Fabrication of membranes for the liquid separation

Poly(1-vinylpyrrolidone-co-acrylonitrile) copolymers, P(VP-AN), were synthesized via radical copolymerization and then their blends with polysulfone (PSf) were used for the fabrication of ultrafiltration membranes having hydrophilic properties. PSf formed miscible blend with P(VP-AN) copolymers containing AN from 2 wt.% to 16 wt.%, while other copolymers were not miscible with PSf. The miscible blends underwent phase separation on heating caused by lower critical solution temperature-type (LCST-type) phase behavior. PSf also formed miscible blends with PVP when molecular weight of PVP equal to or lower than 10,000. Ultrafiltration membranes were prepared from blends of PSf and P(VP-AN) via phase inversion process, and then their performance was explored. Membranes prepared from the miscible blends of PSf and P(VP-AN) exhibited better performance in solute rejection and water flux than those prepared from PSf (or PSf/PVP blend). The effects of P(VP-AN) addition to the casting solution on the membrane performance were explored by analyzing membrane morphology and blend miscibility.