采用两步法制备得到聚酰亚胺（PI）纳滤膜，探究了前聚体聚酰胺酸（PAA）分子量对制得PI膜结构与性能的影响。通过调控单体投料比得到不同分子量的前聚体PAA，经亚胺化得到PI膜，最后考察其耐溶剂耐高温性能。结果表明，随PAA分子量增大，PI膜表面由多孔变为致密，通量下降；在一定PAA分子量范围内，对固绿（MW808）的截留率上升，从68.2%增加到93.8%；当PAA分子量进一步增加时截留率保持不变。对制得PI膜进行耐溶剂耐高温测试，发现 PI膜在有机溶剂和高温环境中均能保持较好的稳定性，并且随PAA分子量增大，PI膜的化学稳定性和热稳定性增强。由较高PAA分子量制备的PI膜在有机溶剂中对固绿截留率保持在85%以上，高温环境中几乎保持不变。

In this paper, polyimide (PI) solvent-resistant nanofiltration membranes were fabricated by a two-step method. The effect of precursor molecular weight on the structure and performance of PI membranes was investigated. The polyamic acid (PAA) precursors with different molecular weight were synthesized by changing the ratio of PMDA and ODA. The chemical and thermal stability of PI membranes were investigated. The results showed that the increasing molecular weight can help to make a membrane with a denser skin layer as well as a lower flux. In a range of PAA molecular weight, the FCF rejection increased from 68.2% to 93.8% when the molecular weight increased. And then the rejection was nearly unchanged with the increasing molecular weight. The membranes can be stable both in most organic solvent and high temperature. The results indicated that the chemical and thermal stability of PI membranes increased with the increasing molecular weight of PAA. The FCF rejection of PI membranes prepared from high PAA molecular weight kept higher than 85% in most organic solvent and almost the same in high temperature
 

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