Advances in modification methods of polyimide membranes for gas separation

Polyimide have the good chemical and thermal stability,excellent mechanical properties and higher Fractional Free Volume(FFV),which results in both high gas permeability and high selectivity.Therefore,polyimide membranes are widely used in gas separation applications.However,the gas transport performance of polyimide membranes needs to be improved for the stricter requirements from industry.Besides,most of the synthesized polyimide for separating gas mixtures containing the condensed gas will face the problem of plasticization which makes their performance decay and hinders their further application.Therefore,in order to use polyimide-based separation membrane economically and effectively,the significant studies have been carried out to enhance their gas transport performance and improve their anti-plasticization properties by physical or chemical modification methods.This paper reviews the latest progress in polyimide modification approaches for gas separation applications,in which cross-linking and blending modification methods are focused.At last,the future directions of polyimide-based gas separation membranes are predicted and suggested.