有机溶剂对PVDF铸膜液热力学性质及其膜结构性能的影响

考察了10种小分子有机溶剂添加剂对PVDF／DMAc制膜体系热力学与膜结构的影响。结果发现，小分子有机溶剂添加剂使铸膜液体系的凝胶值降低，即热力学稳定性降低。当铸膜液中添加了EtOH、i-PrOH、PgOH、PtOH时，膜中指状大孔结构充分发展，并且膜的孔隙率高、气通量大。而DtOH、BtOH、OtOH、PrA、AC和MeAt添加剂则使得大孔的结构减少，并且孔隙率低、气通量小。最后从热力学性质与扩散两个角度进行了成膜机理的探讨，当使用EtOH、i-PrOH、PgOH、PtOH添加剂时，铸膜液中由于PVDF超分子聚集态结构的生成使得体系的耐非溶剂性能大大降低，也正是铸膜液中存在的PVDF超分子聚集态结构使得扩散速度加快，分相速度提高，于是大孔结构得到发展。

The influence of organic solvents additives on the thermodynamics for PVDF casting solution and the membrane morphology and properties

This paper investigated the influences of ten types of low molecules organic solvents on the thermodynamics of PVDF casting solutions and membrane structures. The results showed that the coagulation values decreased and the thermodynamics of the membrane-forming systems became worse when the low molecules organic solvents were used as additives. When EtOH, i-PrOH, PgOH, PtOH were added to the PVDF/DMAc solutions, the finger-like macrovoids in the membranes expanded fully with high porosity and high gas fluxes. But DtOH, BtOH, OtOH, PrA, Acand MeAt additives restrained the development of the macrovoids, and then the porosity and gas fluxes were low. The membrane formation mechanism was discussed from the thermodynamic and diffusion aspects. When EtOH, i-PrOH, PgOH, PtOH were joined into the casting solutions, PVDF aggregate structure formed and the resistance-solvent property of the casting solution reduced. It was the aggregate structures that made the diffusion velocity increase, then the phase separation rate was improved and the macrovoids was developed.