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 in situ 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 in situ backbone activation under mild and tunable conditions.