Poly(ionic liquid) copolymer blended polyvinyl chloride ultrafiltration membranes with simultaneously improved persistent hydrophilicity and pore uniformity

• Poly(ionic liquid)s copolymer, PMMA-b-PBVImBF 4 , was synthesized. • Blended PVC membrane showed persistent hydrophilicity and enhanced pore uniformity. • 100 % increase of water flux and stable antifouling performance were achieved. Persistent hydrophilicity and uniform pore structure are key features of antifouling ultrafiltration membranes. Here, a poly(ionic liquid) copolymer, poly(methyl methacrylate)-b-poly(1-butyl-3-vinylimidazolium tetrafluoro-borate) (PMMA-b-PBVImBF 4 ), was designed and synthesized by a simple free radical polymerization method and was employed to manipulate the hydrophilicity and pore structure of polyvinyl chloride (PVC) ultrafiltration membranes through the classic non-solvent induced phase separation. The hydrophobic PMMA segment, which has a carbonyl group, could be twined with the PVC chain, thus ensuring that the copolymer was stably anchored in the PVC skeleton, while the hydrophilic PBVImBF 4 segment was segregated on the membrane surface. Membrane hydrophilicity and pore size uniformity were simultaneously enhanced. A 100 % increase in pure water flux, 45.8 % increase in mechanical strength, and 80 % increase in flux recovery rate were achieved when 3.85 wt% PMMA-b-PBVImBF 4 was added. After 3 cycles of BSA filtration, the pure water flux of the copolymer-modified membrane was 267.0 L·m −2 ·h −1 , approximately 4 times that of the pristine PVC membrane. Due to the stable existence of PMMA-b-PBVImBF 4 in the membrane, the improved membrane hydrophilicity was maintained after 30 days of continuous washing.