Swelling Poly(ionic liquid)s Tailored With Flexible Segment for Quasi-homogeneously Catalytic CO2 Conversion Into Cyclic Carbonates

Poly (ionic liquid)s (PILs) are promising catalysts for conversion of CO 2 and epoxides into cyclic carbonates, which could mitigate greenhouse effects while generating economic benefits. To achieve efficient utilization of active sites of PILs, a series of swelling PILs were synthesized in this work by copolymerization of ionic liquid monomer (EIL) with flexible polyethylene glycol dimethacrylate (PEGDMA) at varying molar ratio. The resulting swelling PILs showed significantly improved catalytic activity compared to nonswollen PEIL obtained by EIL self-polymerization. Additionally, a lower EIL/PEGDMA ratio during synthesis increased the flexible segment length between ionic liquid sites, which enhanced the swelling ability of PILs and further improved the catalytic activity. Among the synthesized PILs, the optimized P(EIL-co-EG)1.0, which showed the strong swelling ability, achieved catalytic performance comparable to that of monomers homogeneous catalysis, yielding 93.4% PC under the reaction conditions optimized (120°C, 1.5 mol% catalyst, 2 MPa CO 2 , 3 h). Furthermore, P(EIL-co-EG)1.0 demonstrated broad substrate scope toward various epoxides. Finally, based on FT-IR and NMR spectroscopy, a plausible catalytic mechanism was proposed. This study offers valuable insights into the enhancement of heterogeneous catalyst efficiency and the rational design of quasihomogeneous catalytic systems. Graphical A series of PILs with tailored swelling abilities were synthesized by copolymerizing ionic liquid monomers with flexible polyethylene glycol dimethacrylate at varying molar ratios, which aimed to achieve full utilization of PILs internal active sites and quasihomogeneously catalytic conversion of epoxides and CO 2 to cyclic carbonates.