processes in various industries. [ABSTRACT FROM AUTHOR]

To improve the antifouling properties of polymer membranes, a novel phosphate-based zwitterionic polymer (methacryloyloxyethylphosphorylcholine- co -poly(propylene glycol) methacrylate, i.e., MPC-PPGMA) is introduced into the polyvinyl chloride (PVC) membrane matrix. The solubility of this zwitterionic copolymer in common organic solvents and the compatibility between this copolymer and PVC are studied. A series of PVC blend membranes are prepared via non-solvent induced phase separation based on the good compatibility of the copolymer with PVC. Surface chemical compositions, wettability and porous structures of the membranes are characterized. Fluorescence-labeled proteins static adsorption and organic foulant filtration are conducted to evaluate the fouling resistance of the blend membranes. Antibiofouling properties of the membranes are also confirmed by the immersing method. Doping MPC-PPGMA in the casting solution can significantly improve the surface hydrophilicity and antifouling properties of the PVC blend membranes due to the strong hydration ability of the zwitterionic segments. The blend membranes show excellent and stable resistance to both organic fouling and biofouling. Overall, the novel zwitterionic copolymer MPC-PPGMA is a promising candidate to develop antifouling blend membranes due to its high effectiveness and long-term stability in the membranes. [ABSTRACT FROM AUTHOR]

Two new amphiphilic copolymers poly(methyl methacrylate- graft -poly(ethylene glycol) methacrylate) (PMMA -g- PEG) are synthesized and blended into polyvinyl chloride (PVC) to prepare membranes in different coagulation media (water and ethanol) via the non-solvent induced phase separation method. The prepared membranes are characterized by X-ray photoelectron spectroscopy, proton nuclear magnetic resonance, scanning electron microscopy, atomic force microscopy and water contact angle measurement. Their separation performance and fouling resistance (by protein adsorption and foulant filtration) are also compared. It is found that the membrane hydrophilicity is significantly increased by blending amphiphilic copolymer due to the introduction of hydrophilic poly(ethylene glycol) (PEG) segments of the copolymer. The membranes formed in water have more desirable structures (i.e., smoother surfaces and higher porosity) and better performance (i.e., higher permeability and rejection to bovine serum albumin) compared with those formed in ethanol. The amphiphilic copolymer blended membranes formed in the water coagulation bath exhibit excellent antifouling properties, in particular, showing ~100% fouling reversibility. Therefore, blending amphiphilic copolymers and selecting water as the coagulation media can be effective strategies to develop high performance antifouling membranes. [ABSTRACT FROM AUTHOR]

To functionalize poly(vinyl chloride) (PVC) for various applications, monomers containing tertiary amine group are incorporated into PVC via atom transfer radical polymerization (ATRP) initiated by the labile chlorines in their backbones. The kinetics of synthesis was carefully investigated, and it is proven that the grafting polymerization process can be effectively controlled by regulating the reaction time. The membranes are fabricated using PVC and copolymers by non-solvent induced phase separation (NIPS) process. The hydrophilicity and pore structure of copolymer membranes were enhanced as well, these membranes are endowed with positive charge. When PDMA% ( i.e., the PDMA weight percentage in copolymer) is 31.1%, the flux and Victoria blue B rejection are 26.0 L·m·h (0.5 MPa) and 91.2%, respectively. Thus, the newly synthesized polymer is proven to be a promising material for dye separation with positive charges. [ABSTRACT FROM AUTHOR]

Abstract: In this work, polyether chains such as polyethylene glycol (PEG) chains were grafted onto polypropylene (PP) separators based on mussel-inspired dopamine coating. This method was proved to be also effective to modify other separators, such as polyethylene (PE) and polyvinylidene fluoride (PVDF) separators. Meanwhile, considering the extensive utilization of polyether chains in other fields, e.g., water treatment, biomedical, and so on, this work provided a facile and effective way for introducing polyether chains onto the surfaces of the other kinds of materials. Compared to the virgin PP separators, the introduction of polyether chains onto PP separators enhanced the affinity between the separator and liquid electrolyte. The PEG modified PP separators show higher ambient ionic conductivity, up to 0.99×10−3 Scm−1. Also, the PEG chains effectively decreased the interface resistance and enhanced the interfacial stability, which was beneficial for high performances of separators for lithium ion batteries (LIBs). [Copyright &y& Elsevier]

Abstract: In this work, PMMA layer was immobilized onto PE separator skeleton via surface-initiated ATRP based on dopamine pretreatment. The incorporated “active” layer made separator matrix could be swollen by electrolyte solution to some extent and show some properties of gel polymer electrolyte. Resulted separators were characterized by ATR-FTIR, SEM, contact angle and electrochemical methods. The prepared separators showed improved thermal stability. The electrolyte uptake and ionic conductivity were also elevated due to the improved affinity between separator and liquid electrolyte. The room temperature ion conductivity reached up to 1.19×10−3 Scm−1. The stability of liquid electrolyte trapped in the separator was enhanced obviously. Cells assembled with such “active separators” showed better cycle performances. These results primarily showed that it was a promising way to prepare high performance PE based separators for lithium ion batteries. [Copyright &y& Elsevier]

Abstract: Porous high density polyethylene (HDPE) membrane is an important type of separator for lithium ion batteries (LIBs). To improve the electrochemical performances of HDPE-based separators, a copolymer of poly(ethylene-block-ethylene glycol) (PE-b-PEG) was blended into porous HDPE separators via TIPS process. By measuring the composition, morphology and crystallinity, etc., the phase behavior and surface enrichment behavior of the HDPE/PE-b-PEG/LP system were studied. Compared with pure HDPE separators, surface enrichment of PE-b-PEG chains enhanced the compatibility between separators and liquid electrolyte and electrodes. The ionic conductivity of liquid electrolyte soaked blend separator was up to 1.24×10−3 Scm−1 at 25°C. Furthermore, the interface resistance between separator and electrode was effectively reduced by the surface enriched polyether chains. All the results indicated that PE-b-PEG could be a promising blend substance to improve the electrochemical performances of HDPE separators prepared via TIPS process. [Copyright &y& Elsevier]

