Surface-Engineered Polyethersulfone Membranes Using Thermo-Responsive Poly(N-Isopropyl Acrylamide) with Antibiofouling Properties for Water Treatment Applications

In this study, we employed a chemical redox initiator system to graft poly(N-isopropyl acrylamide) (PNIPAM) onto the polyethersulfone (PES) membrane’s surface up to a grafting yield of ~ 25%, not reported elsewhere. This modification significantly improved the fouling resistance of the PES membrane. Additionally, the study evaluated the effects of different degrees of PNIPAM grafting yield (5%, 15%, and 25%) on the performance of the membrane. The results demonstrated that the grafted membranes exhibited increased hydrophilicity and responded dynamically to changes in feed temperature, confirming their thermo-responsive nature. The receding contact angle for the membrane with 25% PNIPAM grafting yield was significantly low (~ 10°) at a temperature below 33 °C but increased to 37° when the temperature surpassed 40 °C, demonstrating the temperature-dependent changes in surface wettability of the PES membranes grafted with PNIPAM. The membranes with 15% and 25% grafting yield demonstrated superior resistance to fouling by BSA protein, with higher cleaning efficiency and flux recovery rates exceeding 97%. Furthermore, the PNIPAM-grafted PES membranes showed excellent oil rejection rates exceeding 98%. These findings demonstrate that PNIPAM-grafted PES membranes have promising potential for water treatment purposes and highlight the effectiveness of polymer grafting as a membrane modification method.