Ultrafast Thermal RAFT Depolymerization at Higher Solid Contents

Abstract

Although thermal solution RAFT depolymerization has recently emerged as an efficient chemical recycling methodology, current approaches require specialized solvents (i.e., dioxane), typically suffer from extended reaction times, and operate exclusively under highly dilute conditions (i.e., 5 mM repeat unit concentration). To circumvent these limitations, a commercial radical initiator is introduced to kinetically untrap the depolymerization and promote chain-end activation. By varying the initiator concentration, a remarkable rate acceleration (up to 72 times faster) can be observed, enabling the completion of the depolymerization within 5 min. Notably, a 20-fold increase in the repeat unit concentration did not appreciably compromise the final depolymerization yield, while very high percentages of monomer could be recovered in a wide range of solvents, including dimethyl sulfoxide, anisole, xylene, acetonitrile, toluene, and trichlorobenzene. Our findings not only offer intriguing mechanistic aspects, but also significantly expand the scope and applications of thermal RAFT depolymerization.