Polyampholytes, particularly zwitterionic polymers, are commonly used for the surface modification of membranes. This helps to improve the antifouling properties, anti-adhesion properties, and biocompatibility of the membranes. Surface coating and grafting are common surface modification methods; however, these methods lead to pore blocking and stability problems because polyampholytes exist only on the membrane surface. We propose a strategy to fabricate membranes with well-dispersed polyampholytic copolymers via a composite coagulation process. Negatively charged membranes are fabricated in a coagulation bath containing a polyampholytic copolymer. Thus, both membrane preparation and modification via electrostatic adsorption can be achieved via a one-step process. Moreover, the polyampholytic copolymer is expected to be dispersed within the membrane matrix as well as on the membrane surface. The chemical compositions within the membrane were analyzed using X-ray photoelectron spectroscopy combined with argon beam etching technique. The results indicated that the polyampholytic copolymer was well dispersed within the membrane matrix fabricated via this composite coagulation process, whereas only a thin coating layer was formed on the membrane surface via the normal surface coating method. The newly fabricated membrane exhibited greater water flux, better antifouling properties, and higher stability than pristine and surface-coated membranes. This paper presents a method to prepare high-performance membranes with polyampholytic copolymers. Image 1 • Hydrophilic membrane with well-dispersed polyampholytic copolymer was successfully fabricated. • The membrane was prepared via an in-situ composite coagulation process. • Well-dispersed chemical compositions were confirmed by XPS combined with argon beam etching technique. • Composite coagulation process provides a novel strategy for antifouling and high-permeability membrane. [ABSTRACT FROM AUTHOR]

In this study, a stable zwitterionic layer on the surface of a membrane was developed to improve antifouling properties of the membrane, whereby negatively-charged membranes were modified by a positively-charged zwitterionic copolymer via surface adsorption and a cross-linking reaction. Here, 2-methacryloyloxyethyl phosphorylcholine and 2-aminoethyl methacrylate hydrochloride copolymer (P(MPC- co -AEMA)) was used as a model zwitterionic copolymer that can be adsorbed onto negatively-charged surfaces, and cross-linked by glutaraldehyde. The surface chemical compositions, morphology, hydrophilicity, charge, and antifouling properties of the membranes were characterized. Furthermore, the stability of the coating layer was evaluated. The results indicated that the surface hydrophilicity and antifouling properties of the membrane were clearly improved after surface modification. In addition, the stability of the coating layer was significantly increased after cross-linking compared to that after only surface adsorption. This is likely due to the cross-linking of the interpenetrating polymer networks inside the porous structure on the surface. Our findings provide a simple and effective method for surface modification via surface adsorption for use in practical applications. • P(MPC- co -AEMA) was immobilized on surface via adsorption and cross-linking. • The membrane showed improved the antifouling property. • The stability of P(MPC-co-AEMA) was increased after cross-linking. [ABSTRACT FROM AUTHOR]

A metal-organic composite membrane with sub-2 nm pores was developed via interfacial coordination reaction in biphasic systems for the first time. Herein, tannic acid (TA) was dissolved in water, as aqueous phase; iron(III) acetylacetonate (Fe(acac) 3), used as Fe(III) source, was dissolved in n -hexane as organic phase. A detailed study was conducted to obtain the defect-free TA-Fe(III) separation layer, including the salt concentration in aqueous solution, pH of the aqueous solution and the ratio of TA to Fe(acac) 3. The results indicated that the defect-free TA-Fe(III) composite membrane formed when the tris-complex (TA 3 -Fe(III)) was achieved. The optimal condition for preparing TA-Fe(III) composite membrane was using aqueous solution containing 0.4 M NaCl at pH = 6 with the ratio of TA to Fe(acac) 3 of 10. Different from the typical separation layer formed on the membrane surface by interfacial polymerization, the TA-Fe(III) separation layer was formed in the pores of the substrate, which is attributed to the higher diffusion coefficient of Fe(acac) 3 from organic phase to aqueous phase. This work provided a novel strategy to fabricate metal-organic composite membrane with sub-2 nm pores; meanwhile, the new-prepared membrane shows a high Na 2 SO 4 rejection of 97.3% with the water permeance of 8.6 L m−2 h−1 bar−1, and a high VB 12 rejection of 97.6%, indicating an excellent ion/molecule separation performance. Image 1 • TA-Fe(III) composite membrane with sub-2 nm pores was fabricated via interfacial coordination reaction for the first time. • Defect-free TA-Fe(III) composite membrane formed when the tris-complex (TA 3 -Fe(III)) was achieved. • Separation layer is formed in the pores of the substrate. • The membrane exhibited 8.6 L m−2 h−1 bar−1 of water permeance and 97.3% of Na 2 SO 4 rejection. [ABSTRACT FROM AUTHOR]

