Depolymerization of P(PDMS11MA) Bottlebrushes via Atom Transfer Radical Polymerization with Activator Regeneration

Depolymerization of vinyl polymers into monomers is energy-intensive due to the high thermal and chemical stability of the backbone. Depolymerizations of methacrylic polymers are typically conducted above the ceiling temperature and thermal degradation temperature to degrade polymers by bond scission. This work investigates the catalyzed depolymerization of a Cl-capped poly(poly(dimethylsiloxane) methacrylate) (P(PDMS11MA-Cl)) polymer mediated by an atom transfer radical polymerization catalyst: copper(II) chloride/tris(2-pyridylmethyl)amine (CuCl2/TPMA) at 170 °C. The depolymerization yield, rate, and selectivity were improved by increasing the ratio of [TPMA]/[CuCl2]. Electron transfer from the ligand contributed to the Cu(I) activator (re)generation at high temperature (T> 130 °C), as proven by ultraviolet-visible spectroscopy. The bottlebrush could be partially depolymerized and repolymerized over a few cycles.