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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]

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]

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]

ABSTRACT To improve the antifouling property of poly(vinyl chloride) (PVC) membranes, a series of poly(methacrylic acid) grafted PVC copolymers (PVC -g-PMAA) with different grafting degree were synthesized via one-step atom transfer radical polymerization process utilizing the labile chlorines on PVC backbones followed by one-step hydrolysis reaction. PVC/PVC -g-PMAA blend membranes with different grafting degree and copolymer content were prepared by nonsolvent induced phase separation method. The surface chemical composition, surface charge, membrane structures, wettability, permeability, separation performances and the fouling resistance of blend membranes were carefully investigated. The results indicated that the PMAA chains were segregated towards the surface and the membranes were endowed with negative charge. The hydrophilicity and permeability of the blend membranes were obviously improved. Furthermore, the antifouling ability especially at neutral or alkaline environments was also significantly increased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42745. [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]

• 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]

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]