N,N-Diaryl Dihydrophenazines as Photoredox Catalysts for PET-RAFT and Sequential PET-RAFT/O-ATRP

N,N-Diaryl dihydrophenazines are employed as organic photoredox catalysts (PCs) for photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. The ability of these PCs to mediate PET-RAFT is heavily dependent on the ability of the PC to access a photoexcited intramolecular charge transfer state. The use of PCs displaying intramolecular charge transfer in the excited state allows for efficient PET-RAFT of a variety of monomers, including vinyl acetate, and in a wide range of solvents. The ability of these PCs to also mediate organocatalyzed atom transfer radical polymerization (O-ATRP) is exploited to perform a sequential PET-RAFT/O-ATRP block copolymerization of PMA-b-PMMA using the same PC for both polymerizations.