Abstract:Poly(vinylidene fluoride) (PVDF) membranes were prepared via non solvent induced phase separation method (NIPS). The effects of the mass ratio of poly(ethylene glycol) (PEG200) to N,N-dimethylacetamide (DMAc) on the demixing rate and the performances of PVDF membrane were studied. The effects of triethyl phosphate (TEP)-DMAc mixed solvents on the precipitation rate of PVDF solutions, the membrane morphology and the membrane performances were discussed. The addition of PEG200 to the casting solution leads to the weakened solvent power to polymer, which causes an instantaneous demixing and a higher flux. The casting solution viscosity increases with the increase of TEP content in the mixed solvent, which results in a slower demixing rate during the precipitation process. Cellular pores on top surface decreases with the increase of m(TEP)/m(DMAc), and finger-like voids gradually disappear. At the same time, the sponge like structure formed and the flux and mechanical property of the membrane are improved.