Copper(II) Chloride/Tris(2-pyridylmethyl)amine-Catalyzed Depolymerization of Poly(n-butyl methacrylate)

A poly(n-butyl methacrylate) macroinitiator with terminal chlorine chain-end functionality (CEF) was depolymerized by ATRP mediated by a copper(II) chloride/tris(2-pyridylmethyl)amine (CuCl2/TPMA) catalyst at 170 °C. Depolymerization reactions with solid loadings between 8 and 21 wt % recovered >40% monomer within 10 min and up to 67% monomer at 8 wt % solid loading. This method was selective to n-butyl methacrylate monomer by concurrent depolymerization and distillation on a rotary evaporator. Control experiments confirmed that the reactions stopped due to the loss of CEF before equilibrium was established at the equilibrium monomer concentration. Incubation of the macroinitiators showed evidence of alkyl halide decomposition via lactonization of the chain end, leading to lower initiation efficiencies and an increase in the thermal stability of the polymer.