Organocatalyzed Atom Transfer Radical Polymerization Catalyzed by Core Modified N-Aryl Phenoxazines Performed under Air

Organocatalyzed atom transfer radical polymerization (O-ATRP) was performed under air using core modified N-aryl phenoxazines as photoredox catalysts (PCs) to synthesize poly(methyl methacrylate) in a controlled fashion with initiator efficiency (I* = M-n,M-theo/M-n x 100) ranging from 84 to 99% and dispersity being similar to 1.2-1.3. Reduction of the reaction vial headspace was key for enabling the polymerization to proceed in a controlled fashion, as has been observed in Cu catalyzed controlled radical polymerizations. The ability to synthesize block copolymers and turn the polymerization on and off via manipulation of the light source was demonstrated. Six core modified N-aryl phenoxazines were able to catalyze O-ATRP under air, albeit with most PCs achieving I*s similar to 5% lower under air compared to when the reaction was performed under nitrogen.