Experimental and theoretical study on dicationic imidazolium derived poly(ionic liquid)s for catalytic cycloaddition of CO2-epoxide

The development of novel and efficient catalysts for the cycloaddition of CO2-epoxide has attracted the interest of researchers. In this work, a series of dicationic vinyl-functionalized imidazolium ionic liquids (ILs) were prepared, then polymerized and further copolymerized with 1,4-divinylbenzene (DVB) by free radical reaction. The synthesized PIL-DVB-IV catalyst presented 93% yield and 99% selectivity to the product of propylene carbonate under the optimized reaction conditions of 110 °C, 2.0 MPa for 6 h. Besides, the PIL-DVB-IV catalyst exhibited excellent recyclability and generality to various epoxides. The potential energy surface of the catalytic reaction was given by the computation of Density Functional Theory (DFT), which further revealed the proton migration catalytic mechanism of PIL-DVB-IV catalyst. The kinetic process of the catalyst was illustrated through the study of catalytic reaction kinetics and the calculation of DFT.