Visible light-induced living/controlled cationic ring-opening polymerization of lactones

Ring-opening polymerization of lactones has served as one of the most resourceful and versatile methods for the production of polyesters. However, the photocontrolled ring-opening polymerization of lactones with the advantages of being inexpensive, green, and noninvasive, is still rarely reported. In this work, we developed a series of composite photoacid generators containing a common photocatalyst and an onium salt to induce the living/controlled cationic ring-opening polymerization of lactones using benzyl alcohol or butyl alcohol as an initiator under visible light. The wavelength of the light could be easily adjustable by applying different photocatalysts. Moreover, radical species are generated concurrently during the electron transfer processes; as a result, simultaneous living/controlled cationic ring-opening polymerization of lactones and reversible addition-fragmentation chain transfer radical (RAFT) polymerization can be performed using hydroxy group capped trithiocarbonate to produce hybrid block copolymers.