• Positively charged tight ultrafiltration (PCTUF) membrane was fabricated facilely with amphiphilic polymer. • The PCTUF membranes possessed a positively charged surface and 3.27 nm charged channel. • Trace heavy metal cations could be removed efficiently by PCTUF membrane. • Outstanding perm-selectivity of the PCTUF membrane could outperform the ever-reported membranes. The development of highly efficient membranes technology using low-pressure driven filtration process, is one of the principal challenges in the wastewater treatment field, especially those aimed at the removal of trace heavy metals. In this work, a novel positively charged tight ultrafiltration (PCTUF) membrane was developed to remove heavy metal cations (Mn2+, Co2+, Ni2+, Zn2+ and Cd2+) from contaminated waters via electrostatic repulsion mechanism. The PCTUF membrane was fabricated from a new polymer with poly (vinyl chloride co dimethylaminoethyl methacrylate), P (VC- co -DMA) via a nonsolvent induce phase separation (NIPS) process and following facile surface quaternization. The quaternization conditions, the pore structures and chemical properties of the membranes were investigated in detail. The optimally quaternized membrane possessed a positively charged surface and 3.27 nm charged channel with the water permeability of 84 L m−2 h−1 bar−1. The rejections of heavy metal cations surpassed 95% for feed solutions containing 10 ppm heavy metal. Moreover, the influences of feed concentrations and the operating condition with pressure and pH on the membrane performances were also investigated. The results revealed that the prepared PCTUF membrane with its high perm-selectivity performance provides a worthy reference for highly efficient removal of heavy metal cations. [ABSTRACT FROM AUTHOR]

In this work, we present a simple one step blending modification method to fabricate antibacterial PVDF membrane. Effect of membrane surface material properties on the antibacterial activity was investigated. Firstly, a cationic copolymer containing quaternary ammonium cations was synthesized by free radical polymerization of methyl methacrylate (MMA) and dimethylamino-2-ethyl methacrylate (DMAEMA), and following quaternization by iodomethane as an alkylating agent. Via a one-step non-solvent induced phase separation (NIPS) process, blend PVDF membranes were prepared with the copolymers as additive. Only a small amount of copolymer addition (0.9 wt.%) profoundly improved antibacterial activity of the obtained membranes surafce against Escherichia coli ( E. coli ), as a typical model micro-organism foulant, due to enhanced hydrophilicity and incorporation of quaternary ammonium groups on the membrane surface. In particular, the quaternized copolymer using iodomethane imparted the optimized antibacterial performance with both high adhesion resistance (surface occupying, 15%) and high inactivation (cell viability, 0.15%) to E. coli cells. [ABSTRACT FROM AUTHOR]

Positively-charged nanofiltration (NF) membranes have attracted more attention compared with traditional negative NF membranes. In this work, one-step self-assembly strategy was designed to prepare positively-charged NF separation layer by the close packing of poly(styrene- r -quaternized 2-(dimethylamino)ethyl methacrylate) (P(St- r -QDMA)) nanoparticles (NPs) with intramolecular crosslinking structure. Meanwhile, the pore size of NF membrane was tailored by regulating the aggregation of the NPs using different ions and annealing conditions. Herein, water was used as a dispersant to obtain P(St- r -QDMA) NPs dispersion, which is non-toxic and green. The pore size cut-off (PSCO) of the separation layer is well controlled in the range of 0.98–4.04 nm. The optimal membrane showed molecular weight cut-off (MWCO) of 380 Da (i.e., PSCO, 0.98 nm) with the isoelectric point of 9.4, which effectively improved the separation performance for divalent cations (97.2 % for MgCl 2 and 96.0 % for CaCl 2) and neutral small molecules (97.7 % for VB 12 and 92.5 % for PEG400). This work gives a novel and convenient method to construct positively-charged NF membrane with controlled pore sizes, which will be a promising candidate for water softening and molecular separation. [Display omitted] • Positively-charged nanofiltration membrane was prepared by nanoparticles assembly. • The pore size of membrane was tailored by ion concentration and annealing temperature. • It is a novel and convenient preparation method. • The membrane is promising in water softening and molecular separation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel binary organic phosphonic acid was firstly integrated into nanofiltration membrane. • The rejection of membrane incorporated with AA was improved, while the permeability exhibited no decline. • Mono-/divalent anion selective separation factor surpass 500 even in high saline solution up to 20 g/L. • The membrane exhibit excellent chlorine resistance and anti-fouling performance. Nanofiltration membrane (NF) have become increasingly crucial in ion separation. However, traditional polyamide (PA) NF suffers from poor selectivity for mono-/divalent anions due to weak charges and structure defects. Thus, a novel binary organic phosphonic acid, alendronic acid (AA), was firstly used as an aqueous co-monomer via interfacial polymerization (IP) to create negatively charged nanofiltration membranes with both higher charge density and pore size homogeneity for the separation of mono-/divalent anions. Both structure characterization and performance tests demonstrated the successful introduction of AA in the separation layer. Compared with pristine membrane, the NaCl/Na 2 SO 4 selectivity of membrane incorporated with AA was four times improved, while the permeability exhibited no decline. Simultaneously, the separation efficiency of Cl-/SO 4 2- was tested in NaCl/Na 2 SO 4 binary mixed solutions with varying total concentrations and different mass ratios, and the separation factor consistently exceeded 500 across a concentration range of 1 g/L to 20 g/L. Moreover, the AA-integrated membrane exhibited excellent chlorine resistance after 20000 ppm·h of chlorine treatment, which is promising for high efficiency separation of mono-/divalent anions in industrial applications. [ABSTRACT FROM AUTHOR]

To improve the performances of HDPE-based separators, polyether chains were incorporated into HDPE membranes by blending with poly(ethylene- block-ethylene glycol) (PE- b-PEG) via thermally induced phase separation (TIPS) process. By measuring the composition, morphology, crystallinity, ion conductivity, etc, the influence of PE- b-PEG on structures and properties of the blend separator were investigated. It was found that the incorporated PEG chains yielded higher surface energy for HDPE separator and improved affinity to liquid electrolyte. Thus, the stability of liquid electrolyte trapped in separator was increased while the interfacial resistance between separator and electrode was reduced effectively. The ionic conductivity of liquid electrolyte soaked separator could reach 1.28 × 10 S·cm at 25°C, and the electrochemical stability window was up to 4.5 V (versus Li/Li). These results revealed that blending PE- b-PEG into porous HDPE membranes could efficiently improve the performances of PE separators for lithium batteries. [ABSTRACT FROM AUTHOR]

