Organocatalyzed Atom Transfer Radical Polymerization Driven By Visible Light

The development of atom transfer radical polymerization (ATRP) is among the most significant technological advancements of polymer science. However, contamination of the polymer by the metal catalyst remains a major limitation. Organic ATRP photocatalysts have been sought to address this difficult challenge, but have not achieved the precision performance of metal catalysts. Here, we introduce diphenyl dihydrophenazines, identified through computationally directed discovery, as a new class of strongly reducing photocatalysts. These metal-free catalysts achieve high initiator efficiencies to synthesize polymers with tunable molecular weights and extremely low dispersities, using visible light, including sunlight.