Tuning Anion Chemistry and Ionic Liquid Incorporation in Poly(ionic liquid)s Membranes for Enhanced CO ₂ Separation

Owing to the tunability of both cations and anions, as well as the strong CO2 affinity of amino groups, three amino-functionalized novel poly(ionic liquid)s (PILs) were designed and employed to fabricate composite membranes by casting the synthesized PIL solutions onto polysulfone ultrafiltration supports. The effect of different chemical structures on the separation performance of NH2-carrier-based membranes was systematically investigated. The optimized membrane exhibited a CO2 permeance of 9.3 GPU together with an outstanding CO2/N2 selectivity of 106, achieved by incorporating amino-based ILs as mobile carriers. This outstanding performance arises from the synergistic effect of fixed-site carriers in the PILs and mobile carriers in the IL, which together promote CO2-facilitated transport. These results suggest that the developed membranes may provide an energy-efficient route for industrial CO2 capture.