Three well-defined diblock copolymers of poly(methyl methacrylate- b-methacrylic acid) (P(MMA- b-MAA)) were synthesized using atom transfer radical polymerization method and varying poly(methacrylic acid) (PMAA) chain lengths. These copolymers were blended with PVC to fabricate porous membranes via phase inversion process. Membrane morphologies were observed by scanning electron microscopy (SEM), and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy (XPS). Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes. It was found that, the blend membranes containing longer PMAA arm length showed lower static protein adsorption, higher water permeation flux and better protein solution flux recovery. [ABSTRACT FROM AUTHOR]

Antiviral ultrafiltration membranes (UF) were successfully fabricated using amphiphilic polyvinylchloride-co-acrylic acid) (PVC-AA), which were incorporated with organometallic compound manganese acetylacetonate Mn(acac)3. Non-solvent induced phase separation (NIPS) method was used to prepare the UF membrane based on PVC-AA. Fabricated membranes were characterized by different analytical methods. The fabricated membranes (PVC-AA/ Mn(acac)3) provided the highest removal percentage for proteins when compared to the neat amphiphilic (PVC-AA). The hydrophilicity and antifouling properties of the membranes were improved with increasing load of manganese acetylacetonate Mn(acac)3 in the polymeric solution to 1%. The membrane with 1 wt% Mn(acac)3 (UF3) exhibited the best antifouling properties using bovine serum albumin 1 g.L−1and sodium alginate 2 g.L−1 and a real sample of wastewater namely ~ 99% of flux recovery ratio. PVC-AA- Mn(acac)3 provided antifouling and antiviral properties. The viral test using real sewage wastewater indicated that the membranes UF 2 and UF3 removes all viruses of 100%, which indicated negative detection in the treated water. [ABSTRACT FROM AUTHOR]

• A dual-functional ultrafiltration membrane containing quaternary ammonium and zwitterionic polymers was prepared. • The antifouling and antibacterial behavior of the membrane was studied. • The membrane showed the improved organic-/bio fouling resistance. • The membrane showed high-efficiency broad-spectrum antibacterial performance. To overcome the organic-/bio- fouling of the membrane, a dual-functional ultrafiltration membrane containing quaternary ammonium and zwitterionic polymers via quaternization and surface radical polymerization was designed, and its antifouling and antibacterial behavior was studied. In this work, poly(vinylidene fluoride)/poly(methyl methacrylate- co -dimethylamino-2-ethyl methacrylate) (PVDF/P(MMA- co -DMAEMA)) blend membrane was quaternized by p -chloromethyl styrene (p -CMS), and the double bonds were introduced onto the membrane surface, which further participated in the polymerization of zwitterionic monomers on the membrane surface. The results indicated that the resultant membrane exhibited obviously improved hydrophilicity and weak positive charge (isoelectric point, 7.49). The membrane presented higher flux recovery ratio and lower protein adhesion compared with the pure PVDF membrane. Meanwhile, the membrane showed high-efficiency broad-spectrum antibacterial performance, that is, the bacteria killing efficiency of S. aureus and E. coli reached 98.2% and 97.0%, respectively. Moreover, the membrane effectively inhibited bacterial adhesion, which is important for the long-term antibacterial properties of membrane. This antifouling and antibacterial PVDF membrane may have potential in the long-term filtration process, especially when dealing with microbiologically contaminated water. [ABSTRACT FROM AUTHOR]

In lithium-ion batteries (LIBs), separators play a vital role in lithium-ion (Li+) transport, and thus affect rate performance, battery life, and safety. Here, a new kind of multifunctional copolymer poly(acrylonitrile-co-lithium acrylate-co-butyl acrylate) (PAAB-Li) is synthesized through soap-free emulsion polymerization, and is used to form homogeneous-covered separator based on PP matrix by a simple dip-annealing process. Compared to the bare PP separator, the modified separators with PAAB-Li enable higher ionic conductivity, higher lithium ion transference number (increased from 0.360 to 0.525), and lower interface impedance (reduced from 155 Ω to 34 Ω). It has been indicated that PAAB-Li functional layer significantly promotes the fast transport of Li+ and improves the compatibility of the separator/electrolyte-electrode interface. The LiCoO2/graphite cells with the PAAB-Li-assisted separator demonstrate excellent cycle stability and rate performance. In addition, the Li symmetric cells with the modified separator stably cycle over 800 h, indicating the functional layer effectively suppresses the lithium dendrite growth. This facile strategy can be easily applied to LIBs requiring high safety and even be scalable to Li metal batteries. Moreover, the possible mechanism of the PAAB-Li functional layer promoting fast and uniform Li+ transport is discussed in this paper. [ABSTRACT FROM AUTHOR]

To improve the permeability and antifouling properties of polyvinyl chloride (PVC) ultrafiltration (UF) membrane, amphiphilic sulfonated polysulfone (SPSF) was introduced into PVC matrix. Three types of PVC/SPSF blend membranes containing different SPSF with the sulfonation degree (SD) of 20%, 30%, and 50% were fabricated by non-solvent induced phase separation (NIPS) process. The excellent compatibility between PVC and SPSF was confirmed by differential scanning calorimetry (DSC). Surface chemical compositions, morphology, roughness, charge, hydrophilicity, permeability and antifouling properties of the pristine PVC membrane and the PVC/SPSF blend membranes were systematically compared and characterized. Due to the improved hydrophilicity and endowed negative charge, the blend membrane showed high water permeability (i.e. 880 L m−2h−1 bar−1), high bovine serum albumin (BSA) rejection (i.e. 95.7%), and high flux recovery ratio (i.e. 96%), which outperformed ever reported and commercialized PVC membranes. Furthermore, the permeability and rejection properties of PVC/SPSF UF membranes were maintained after soaking in acidic and alkaline solutions for 30 days, indicating their outstanding acid and alkali tolerance. Therefore, SPSF was expected as a potential versatile modifier for fabricating high performance UF membranes. [ABSTRACT FROM AUTHOR]

