Oxygen-initiated radical ring-opening polymerization of macrocyclic allylic sulfides under ambient conditions

Abstract

Although radical ring-opening polymerization (ROP) is a powerful approach for synthesizing polymers with diverse backbone structures, the intrinsic oxygen sensitivity of radicals challenges the ability to perform these polymerizations under air conditions. Here, we reported a novel oxygen-initiated radical ROP of macrocyclic allylic sulfides that can efficiently proceed under an air atmosphere, enabling the construction of sulfur-containing polymers with moderate to high molecular weights. The versatility of this approach was further demonstrated by copolymerizing macrocyclic allylic sulfides with vinyl monomers to create degradable vinyl polymers under ambient conditions. Density functional theory calculations revealed that the quenching of radicals by oxygen in the chain-growth process was kinetically disfavored, thereby allowing the polymerization to be compatible with oxygen. This work will further advance applications of radical ROP in diverse fields by enhancing its tolerance towards oxygen.