铸膜液溶解温度对制备PVDF微孔膜结构的影响

Effect of Dissolving Temperature of Dopes on the Morphology of PVDF Membrane

铸膜液的溶解温度对浸没沉淀相转化法制备聚偏氟乙烯(PVDF)微孔膜结构具有显著影响。所成膜断面底层为胞腔状结构,胞腔直径的大小随铸膜液溶解温度的升高而增大,且胞腔表面为三维网络状结构。结合三元相图和膜的微观结构分析认为,该制膜体系成膜过程中首先发生双节液-液分相,贫聚合物相成核并粗化形成胞腔,继而发生旋节液-液微相分离。溶解温度对成膜结构的影响与PVDF分子和溶剂分子间的溶剂化作用、成膜过程中高分子线团的构象变化有关。

Poly（vinylidene fluoride）（PVDF） membranes were prepared by immersion precipitation method.Effects of polymer dissolving temperature of the dopes on the morphology of prepared membranes were examined.Polymer dissolving temperature is varied from 50 ℃ to 120 ℃.The membrane formation mechanism was analyzed theoretically.The binodal liquid-liquid demixing takes place first by nucleation and growth of droplets of a polymer poor phase,then spinodal liquid-liquid sub-demixing occurs.Which results in the cross section of the prepared membrane is composed of interconnected globule-like particulate,and the surface of the globules is bi-continuous network structures.With the increasing of the dissolving temperature of the dopes,the diameter of the globules becomes larger.The difference of the globules diameter for different dope dissolving temperature attributes to the solvent action of the system.