In this study, the task of integrating capture and conversion of CO2 into a single material platform is realized by developing bifunctional membranes based on polymer ionic liquids (PILs). The novelty of this work lies in the fabrication and comprehensive evaluation of PIL-based membrane materials that combine catalytic activity toward CO2 conversion with gas separation performance within one material system. In contrast to most previously reported imidazolium-based PILs, which have mainly been considered either as catalysts or as membrane materials, the present approach focuses on their dual functionality under both catalytic and gas transport conditions. A series of imidazolium-based PILs, including homopolymers and block copolymers with polystyrene, were synthesized. The materials were characterized to determine their catalytic activity during the cycloaddition of CO2 to epichlorohydrin and to determine their gas transport properties using pure gases (N2, O2, CO2) and a simulated dry flue gas mixture; membrane morphology was studied by scanning electron microscopy. Block copolymers exhibited higher catalytic conversions (up to 82.7%) than homopolymers, with selectivities above 93%. Chloride-containing block copolymers gave the best combination of CO2 permeability (up to 7.5 Barrer) and CO2/N2 selectivity (18–22) under mixed-gas conditions. Iodide-containing analogs demonstrated higher selectivity (up to 30) but lower CO2 permeability. Morphological analysis confirmed the presence of dense, defect-free structures in materials with the chloride anion, while materials with the iodide anion showed increased free volume and microheterogeneity. These results indicate that by altering the polymer and anion architecture, PIL-based membranes can effectively combine catalytic activity with selective CO2 transport, providing a promising avenue for enhancing carbon capture and utilization processes.
Atlaskina et al. (Sun,) studied this question.