Nanoscale permeation channels are a key factor for molecules or/and ions separation in membrane field. In this work, molecular deposition strategy is designed to construct high-performance nanochannel separation layer for selective separation of small molecules. Herein, octaammonium polyhedral oligomeric silsesquioxane (8NH 3 Cl-POSS) and tannic acid (TA), two kinds of multifunctional molecules with a size of about 1 nm, were used to prepare robust and perm-selective composite membrane through covalently-bonded layer-by-layer (LbL) self-assembly method. The optimized TA-POSS composite membrane exhibited a narrowed pore size distribution from 0.3 to 1.6 nm with a high water permeance of 21 L m−2 h−1 bar−1. The membrane showed desirable rejection of antibiotics (>90%) and enabled to separate them from NaCl solution. In addition, TA-POSS composite membrane showed outstanding stability due to the high degree of crosslinking between TA and 8NH 3 Cl-POSS and their rigid structures. This work gives a novel and green strategy to construct nanochannel composite membranes, which can efficiently separate molecules and salt. Image 1 • TA-POSS membrane was prepared by covalently-bonded LbL self-assembly method. • The membrane showed a permeance of 21 LMH/Bar with MWCO of 440 Da. • The membrane enabled to efficiently separate the antibiotics and NaCl solution. • The membrane showed good stability performance due to the cross-linked structure. [ABSTRACT FROM AUTHOR]

To enhance hexavalent chromium (Cr(VI)) removal performance under acidic conditions, the nanofiltration (NF) membrane with enhanced negative charge was fabricated via introducing 2, 5-diaminobenzenesulfonic acid (DABSA) into polyamide layer. The control membrane (NF-P) was directly prepared from piperazine and 1, 3, 5-benzenetricarbonyltrichloride. Surface chemical compositions, morphology, surface charge, pore size, permeability and pH-dependent separation performance of the fabricated membranes were characterized. The membranes showed the similar water permeance (∼11.5 L m-2 h−1 bar−1) and Na 2 SO 4 rejections (∼98%) under neutral environments. The DABSA introduced NF membrane (NF-PD) was negatively charged in the pH range of 2.5–11, while the isoelectric point for NF-P was ∼pH 4.0. Cr(VI) removal ability was then evaluated under various concentrations and pH environments. The results indicated that NF-PD showed the better Cr(VI) rejection performance in all tested conditions than NF-P, especially under acidic environments (e.g., pH 4 and pH 5). Moreover, there was a fluctuation of the rejection with the increase of Cr(VI) concentration under acidic environments, which was mainly caused by the formation of Cr 2 O 7 2− species. The harmful Cr(VI) was efficiently removed by the NF membrane with enhanced negative charge under acidic environments, which indicated the wider application range of the NF membrane. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fe3+ aggregation has significant influence on the structure of TA/Fe3+ complex. • Pore structure of the TA/Fe3+ nanofilm was demonstrated via molecular dynamic simulation. • TA/Fe3+ nanofilm broke through the selectivity-permeability trade-off of the nanofilms. Abstract The tailored nanofilms have attracted a rapidly growing interest in various separation processes. Recently, microporous materials have provided a promising way to meet this requirement due to their distinct structures. However, suffering from the uncontrollable heterogeneous nucleation, crystalline materials are difficult to form the ultrathin and defect-free nanofilms. Herein, tannic acid (TA)/Fe3+ complex, which was microporous amorphous material, was fabricated on the ultrafiltration membrane via the layer-by-layer technique. Interestingly, in addition to the pH value mentioned in the literature, the aggregation of Fe3+ in the aqueous solution was also found to have significant influence on chemical composition and physical structure of the complex. Through the strict control on the Fe3+ aggregation, the defect-free TA/Fe3+ nanofilm has an average pore size of 0.7 nm, which was the smallest among the reported TA/Fe3+ nanofilms. More importantly, the pore size of nanofilm was in accordance with our expectation, and the molecular dynamic simulation further confirmed the result. It demonstrated that the tailored pore structure of the nanofilm can be designed on the basis of the molecular structure. Moreover, the nanofilm has an ultrathin thickness of 5 nm. To the best of our knowledge, the nanofilm was the thinnest nanofilm used for liquid separation. Compared with the nanofilms made by various materials, the TA/Fe3+ nanofilm obviously broke through the selectivity-permeability trade-off of the nanofilms, with the ultrathin thickness and the narrow pore size distribution. Additionally, the TA/Fe3+ nanofilm can precisely separate molecules that were close in size. This work provides a facile method to fabricate tailored nanofilms with high performance designed at a molecular level. [ABSTRACT FROM AUTHOR]

