Bulk Depolymerization of Polystyrene with Comonomer Radical Triggers

This study introduces a novel approach to depolymerize polystyrene in the absence of solvent at significantly reduced temperatures through the incorporation of a thermally labile comonomer. Specifically, we employ <i>N</i>-(methacryloxy)phthalimide (PhthMA) as a comonomer with an activated ester capable of thermally triggered decarboxylation. Thermal treatment enables the generation of backbone radicals that promote <i>β</i>-scission and subsequent unzipping. These polystyrene analogs depolymerize with up to 91% reversion to monomer in under 2 h at temperatures significantly lower than those required for conventional polystyrene. As compared to depolymerization triggered by decarboxylation at the <i>ω</i>-chain end, this pendent-group approach was considerably more efficient. The recovered styrene monomer from the bulk depolymerization of poly(styrene-<i>co</i>-PhthMA) copolymers can undergo direct repolymerization, yielding new styrenic materials. This comonomer strategy extends across various styrenic copolymers, highlighting its potential as a broadly applicable method for initiating depolymerization among vinyl polymer classes.