Fabrication of microporous membranes by a feasible freeze method

Preparation of poly(vinylidene fluoride) (PVDF) microporous membranes with high water fluxes and excellent mechanical properties by a simple and effective freeze method was carried out in the present study. Dimethylsulfoxide (DMSO) was selected as a solvent, the solidification of casting solutions was achieved at a temperature of −10 °C with a refrigerator. The frozen solvent was exchanged with water and PVDF microporous membranes were formed at the same time. The structures and properties of the fabricated PVDF microporous membranes were investigated with scanning electron microscopy (SEM), X-ray diffraction (XRD), porosity, and water flux. It was observed that the formation of the spherulites throughout the PVDF membranes. The mechanical properties of PVDF membranes are dramatically enhanced, porosity and water fluxes of PVDF microporous membranes are gradually decreased with an increase of PVDF concentration in DMSO casting solutions. The freeze method was further developed as a general approach for fabricating cellulose acetate (CA), polyethersulfone (PES), and polyacrylonitrile (PAN) microporous membranes.