Improving the hydrophilicity and fouling-resistance of polysulfone ultrafiltration membranes via surface zwitterionicalization mediated by polysulfone-based triblock copolymer additive

• PSF-based triblock copolymer was designed as a blending additive of PSF membranes.
• Membrane surface zwitterionicalization by post-quaternization of PDMAEMA chains.
• Hydrophilicity and fouling resistance of PSF membranes were significantly improved.

Here we report the fabrication and properties of polysulfone (PSF) ultrafiltation (UF) membranes modified by surface zwitterionicalization from a PSF-based block copolymer additive containing poly(N,N-dimethylamino-2-ethylmethacrylate) (PDMAEMA) blocks. Triblock copolymers with PSF as the middle block and PDMAEMA as the end blocks (PDMAEMA-b-PSF-b-PDMAEMA) were synthesized via the combination of condensation polymerization and atom transfer radical polymerization (ATRP). The synthesized amphiphilic copolymer was then blended with PSF resin in solution to prepare UF membranes by traditional phase inversion process. The enriched PDMAEMA chains on membrane surface and pore walls were transformed into zwitterionic poly(carboxybetaine methacrylate) (PCBMA) by the quaternization with 3-bromopropionic acid (3-BPA). Contact angle measurements and filtration experiments showed that the surface hydrophilicity and fouling-resistance of the fabricated membranes were significantly enhanced after block copolymer addition and surface zwitterionicalization. The experimental results of platelet adhesion demonstrated that the hemocompatibility was remarkably improved for the surface-zwitterionicalized membranes, which can find their potential applications in blood filtration and protein separation etc.

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