Highly Selective Preparation and Depolymerization of Chemically Recyclable Poly(cyclopentene carbonate) Enabled by Organoboron Catalysts.

Poly(cyclopentene carbonate) (PCPC) produced by copolymerization of CO 2 and cyclopentene oxide (CPO) is a promising but challenging chemical recyclable polymer that has high potential in minimizing plastic pollution and maximizing CO 2 utilization. Currently, problems remain to be solved, include low reactivity of toxic metal catalysts, inevitable byproducts, and especially the ambiguous mechanism understanding. Herein, we present the first metal-free access to PCPC by using a series of modular dinuclear organoboron catalysts. PCPC was afforded in an unprecedented catalytic efficiency of 1.0 kg of PCPC/g of catalyst; while the depolymerization of PCPC abides by a combination pathway of random chain scission and chain unzipping, returning CPO in near-quantitative yield (>99 %). The preparation and depolymerization of PCPC along with in depth understanding of related mechanisms would be helpful for further development of advanced catalysts and recyclable plastics.