Preparation of imidazole-based polymeric ionic liquid catalysts and their catalysis in the copolymerization with sulfur dioxide

Sulfur dioxide (SO 2 ) is one of the primary air pollutants, and its reaction with epoxides to produce sulfur-containing polymers is an efficient means of resource utilization for SO 2 , however, catalysts play a crucial role in this reaction. Polymeric ionic liquids (PILs) have become a hot topic in catalysis research due to their dual characteristics of ionic liquids and polymers. Therefore, a series of heterogeneous PILs were prepared, characterized, and employed for the copolymerization of SO 2 with epoxides in this study. The impact of different halide anions and hydrogen bond donors on catalytic performance was investigated. Optimal reaction conditions for copolymerization were determined by examining reaction temperature, reaction time, molar ratio of catalyst to epoxide, and other factors. Furthermore, PILs demonstrated recyclability for more than 6 cycles without a significant decrease in catalytic activity, and PILs exhibited broad applicability to various epoxides. Finally, density functional theory (DFT) calculations were employed to further elucidate the activation effect of halide anions and hydrogen bond donors on epoxides to propose a potential mechanism for the copolymerization of SO 2 with epoxides catalyzed by PILs.