Lithium metal is a promising anode candidate for the next-generation higher energy density batteries. In this work, a detailed study is carried out to clearly explore the influence of separator wettability on ionic conduction and interface properties for lithium-metal anode batteries. Firstly, polyphenol and polyamine are facilely assembled on the surface of polyethylene (PE) separator with the assistant of periodate. Wettability and electrolyte uptake of the polyphenol-polyamine treated PE separator improves significantly, which resulted in the increase of ionic conductivity and lithium-ion transference number (from 0.37 to 0.49). Subsequently, galvanostatic measurements and electrochemical impedance spectra (EIS) are performed on Li symmetric cells to investigate the effect of separator wettability on interface properties. It is found that the modified PE separator favors the electrochemical process by providing lower interfacial resistance, better interface compatibility, and more uniform deposition of Li + , which correspondingly mitigate the formation of Li dendrites. Finally, lithium-metal anode cells (LiCoO 2 (LCO)/Li) assembled with different separators are tested, and superior battery performance is displayed in case of the polyphenol-polyamine treated substrate. These results are expected to be instructive for the design of more durable Li electrodes. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) has been regarded as a promising membrane-based separation technology with great potential in many fields. In this work, based on the strong electrostatic interaction between nanoparticles (NPs) prepared by the quaternized P(VC- r -DMAEMA) (Q-PVD) and hydrolyzed polyacrylonitrile (HPAN) substrate membranes, separation nanochannels were successfully constructed on the surface of membranes by a one-step coating method. The types of the substrates and concentrations of NPs were optimized to obtain the proper performance. The surface morphology, chemical compositions, surface wettability, surface charge, and pore size were characterized. The obtained thin-film nanocomposite (TFN) membranes exhibited excellent stability in various common organic solvents, such as n -heptane, acetonitrile, ethanol, etc. Furthermore, composite membranes showed excellent retention for dyes with specific molecular weights, with a molecular weight cut-off (MWCO) of 825 Da. In particular, the rejection rates of Coomassie brilliant blue (BB) and Bengal rose red (RB) were 96.6% and 97.9%, respectively. Given the above characteristics, the composite membranes are expected to be used in the field of OSN. [Display omitted] • The amphiphilic copolymer nanoparticles were assembled to construct nanochannels. • The one-step coating method simplified the preparation procedure of OSN TFC membranes. • The membrane showed excellent separation capacity for dyes with specific molecular weights. • Further development of this technology is expected for tailor-made OSN membranes. [ABSTRACT FROM AUTHOR]

To prepare thin film composite (TFC) nanofiltration (NF) membranes with improved flux and rejection performance at low pressure, hyperbranched polyester (HPE) was selected as the nano-sized macromonomer and successfully incorporated into the skin layers on PVC hollow fiber substrates via interfacial polymerization between trimesoyl chloride and the mixtures of hydroxyl-terminated HPE/piperazine (PIP). The resultant NF membranes were characterized using ATR-FTIR, FESEM, AFM and surface zeta potential, while their performance was evaluated in terms of permeate flux and rejection rates of different inorganic salts and neutral solutes. When the HPE content was lower than 60 wt% in HPE/PIP mixtures, the increased membrane surface roughness and the HPE embedded in skin layer effectively enhanced the permeate flux without sacrificing salt rejection for the prepared TFC NF membranes. Further increasing HPE content in HPE/PIP mixtures yielded looser polyamide skin layer, which led to the decline of solute rejection. Due to the larger size and good interfacial compatibility with cross-linked polyamide matrix, the incorporated HPE could exist stably in the skin layer. And thus, the prepared TFC NF membranes showed good flux and rejection stability in a long-term filtration process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Permeation channel was constructed via amphiphilic copolymer nanoparticles packing. • The copolymer nanoparticles were prepared by soap-free emulsion polymerization. • The membrane showed the high selectivity towards amino acids and biopeptides. • This method simplified preparation of NF membrane via nanoparticles packing route. Nanofiltration (NF) as a promising candidate is widely used in charge-based separation of ampholytic biomolecules. Construction of strongly charged permeation channel of NF membrane is one of the key factors for this process. In this work, random amphiphilic copolymer (RACP) nanoparticles were first packed to prepare nanoscale permeation channel. The RACP emulsion was firstly prepared by soap-free emulsion polymerization between [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride (DMC) and methyl methacrylate (MMA), and then directly depositing onto porous substrate to form nanochannel selective layer of NF membrane. The optimal NF membrane shows a relatively large pore structure (i.e., cut-off pore size is 1.43 nm) and high pure water permeance (PWP) of 13.3 L·m−2·h−1·bar−1. Moreover, it shows a desirable rejection of basic amino acids and biopeptides (i.e., ∼95%) and allows neutral or acidic ones with similar molecule weight to permeate through. This work provides an innovative and facile method directly from RACP emulsion to construct NF membrane via nanoparticle packing, which greatly simplifies the preparation procedure for NF membrane. In addition, this novel NF membrane also demonstrates great potential in charge-based separation of biomolecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • P(MMA-co-DMAEMA) was synthesized and blended with polysulfone UF membrane. • Blend PSF-PMD membrane was quaternized to increase surface positive charge. • Membrane was grafted with 2-carboxyethyl acrylate for surface neutralization. • Neutralization resulted in comprehensive anti-fouling smooth membrane surface. • Surface charge control is simple and effective to mitigate membrane fouling. In this study, a new poly(methyl methacrylate-co-dimethyl aminoethyl methacrylate) (P(MMA-co-DMAEMA))-based membrane was fabricated and modified to control surface charge in order to improve fouling resistance. The positively-charged P(MMA-co-DMAEMA) copolymer was first synthesized from the free radical polymerization of methyl methacrylate (MMA) and dimethylamino-2-ethyl methacrylate (DMAEMA). The copolymer was blended with polysulfone and cast into a membrane via nonsolvent-induced phase separation. The membrane was then quaternized using iodomethane and neutralized by grafting 2-carboxylethyl acrylate via UV irradiation. The membrane surface charge, composition, morphology, hydrophilicity, and anti-fouling properties were evaluated. Surface charge control of the membrane resulted in outstanding antibacterial activity and fouling resistance against model protein foulants. While the incorporation of P(MMA-co-DMAEMA) in the membrane and its quaternization greatly improved the surface hydrophilicity of the membrane and endowed positive surface charge as well. Neutralization of the blend membrane endowed a smooth and electroneutral surface layer on the membrane surface, which led to not only excellent anti-bacterial activity and comprehensive resistance against charged foulants, but also high flux retention after simple membrane washing. Dynamic filtration using protein and bacterial foulants revealed the ability of the membrane with almost zero net surface charge to regulate fouling even in practical filtration applications. The results in this study exhibit a simple and effective method for mitigation of membrane fouling propensity for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • An in-situ crosslinked binder with optimized crosslinked structures was fabricated. • The crosslinked networks achieve high adhesive strength to maintain cathode integrity. • Strong interaction of electron-donating groups to LiPSs suppresses the shuttle effect. • Coordination between N, O atoms and lithium ions facilitates ion transfer. • The Li-S battery with this binder shows outstanding cycling and rate performance. An in-situ crosslinked binder based on a new chlorine-containing anionic copolymer for high-performance lithium-sulfur battery is fabricated. The elaborately constructed and optimized network structure shows excellent adhesion strength and suitable electrolyte swellability that ensuring the electrode integrity during long-term cycling. The abundant electron-donating groups on the polymer networks endow sulfur cathode with high lithium-ion conduction and polysulfide-trapping capacity, promoting the electrochemical kinetics. These effects are proved by cyclic voltammetry tests, UV–Vis absorption spectrum, X-ray photoelectron spectroscopy, and density-functional theory calculation (DFT). Consequently, sulfur cathode with this crosslinked binder exhibits a high initial capacity of 1038.1 mAh g−1 and high capacity retention of 77.4% after 800cycles at 0.5C. After 800cycles at 1.0C, the sulfur cathode holds a discharge capacity of 684.2 mAh g−1 and a capacity decay of only 0.033% per cycle. What's more, the cathode still gains a discharge capacity exceeding 800 mAh g−1 at the rate of 3C. This work gives an effective method to design functional binder for high-performance sulfur cathode with polysulfide-trapping and ion-transporting features. [ABSTRACT FROM AUTHOR]

