Surface modification of polypropylene microfiltration membrane by grafting poly(sulfobetaine methacrylate) and poly(ethylene glycol): Oxidative stability and antifouling capability

PolySBMA and polyOEGMA, which are typical polyzwitterion and polyether with good antifouling capability, have been extensively studied in the surface modification of polymer membranes, It is necessary to evaluate their oxidative stability because aqueous solutions with oxidizing agents are usually used to remove foulants from membrane surfaces in practical applications. PolySBMA and polyOEGMA were grafted on PPMM surface via UV-induced graft polymerization. Protein adsorption and filtration results indicate that both of the polySBMA- and polyOEGMA-grafted membranes have excellent hydrophilicity and antifouling capability. However, their oxidative stability against H2O2/Cu2+ and NaClO solutions is remarkably different. FT-IR/AIR and TOF-SIMS analyses show that polySBMA degrades faster than polyOEGMA in the oxidation process, mainly clue to the ester hydrolysis and elimination of sullobetaine units. As a result of 72-h oxidation, the polySBMA-grafted membrane has an increased water contact angle from 36 degrees to 118 degrees and deteriorated antifouling capability, whereas the polyOEGMA-grafted membrane almost maintains the surface properties. Our findings indicate that poly (ethylene glycol)-based graft is a suitable choice in the design of antifouling surfaces for separation membranes. (C) 2015 Elsevier B.V. All rights reserved.