Interconvertible and switchable cationic/PET-RAFT copolymerization triggered by visible light

Abstract

In this work, photoswitchable and interconvertible cationic/radical copolymerization was investigated by combining a Lewis acid-catalyzed cationic polymerization with a photoinduced electron/energy transfer (PET)-reversible addition-fragmentation transfer (RAFT) polymerization, in which the dormant terminal group of the RAFT polymerization was employed as the dual mediator for cationic and photoradical polymerizations. The photoredox catalyst, a zinc porphyrin complex (ZnTPP), was tested with a series of Lewis acids. When coupled with a boron-based Lewis acid, B(C6F5)3, the concurrent and interconvertible cationic/radical copolymerization of vinyl ether and methyl acrylate successfully proceeded in a controlled manner under visible light irradiation, in which the ratio of the generation of cationic and radical species was controlled by irradiation with different wavelengths of visible light. Photoswitchable and interconvertible cationic/radical copolymerization was investigated by combining a Lewis acid-catalyzed cationic polymerization with a photoinduced electron/energy transfer (PET)-reversible addition-fragmentation transfer (RAFT) polymerization, in which the dormant terminal group of the RAFT polymerization was employed as the dual mediator for cationic and photoradical polymerizations. Zinc porphyrin complex (ZnTPP) as the photoredox catalyst and bulky boron-based Lewis acid, B(C6F5)3, was successfully combined to induce the concurrent and interconvertible cationic/radical copolymerization of vinyl ether and methyl acrylate under visible light irradiation.