Hypercrosslinked mesoporous poly(ionic liquid)s with high ionic density for efficient CO2 capture and conversion into cyclic carbonates

Abstract

Mesoporous poly(ionic liquid)s (MPILs), featuring a high specific surface area and efficient active sites, are promising candidates for simultaneous CO₂ capture and conversion. Herein, a family of sponge-like hypercrosslinked imidazolium-based MPILs with different ionic densities were successfully prepared by free-radical polymerization and subsequent supercritical CO₂ drying (SCD). Among these MPILs, PVIm-6-SCD from a monomer which was produced from the reaction of 1-vinyl-1H-imidazole with 1,2,3,4,5,6-hexakis(bromomethyl)benzene and has the highest ionic density (six ion pairs) displayed unprecedentedly high CO₂ adsorption: 3.60 mmol g⁻¹ at 273 K and 1 atm. What's more, PVIm-6-SCD, revealed as one of the most efficient catalysts compared to those reported in the literature, can efficiently convert CO₂ by cycloaddition with various epoxides into cyclic carbonates at atmospheric pressure, even under relatively low temperature, solvent-free, metal-free and additive-free conditions because of its abundant mesopores providing a large specific surface area and high ionic density providing rich exposed bromide anions as active sites, as well as high CO₂ adsorption capacity. Moreover, it can be easily separated with good reusability. This work highlights hypercrosslinked MPILs as a versatile platform to achieve efficient CO₂ capture and conversion under mild conditions.