Hydrophilic modification of poly (vinylidene fluoride) microporous membrane

The graft polymerization of N-vinyl-2-pyrrolidinone onto the poly (vinylidene fluoride) (PVDF)-based microporous membrane containing a small quantity of poly (ether sulfone) (PES) was performed under UV irradiation. The addition of PES in PVDF did not change its mechanical property up to 3.3% in weight, but made the photo grafting on PVDF possible. The results showed that the grafting rate increased with irradiation time and the contact angle of water on the modified membrane surface decreased from 86° to 32° after 10 min of irradiation. The modified membrane showed good fouling resistance. First, the adsorption amount of bovine serum albumin (BSA) on the membranes decreased from 159 ± 2 μg/cm2 to 13 ± 2 μg/cm2 after 10 min of grafting. Secondly, the filtration of a 0.1% BSA solution showed that the modified membrane had lower BSA adsorption and better flux recovery. Compared with the non-modified PVDF membrane, the fouling degree of the blend membrane with 7 min grafting was reduced by 66% and the flux recovery after chemical cleaning increased about 32%.