Cationic Polymerization via Activation of Alkoxyamines Using Photoredox Catalysts

Cationic polymerization via mesolytic cleavage of alkoxyamines was investigated using photoredox catalysts under irradiation with visible light of various wavelengths. The carbon–oxygen bond of the alkoxyamine derived from p‐methoxystyrene (pMOS) and (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) was cleaved by an excited cationic iridium catalyst under blue LED irradiation to generate the pMOS cation, which efficiently initiated the cationic polymerization of vinyl ethers and styrene derivatives to give the polymers with a pMOS unit at the initiating end. Temporal control of the polymerization was achieved by switching the light on and off. Poly(pMOS) with a terminal TEMPO unit obtained by nitroxide‐mediated radical polymerization was subsequently employed as a macroinitiator for the photoredox‐catalyzed cationic polymerization to afford block copolymers via a mechanistic transformation from radical to cationic polymerization using alkoxyamine as the mutual initiating site.