Bisimidazolium PEG-mediated crosslinked 6FDA-durene polyimide membranes for CO2 separation

摘要

A series of bisimidazolium PEG-mediated crosslinked polyimides (BI-PEG-xPIs) with different PEG chain lengths were prepared for CO2 separation membranes. Both the ionic group (bisimidazolium) and PEG were used not only as CO2-solubilizing groups to enhance the CO2 selectivity but also as crosslinkers to inhibit plasticization. The crosslinked BI-PEG-xPI membranes displayed excellent chemophysical properties, together with high CO2/N-2 (up to 31) and CO2/CH4 (up to 46) permselectivities while maintaining high CO2 permeability (up to 350 Barrer) due to their high solubility and solubility selectivity. Moreover, the crosslinked membrane showed good plasticization resistance up to 25 atm. Finally, the chain length effects of the crosslinkers on the physicochemical properties and the gas separation performance of the corresponding membranes are also discussed.