This work provides a novel approach to improve the separation performance of PVDF membranes.Poly(vinylidene fluoride)-graft-poly(methyl methacrylate) (PVDF-g-PMMA) copolymers were synthesized via grafting methyl methacrylate (MMA) onto PVDF.Benzoyl peroxide (BPO) was the initiator

and the PVDF was initially modified by tetraethyl ammonium hydroxide (TEAH) in the liquid phase.The copolymer was cast into a flat membrane via immersion phase inversion.The structure and performance of as-prepared membranes were characterized by FTIR

SEM and filtration experiments.Simultaneously

the effects of the concentration of TEAH and the modifying time on surface contact angle were examined.The results indicate that the PVDF formed C C double bonds following dehydrofluorination by TEAH.MMA was grafted onto the modified PVDF backbones

forming a homogeneous pore distribution in the interior and exterior of the membrane.The water contact angle of PVDF-g-PMMA membranes decreased with increasing the TEAH concentration and modifying time.The hydrophilicity of the modified PVDF was the best with 2.0 wt% of TEAH solution at 50℃ for 20 min

under these conditions the grafting degree of membrane was 27.1%

the porosity and mean pore size were 71.6% and 78.9 nm

respectively; the contact angle was 55.9 and decreased to 0 within 50 s; the water flux increased to 665.34 L/(m2h) and the rejection ratio and flux recovery ratio were up to 95.6% and 90.1%

respectively.The separation performance of the PVDF-g-PMMA membrane was significant improvement compared to that of the pure PVDF membrane.