The role of pre-evaporation in the preparation process of EVOH ultrafiltration membranes via TIPS

Herein we prepare poly(ethylene-co-vinyl alcohol) (EVOH) ultrafiltration membrane via pre-evaporation combined thermally induced phase separation (TIPS), using a novel co-solvent that is a mixture of sulfolane and 1,3-propanediol. The porous surface is mainly caused by the low cooling rate of pre-evaporation stage. Based on the shorter pre-evaporation time (τ), the evaporation of 1,3-propanediol provides a foundation for asymmetric structure. Subsequently, the quenching effect of water bath forms a dense layer below the porous surface, it is responsible for the rejection of bovine serum albumin (BSA). Finally, when the mass fraction of 1,3-propanediol in co-solvent = 15%, pre-evaporation temperature = 25 °C and τ = 20 s, the resulting EVOH ultrafiltration membrane presents relatively high BSA rejection of 98% and relatively large pure water flux of 302 L m−2 h−1 bar−1.386