基于异氰酸酯的可溶性聚酰亚胺的合成及其气体分离性能

Synthesis and Gas Separation Properties of Isocyanate-based Soluble Polyimide Membranes

针对传统聚酰亚胺(PI)分离膜对气体渗透系数低的问题,本文利用3,3',4,4'-二苯酮四羧酸二酐(BTDA)、甲苯二异氰酸酯(TDI)、二苯基甲烷二异氰酸酯(MDI)和四甲基苯二甲基二异氰酸酯(TMDXI)成功制备了新型可溶性PI分离膜。研究结果表明含四甲基侧基的TMXDI单体对PI分离膜的分子堆积结构、自由体积及分离膜的溶解性、力学性能及耐热稳定性等特性有显著的影响。随着TMDXI含量的增加,PI分离膜由脆性断裂转变为韧性断裂;同时,PI膜对不同气体分子的渗透性能均显著提高,当TMDXI添加量为30 mol%时,分离膜对CO_(2)的渗透系数提高了144%。

Series of soluble polyimides(PI)gas separation membranes were successfully synthetized by using 3,3',4,4'-benzophenonetetracarboxylic dianhydride(BTDA),tolylene-2,4-diisocyanate(TDI),diphenylmethane-4,4'-diisocyanate(MDI)and 1,3-bis(2-isocyanato-2-propanyl)benzene(TMDXI).It is shown that the incorporation of TMDXI has a great effect on the solubility,fractional free volume(FFV),tensile strength,and thermal resistance of resultant PI membranes.The fracture behavior of PI membranes transforms from brittle fracture to ductile fracture,and the permeabilities of PI membranes increases for various gases attributed to introduced TMDXI moiety,and especially,the permeability for CO_(2) of the PI membrane containing 30 mol%TMDXI increases 144%in relative to the sample without TMDXI.