Ionic group-mediated crosslinked polyimide membranes for enhanced CO2 separation

Abstract

The dual cation-forming DABCO- or bisimidazolium-based ionic groups were introduced as crosslinkage sites and CO₂-solubilizing groups into 6FDA–durene polyimide (PI). The two resulting crosslinked PI membranes showed good chemical resistance to common polar organic solvents, along with excellent thermal and mechanical properties. Unlike other typical crosslinked polymers, the pendant ionic group-mediated crosslinked PI membranes, and in particular the DABCO-mediated crosslinked PI, displayed a very high CO₂ permeability of 469.4 Barrer, together with high CO₂/CH₄ (33.8) and CO₂/N₂ (23.1) permselectivities. In addition, these novel ionic group-mediated crosslinked PI membranes showed a high tolerance to plasticization by CO₂.