Nanofiltration (NF) membrane has an extensive application in the field of water treatment, but weakly negative surface-charge and even charge inversion in acidic environment restrict wide applications of traditional aromatic polyamide (PA) thin film composite (TFC) NF membrane in a broad pH range. In this work, 4, 4′-diaminostilbene-2, 2′-disulfonic acid (DSDA), a novel acidic aqueous monomer, was introduced into interfacial polymerization to fabricate a TFC NF membrane with enhanced negative charge and pH stability. The effects of interfacial polymerization parameters were investigated to improve membrane performance. The optimal membrane exhibits a pure water permeance (PWP) of 10.0 ± 0.5 L m−2 h−1·bar−1 and a high Na 2 SO 4 rejection (i.e., ~97.0%). The resultant membrane remains a strongly negative charge when the pH value is changed from 2 to 12. Due to enhanced negative charge, Donnan exclusion plays a significant role in membrane separation process, which results in a huge superiority in removal of Na 2 SO 4 , Na 3 PO 4 and K 2 Cr 2 O 7 in a broad pH range especially in acidic environment. Hence, it is demonstrated that the negative-charged NF membrane prepared in this work has improved and stable separation performance under a broad pH range, which expands application scopes of NF membrane, especially in removing Cr (VI) and phosphate in acidic environments. Besides, this study also provides a feasible route for preparation of suitable TFC NF membrane for working in acidic environment via introducing strongly acidic groups in selective layer. [Display omitted] • The thin film composite nanofiltration membrane with enhanced negative charge was fabricated. • A novel monomer-4, 4′-diaminostilbene-2, 2′-disulfonic acid was used for interfacial polymerization. • The membrane had great superiority in removal of Cr (VI) and phosphate in acidic environment. • This novel membrane expands the application range of nanofiltration in wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cationic poly(amido-amine)s (PAMAMs) were synthesized for a novel PA nanofilm. • Cationic PAMAM incorporated polyamide (PA) nanofilm is Janus charged. • Selectivity of the Janus charged PA nanofilm to mono-/divalent ions is up to 65. • The Janus charged PA nanofilm shows enhanced hard water softening performance. Nanofiltration (NF) membranes with ultra-high separation selectivity to both mono-/divalent anions and cations are desirable for treatment of practical water with complex composition of ions. In this work, a facile and universal method for fabricating polyamide (PA) NF membranes with both ultra-high separation selectivity to mono-/divalent anions and cations was developed. Cationic poly(amido-amine) (PAMAM) dendrimers with different numbers of terminal quaternary ammonium groups were synthesized and incorporated into the polyamide (PA) matrix by interfacial polymerization (IP) to modulate both charge properties and network structures of the PA nanofilms. Contributed by the heterogenous distribution of PAMAM G5-TAC2, a Janus charged PA nanofilm was successfully fabricated. The negatively charged top surface of the PA nanofilm leads to a high electrostatic repulsion to divalent anions while its positively charged back surface exerts a high electrostatic repulsion to divalent cations. Moreover, the network structures of the PA nanofilms are precisely modulated to accelerate the transport of water molecules (103.5 L m−2h−1 MPa−1). Based on the synergistic effect of steric and Donnan effects, the transports of both divalent anions and cations through the G5-TAC2/PIP membrane are hindered, while the transports of monovalent ions are free, so that both ultra-high separation selectivity to mono-/divalent anions and cations (both above 65) can be achieved. Compared to PIP only membrane, G5-TAC2/PIP membrane exhibits high-efficiency in mixed ion separation process. [ABSTRACT FROM AUTHOR]

