Zwitterionic Modification of PVDF Membranes With PVDF‐ g ‐PSBMA : A Synergistic Strategy for High‐Flux and Antifouling Ultrafiltration

ABSTRACT Polyvinylidene fluoride (PVDF) membranes are widely used in water treatment due to their excellent mechanical properties and chemical stability; however, their strong hydrophobicity often causes membrane fouling. To improve hydrophilicity and antifouling performance, this study synthesized zwitterionic graft copolymer PVDF‐ g ‐PSBMA via atom transfer radical polymerization (ATRP) and blended it with amphiphilic graft copolymer PVDF‐ g ‐PEGMA. Ultrafiltration membranes composed of PVDF‐ g ‐PSBMA/PVDF‐ g ‐PEGMA/PVDF were prepared via non‐solvent induced phase separation (NIPS). Incorporating PVDF‐ g ‐PSBMA significantly enhanced membrane hydrophilicity, reducing the water contact angle from 90° to 61.9°, and optimized surface morphology, increasing surface porosity from 0.25% to 19.36%. Permeation tests showed that adding 1.0 g PVDF‐ g ‐PSBMA yielded a pure water flux of 846.59 L·m −2 ·h −1 with an alginate rejection of ~86.70%. Antifouling evaluation demonstrated flux recovery rates of 83.43%, 88.94%, and 87.69% for lysozyme, sodium alginate, and humic acid, respectively, outperforming pristine PVDF. Resistance analysis indicated that the zwitterionic graft copolymer mitigates fouling by forming a hydrated layer and modulating surface charge. This work provides a novel strategy for developing ultrafiltration membranes with both high flux and robust antifouling capabilities.