Imidazolium and pyridine bifunctionalized hypercrosslinked polymers as efficient and recyclable catalysts for CO2 cycloaddition

Converting CO₂ into precious chemicals is considered to be a fundamental and effective tool for controlling the abundant CO₂ emitted. One of the most compelling methods for CO₂ conversion is the synthesis of cyclic carbonates by cycloaddition of CO₂ with epoxides. However, the development of materials with specific functionalities for CO₂ capture and conversion is still considered to be a significant challenge. Herein, a novel imidazolium salts and pyridine skeleton bifunctionalized hypercrosslinked polymers were prepared by FeCl₃-catalyted Friedel-Crafts alkylation reaction. Various analytical techniques were used to investigate the properties of the catalysts. The bifunctionalized heterogeneous catalysts exhibited outstanding catalytic performances for CO₂ cycloaddition under mild conditions with an excellent yield of up to 99 %. Besides, the catalyst could bear various epoxides and no significant loss of activity after 6 cycles. The properties of metal-free, solvent-free, cocatalyst-free, easy-to-prepare, mild conditions, facility separation and recyclability make the bifunctionalized hypercrosslinked polymers useful for CO₂ cycloaddition.