粗糙基底辅助相转化法制备高度疏水PVDF微孔膜

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

提出一种高度疏水PVDF微孔膜的制备方法.以不同型号的耐水砂纸为模板,采用粗糙基底辅助相转化法制备高度疏水微孔膜,制膜体系为聚偏氟乙烯(PVDF)/N,N二甲基乙酰胺(DMAc)/正辛醇(octanol),凝胶剂依次为湿空气及去离子水.接触角实验结果表明,膜底面与水的接触角随着所用砂纸模板粗糙度的增加先增大后略有下降,其中1 000目的耐水砂纸基底制得的膜底面与水的接触角可达135°,显示出高度疏水性.研究发现,粗糙基底提供了膜底面的微米级粗糙度,同时,粗糙基底与非溶剂添加剂的协同作用延缓了相转化速率,促进了聚合物结晶和晶粒粗化,从而在膜底面生成了微纳复合阶层结构,提高了疏水性.与在玻璃基底上制得的膜的综合性能对比表明,本文制得的高度疏水微孔膜更适于在气液膜接触器中使用.

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 .