Catalyst-Free Bulk Depolymerization of Polymethacrylates Prepared by ATRP.

Low-temperature depolymerization of ATRP polymers has been successfully demonstrated both in bulk and solution. However, all reported examples necessitate a metal catalyst for chain-end activation, require extensive modifications and transformations prior to depolymerization, or use specialized initiators. Herein, a catalyst-free bulk depolymerization method for poly(O-aryl methacrylates) is realized, whereby the elimination of lactonization lowers the temperature by more than 100 °C and enables up to 92% depolymerization efficiency at temperatures as low as 230 °C. Key to the approach is the in-situ thermal transformation of halogen chain-ends into macromonomer, resulting in monomer yields comparable to those obtained in the presence of a catalyst. The method can be expanded from various poly(O-aryl methacrylates) to conventional polymethacrylates, for example, poly(methyl methacrylate) and poly(benzyl methacrylate), after a short block addition of an O-aryl methacrylate. This work provides a straightforward, high-yielding, catalyst-free bulk method for chemical recycling and offers mechanistic insights into the thermal stability and depolymerization of ATRP polymers.