Biomass-Derived 2-Cycloolefin-1-ones: A Key to Depolymerizable and Degradable Polymeric Materials

The upcycling of polymeric materials, which enables the full recovery of carbon resources or energy from waste, is increasingly critical for mitigating the environmental impact of plastic disposal. However, endowing polymers with efficient depolymerization or degradation capability remains a formidable challenge. Here, we report a strategy based on the polymerization of 2-cycloolefin-1-one monomers characterized by low ring strain energies. The resulting polymers can be selectively depolymerized into their original monomers or otherwise degraded under mild conditions after use. This fully closed-loop, carbon-conserving recycling protocol offers a practical and sustainable solution. Notably, these monomers can be derived from biorefinery platforms, reducing the reliance of polymeric materials on fossil fuels. The polymers derived from 2-cycloolefin-1-ones exhibit material properties akin to conventional plastics. The precisely controlled C=C configuration and the presence of rigid cyclic units along the backbone impart high thermal transition temperatures, meeting the performance requirements for commodity materials. Beyond highly efficient depolymerization to monomers, which achieves true circularity, the strategic retention of evenly spaced carbonyl (ketone) groups adjacent to C=C bonds in the main chain provides versatile and complementary degradation pathways for polymeric plastics and thermosets.