Formation of a High Hydrophobic PVDF Microporous Membrane by Non-solvent Induced Phase Inversion Assisted With Coarse Substrate

A novel method was proposed for fabricating high hydrophobic polyvinylidene fluoride (PVDF) membrane.Waterproof abrasive paper was used as mold which had a micrometer-sized morphology.N,N-dimethylacetamide (DMAc) and 1-octanol were used as solvent and non-solvent addition,respectively.The PVDF membrane was fabricated on the mold by using phase inversion method induced by the penetration of water vapor and then water precipitation bath.Contact angle measurement showed that the water contact angle on the bottom surface of the membrane increased and then decreased slightly with the increase of roughness of the abrasive paper used,among which the WCA on the bottom surfaces prepared with type of 1000-grit waterproof abrasive paper reached as high as 135°.It was revealed that the microstructure level roughness was replicated from the course substrate.And the course substrate acted in synergy with non-solvent additive,which promoted the solid-liquid demixing and radial growth of the polymer crystallites in all directions.The resulting micro-and nanoscale hierarchical roughness on the bottom surface brought about an enhanced hydrophobicity of the membrane.The characterization of the porous PVDF membrane obtained from coarse substrate and glass substrate was carried out by a nitrogen flux measuring and a mechanical property test.It shows that the highly hydrophobic membrane by using the novel method is more suitable for membrane contactor devices.