Synthesis of amphiphilic functional terpolymers towards preparation of high flux, anti-fouling, micropollutant-capturing ultrafiltration membranes

Traditional method for modification of PVC ultrafiltration membrane depends mainly on blending, but inevitably suffers from additive leakage and poor compatibility between components. Herein, we synthesized amphiphilic functional terpolymers with adjustable chemical structures through in-situ copolymerization of vinyl chloride, acrylonitrile, and dimethyl aminoethyl acrylate, subsequently prepared the terpolymer ultrafiltration membranes by non-solvent induced phase separation. The novel terpolymers endow the membranes with amphiphilic and pH-responsive performances. Compared with the blend membrane, the copolymer had the more stable covalent bonding, and then its hydrophilic segments could anchor and enrich stably to the membrane surface without diffusing into the aqueous phase. As a result, the copolymer membrane not only effectively overcame the disadvantages of blend membrane, but also showed excellent antifouling and permeable properties. Its water flux significantly increases to 469.41 L/(m2·h·bar) from 35.67 L/(m2·h·bar) of pure PVC membrane while the adsorption capacity for bovine serum proteins was reduced. Meanwhile, the copolymer membranes exhibited strong pH-dependent adsorption for anionic dyes and heavy metal ions. The maximum adsorption capacities occurred respectively at pH values of 3.5 and 6.0. In addition, the copolymer membrane can be regenerated by desorbing the adsorbed anionic dyes and heavy metal ions respectively at pH 10 and pH 3.5. This research provides a new strategy for facile preparation of amphiphilic functional ultrafiltration membranes and effective removal of micropollutants.