High-efficient separation of molecules is of great significance in food, biotechnology, pharmaceutical and dairy industries. To this end, cationic hyperbranched poly (amido-amine)s (HBPs) with different numbers of quaternary ammonium groups were employed as a new kind of 3D spherical macromonomers to fabricate nanofiltration (NF) membranes, through interfacial polymerization (IP) between cationic HBPs and trimesoyl chloride (TMC) on a polyvinyl chloride ultrafiltration (PVC-UF) hollow fiber membrane surface. Apart from the inner voids inside cationic HBP molecules for fast transport of water molecules, sizes and charge properties of the outer voids between cationic HBP molecules can be modulated by changing the numbers of quaternary ammonium groups on cationic HBP molecule surfaces for enhancing both high permeability and selectivity (water permeance and MgCl 2 rejection rate of the resultant NF membrane are up to 310.5 L m−2 h−1 MPa−1 and 92.0% respectively). Based on the separation mechanism of combined steric and Donnan effects, the resultant NF membrane exhibits ultrahigh retentions to molecules with high molecular weights (MWs) or positive charges, thus molecular-level selectivity to VB12/VB2 (neutral molecules with distinct MWs) or VB1/VB2 (cationic/neutral molecules with similar MWs) can be achieved. [Display omitted] • Cationic HBPs were synthesized as a novel kind of macromonomers for IP. • Nanochannel in NF membrane selective layers were engineered by cationic HBPs. • HBP-TAC2/TMC membrane exhibits higher water permeability and MgCl 2 rejection. • Separation of molecule mixtures can be achieved based on steric and Donnan effects. [ABSTRACT FROM AUTHOR]

• Polyketone (PK) support membranes were modified with aromatic compounds. • Affinity between PK and aromatic compounds was estimated using Hansen solubility parameters. • PK support membranes modified with m -phenylenediamine (PK-MPD) had a dense structure on the bottom side. • Polyamide (PA)/PK-MPD-70, 90, and 110 membranes possessed the high pressure resistance and water flux. • The performance overcame the trade-off relationship between pressure resistance and structural parameter. In this study, we fabricated porous polyketone (PK) support membranes with high pressure resistance and low structural parameter (S) by surface modification with aromatic compounds for osmotically driven membrane process applications. The effects of surface modification of PK using aromatic compounds on the membrane structure, mechanical properties, and membrane performance were investigated. Based on an estimation of the affinity between PK and aromatic compounds using Hansen solubility parameters and mechanical properties, m -phenylenediamine (MPD) was selected as an appropriate chemical modifier for PK membranes. The PK support membranes modified with MPD (PK-MPD) had a dense structure on the bottom side. The thickness and porosity of the PK membranes were changed by the treatment temperature. As a result, polyamide (PA)/PK-MPD thin film composite membranes showed superior pressure resistance in reverse osmosis. PA/PK-MPD modified at 110 °C possessed the highest pressure resistance of 21 bar, which was 3.5 times higher than that of the PA/untreated PK membrane, while maintaining a high water flux of 19.4 L m−2 h−1 in FO. This performance overcame the trade-off relationships between pressure resistance and FO flux and between pressure resistance and S value. [ABSTRACT FROM AUTHOR]

• Flexible PMIA separator and Li-S cathode were successfully integrated with excellent robustness via a simple NIPS method. • The cells assembled with the integrated electrodes can deal with volume expansion of sulfur, diffusion of polysulfides and dendrite growth of Li simultaneously. • The resultant cell exhibits a capacity of 773.6 mAh g−1 at 1 C and after 600 cycles,the capacity still remains at 565.5 mAh g−1 with the calculated capacity fade of 0.045% per cycle. Lithium−sulfur (Li−S) batteries are of great interest in next-generation flexible electronic devices for their much higher energy density. However, current Li−S batteries are still facing the problem about rational construction of the flexible power sources. Herein, a novel flexible and integrated electrode is fabricated through a non-solvent induced phase separation (NIPS) method with poly(m-phenylene isophthalamide) (PMIA) as the flexible support for Li-S batteries. Notably, the integrated electrode shows the capability of adapting the volume expansion of cathode materials, inhibiting the diffusion of lithium polysulfides and suppressing the dendrite growth of Li. As a result, battery assembled with the fabricated electrode exhibits a capacity of 773.6 mAh g−1 at 1 C. After 600 cycles, the capacity still remains at 565.5 mAh g−1 with the calculated capacity fade of 0.045% per cycle. This proposed strategy is advanced and feasible, which has great potential in next-generation portable electronic devices. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Nanofiltration membranes (NFMs) with negatively-charged nanochannels (NCNs) are of critical significance for enhancing the rejection of divalent anions. Herein, NFMs with NCNs are fabricated through a facile coating-heating route. Sulfonated polysulfone (SPSF) nanoparticles (13–40 nm) dispersed in aqueous phase are used to generate a dense layer on PES ultrafiltration (UF) membranes with different molecular weight cut-off (MWCO). It is found that the differences in the roughness of the substrates have significant contributions to the packing process of the SPSF nanoparticles, which indicate the smooth surface can be the better one. Scanning electron microscopy (SEM) images suggest the successful fabrication of the dense layer about 200 nm on different substrates. The resultant membranes feature selective layers with the nanochannels from 0.7 to 1.2 nm in average and zeta potential measurements indicate the nanochannel layers are negatively charged, causing the salts rejection in the following sequence: Na 2 SO 4 > NaCl > MgSO 4 > MgCl 2. Furthermore, the constructed membranes exhibit an excellent separation performance with the water flux of 7.2 L m−2 h−1 bar−1 and the rejection rate for Na 2 SO 4 of 94%, which demonstrates a novel economic and effective approach towards fabrication of nanofiltration membranes. Image 1 • Negatively-charged nanochannels were successfully fabricated from aqueous sulfonated polysulfone nanoparticles. • A smoother substrate is benefit to the coating of the SPSF nanoparticles for a better performance. • The prepared nanofiltration membranes exhibited enhanced rejection of divalent anions. [ABSTRACT FROM AUTHOR]