Efficient and Selective Chemical Recycling of CO2-Based Alicyclic Polycarbonates via Catalytic Pyrolysis

Chemical recycling of polymers to their constituent monomers is the foremost challenge in building a sustainable circular plastics economy. Here, we report a strategy for highly efficient depolymerization of various CO2-based alicyclic polycarbonates to epoxide monomers in solvent-free conditions by a simple Cr-III-Salen complex mediated catalytic pyrolysis process. The chemical recycling of the widely studied poly(cyclohexene carbonate) exhibits excellent reactivity (TOF up to 3000 h(-1), 0.1 mol % catalyst loading) and high epoxide monomer selectivity (>99 %). Mechanistic investigation reveals that the process proceeds in a sequential fashion via a trans-carbonate intermediate.

Automated summary

This study reports a highly efficient chemical recycling method to depolymerize CO2-based alicyclic polycarbonates into epoxide monomers. The method is solvent-free and exhibits excellent reactivity and high epoxide monomer selectivity.