以聚醚砜(PES)为膜材料,DMAc为溶剂,研究了3种非溶剂添加剂(NSA)--EgOH、DegOH和BuOH在水和NSA中凝胶对平板微孔膜性能的影响.利用浊点法得到PES/DMAc/NSA和PES/DMAc/NSA/H2O体系25℃的相图;并以邻近比α值来表征膜溶液组成点靠近相分离的程度.添加了NSA的铸膜液在水中凝胶制备微孔膜,以EgOH为非溶剂添加物,在相同聚合物浓度、相同凝胶条件下,仅仅改变铸膜液的邻近比可以获得成倍透量差别的微孔膜;随α的增加,膜结构从指状孔结构变化到海绵结构.结果表明,NSA的影响不是以量来表征的,而是受控于溶液的邻近比α.铸膜液组成邻近浊点曲线,发生快速相分离有利于制备高透量的微孔膜.以DegOH为NSA,当铸膜液α值高时,可以获得高透量的微孔膜.考察不同NSA作凝胶剂对膜性能的影响,发现微孔膜的透量不仅取决于膜孔的大小,也决定于膜孔之间的相互连通性.膜孔之间的相互连通性是由凝胶相转化过程中溶剂的溢出速率和膜结构固化前铸膜液剩余溶剂含量决定的.
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