Preparation of amphiphilic block copolymers via RAFT polymerization and preliminary properties exploration of blended membranes with PVDF

Polyvinylidene difluoride (PVDF) membranes have low surface tension and strong hydrophobicity in water treatment process, and are easily polluted by organic substances. Blending modification can effectively improve the hydrophilicity. The surface of modified membranes are easy to form hydrophilic layer to prevent contact between pollutants and membranes, thus improving the anti-pollution properties. Two amphiphilic block copolymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) radical polymerization. The block copolymers and PVDF were mixed by blending method to form hydrophilic modified membranes. The membranes hydrophilicity, surface PAA coverage, and anti-pollution properties increased with increasing ratios of block copolymers/PVDF and PAA in block copolymers. The anti-pollution properties depended more strongly on membranes surface hydrophilicity when block copolymers chemical structures, that was, the PAA ratios, were changed, rather than the ratios change of block copolymers/PVDF. The block copolymers improved crystallization performance of PVDF because of the role of nucleating agent of block copolymers.