In Situ Modification Assisted by HAT Chemistry for the Main Chain Initiated Depolymerization of Polymethacrylates

In this study we present a novel strategy to enhance the depolymerization of nonfunctionalized poly(methyl methacrylate) (PMMA) by enabling <i>in situ</i> activation of the polymer backbone using photoinduced Hydrogen Atom Transfer (HAT) chemistry. By screening various disulfide-based RAFT agents, we identified the commercially available bis(dodecylsulfanylthiocarbonyl) disulfide (DisRAFT-1) as the most effective, achieving up to 53% monomer recovery within 5 h at 150 °C under 405 nm light irradiation in tetrachloroethane (TCE). A systematic investigation of key reaction parameters, including DisRAFT-1 loading, temperature, and polymer concentration (10-200 mM), demonstrated the efficiency and versatility of the approach. Importantly, we highlight that light, elevated temperature, and a chlorinated solvent are all essential to initiate depolymerization. Moreover, temporal control over the process was achieved via light ON/OFF cycles, enabling on-demand depolymerization. This work offers a promising route toward chemical recycling of nonfunctionalized polymers by leveraging <i>in situ</i> backbone activation under mild and tunable conditions.