The construction of polysulfate membrane with improved ultrafiltration performance via zwitterionic copolymer segregation

Incorporating zwitterionic materials into polymer matrix is an effective method to fabricate high-performance ultrafiltration membranes, which can improve the surface hydrophilicity while optimizing the internal structure of the membrane. In this study, a series of zwitterionic copolymers, 4VP-MPC, were synthesized using 4-vinylpyridine (4VP) and 2-methylacryloxyethyl phosphocholine (MPC), and their impact on the phase inversion process of polysulfate (PSE) was investigated thoroughly by changing the addition amount and altering the copolymer composition. The addition of 4VP-MPC accelerated the phase inversion rate, reduced the skin layer thickness and improved the membrane porosity. Moreover, the hydrophilicity of the membrane surface is enhanced due to the segregation of the zwitterionic copolymer during the membrane formation process. A novel PSE/4VP-MPC membrane with good separation performance and antifouling property was fabricated, with a pure water flux of 221 L/(m2 h bar), a BSA rejection rate of 93.3 %, and a flux recovery rate of 94.6 %. Additionally, when filtering the mixed simulated dialysate, the optimized membrane showed clearance rates of 71.3 % and 97.0 % for lysozyme and urea respectively, while maintaining a high BSA rejection. This PSE/4VP-MPC blend membrane demonstrated potential applications in the field of ultrafiltration, including hemodialysis.