Photocatalytic Depolymerization of Commercial Polymethacrylates via a Solvent-Independent Pathway

Closed-loop chemical recycling of polymers with all-carbon backbones is an important component of plastic circularity but often requires either high temperatures (>400 °C) or noncommercial "designer" polymers. Although the feasibility of depolymerizing commercial poly(methyl methacrylate) at ≤150 °C was recently demonstrated, a large excess of (chlorinated) solvents was deemed essential to act as a radical source. Here, we report a novel and generalizable methodology that uses diverse commercial organic and inorganic photocatalysts to decouple catalytic reactivity from the solvent. This solvent-independent approach also allows for precise control over the radical flux in nonchlorinated media, achieving near-quantitative yields (>95%) even for challenging polymers like poly(benzyl methacrylate) and poly(2,2,2-trifluoroethyl methacrylate) that were previously difficult to process and depolymerize. Notably, our method is compatible with phase-changing solvents (liquid during reaction, solid at room temperature), which resolves the separation-temperature trade-off and allows straightforward, quantitative collection of regenerated monomers from a solid medium.