Enhanced antifouling PSE hollow fiber membrane via zwitterionic copolymer segregation

Blending hydrophilic additives is an effective method to improve the surface hydrophilcility and antifouling property of ultrafiltration membranes. In this study, we prepared a series of polysulfate (PSE) hollow fiber membranes (HFMs) containing a zwitterion-based copolymer, poly(4-vinylpyridine-co-methylacryloxyethyl phosphocholine), with varying monomer ratios and blending quantities. The relationship between cast solution properties and phase separation behavior was investigated, as well as the impacts of copolymer composition and amount on the separation performances and antifouling abilities of the membranes. A higher hydrophilic monomer ratio and more copolymer addition of zwitterionic copolymer would facilitate surface segregation, increasing the hydrophilicity of membrane surface and generating a dense hydration layer. This layer can resist macromolecule contaminants and promote water molecular transport. Furthermore, a more compacted skin layer improves separation ability. The optimized PSE HFMs had water fluxes around 140 L m⁻² h⁻¹, BSA rejections over 97 %, and flux recovery rates over 92 % during operation. Moreover, the membrane demonstrated ultra-low flux-sacrifice when applied to protein solutions while maintaining a high rejection rate, which indicates the distinctive and strong competitiveness of PSE/P(4VP-co-MPC) HFMs.