Efficient catalytic depolymerization of high-molecular-weight PMMA under low-temperature and high-concentration conditions

Abstract

To help alleviate resource waste and environmental pollution from discarded poly(methyl methacrylate) (PMMA), we demonstrate facile synthesis and efficient catalytic depolymerization of high-molecular-weight PMMA. A small fraction of C–Me bonds are replaced with catalytically activatable C–Cl bonds via free radical copolymerization of MMA with readily available methyl α-chloroacrylate. Leveraging low-temperature efficient catalysis by Cu(0), the synthesized polymers achieve high recyclability while maintaining ideal intrinsic properties. For PMMA with M_n exceeding 300 kg mol⁻¹ (380–1010 kg mol⁻¹), Cu(0)-catalyzed depolymerizations attain the highest reported depolymerization efficiency (∼90% in 4 hours) at a temperature well below 200 °C (160 °C) and high concentrations ([MMA unit]₀ = 400–8800 mM). The recovered MMA monomer can be effectively repolymerized into a polymer with molecular weight and properties comparable to those of the polymer synthesized from a virgin monomer, and both catalysts and solvents used in this approach exhibit potential for recyclability.