Ionic liquid polymer materials with tunable nanopores controlled by surfactant aggregates: a novel approach for CO2 capture

Abstract

Monomeric ionic liquids (ILs), ionic liquid polymers (ILPs) and IL-based composites have emerged as potential materials for CO₂ capture owing to their exceptional intrinsic physical solubility of CO₂. This study reports the development of novel IL polymer materials incorporating CO₂-philic tunable nanopores and their subsequent utilization for CO₂ capture. In this approach, primarily, micelles were formed in monomeric IL 1-vinyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)imide using a CO₂-philic surfactant (N-ethyl perfluorooctyl sulfonamide) through self-assembly, from which polymeric materials were fabricated via free radical polymerization. The CO₂ adsorption studies demonstrated 3-fold enhancements for the surfactant micelle incorporated IL polymers (SMI-ILPs) compared to their bare IL polymers. The SMI-ILPs were regenerated by simply heating at 70 °C and reused for 15 cycles with a retention of over 96% of CO₂ uptake capacity. The simple recovery and notable enhancements in CO₂ sorption of novel SMI-ILPs were traced to the adsorption of CO₂ at the (i) highly porous IL-based polymeric networks, and (ii) nanometer sized apolar pores made by CO₂-philic surfactant tails. This work will open up new possibilities for the development of IL based smart materials for CO₂ capture and separation.