Poly(vinylidene fluoride)/polyethersulfone blend membranes: Effects of solvent sort, polyethersulfone and polyvinylpyrrolidone concentration on their properties and morphology

The effects of some membrane preparation conditions on the characteristics and performance of poly(vinylidene fluoride)/polyethersulfone blend membranes were studied. Poly(vinylidene fluoride) (PVDF) and polyethersulfone (PES) were employed as base polymers. Four different solvents including dimethyl sulphoxide (DMSO), dimethyl formamide (DMF), 1-methyl-2-pyrrolidone (NMP) and dimethyl acetamide (DMAc) were used as the solvents. Polyvinylpyrrolidone (PVP) was used as pore-forming additive. The preparation variables in this work were sort of solvents, content proportion of PVDF/PES, and concentration of PVP. The flat-sheet membranes prepared by phase inversion were characterized by using scanning electron microscopy (SEM). Membrane performance was evaluated by shrinkage ratio, pure water flux and retention to bovine serum albumin (BSA). The shrinkage ratio of PVDF/PES blend membrane was much reduced when DMAc was used as a solvent. The pure water flux of blend membranes reaches the maximum and the retention to BSA reaches the minimum when the casting solution contains 1.5 wt% PES and 5 wt% PVP.