Temporal Regulation of PET-RAFT Controlled Radical Depolymerization

A photocatalytic RAFT-controlled radical depolymerization method is introduced for precisely conferring temporal control under visible light irradiation. By regulating the deactivation of the depropagating chains and suppressing thermal initiation, an excellent temporal control was enabled, exemplified by several consecutive "on" and "off" cycles. Minimal, if any, depolymerization could be observed during the dark periods while the polymer chain-ends could be efficiently re-activated and continue to depropagate upon re-exposure to light. Notably, favoring deactivation resulted in the gradual unzipping of polymer chains and a stepwise decrease in molecular weight over time. This synthetic approach constitutes a simple methodology to modulate temporal control during the chemical recycling of RAFT-synthesized polymers while offering invaluable mechanistic insights. Precise temporal control under visible irradiation has been achieved through a photocatalytic RAFT chemical recycling methodology. Depolymerization could be easily initiated by switching "on" the light, whereas negligible monomer regeneration was observed in the dark. This outstanding characteristic was possible by fine regulation of the deactivation of the depropagating chain and by finally suppressing thermal initiation of the chains.image