15/8/2014 · The dope solutions were first prepared by dissolving 15 wt.% PVDF in the solvent mixture of N, N-dimethylacetamide (DMAC) and acetone (50/50 wt.%), different amounts of PTFE micro-powders at 0, 3, 6 and 12 wt.% were added into the dope solutions to enhance the hydrophobicity of the membrane