Abstract
It is highly desirable to reduce the environmental pollution related to the disposal of end-of-life plastics. Polycarbonates derived from the copolymerization of CO(2) and epoxides have attracted much attention since they can enable CO(2)-fixation and furnish biorenewable and degradable polymeric materials. So far, only linear CO(2)-based polycarbonates have been reported and typically degraded to cyclic carbonates. Here we synthesize a homogeneous dinuclear methyl zinc catalyst ((BDI-ZnMe)(2), 1) to rapidly copolymerize meso-CHO and CO(2) into poly(cyclohexene carbonate) (PCHC) with an unprecedentedly cyclic structure. Moreover, in the presence of trace amounts of water, a heterogeneous multi-nuclear zinc catalyst ((BDI-(ZnMe(2)·xH(2)O)) (n) , 2) is prepared and shows up to 99% selectivity towards the degradation of PCHC back to meso-CHO and CO(2). This strategy not only achieves the first case of cyclic CO(2)-based polycarbonate but also realizes the complete chemical recycling of PCHC back to its monomers, representing closed-loop recycling of CO(2)-based polycarbonates.