Dimethyl Dihydroacridines as Photocatalysts in Organocatalyzed Atom Transfer Radical Polymerization of Acrylate Monomers

Development of photocatalysts (PCs) with diverse properties has been essential in the advancement of organocatalyzed atom transfer radical polymerization (O‐ATRP). Dimethyl dihydroacridines are presented here as a new family of organic PCs, for the first time enabling controlled polymerization of challenging acrylate monomers by O‐ATRP. Structure–property relationships for seven PCs are established, demonstrating tunable photochemical and electrochemical properties, and accessing a strongly oxidizing 2PC.+ intermediate for efficient deactivation. In O‐ATRP, the combination of PC, implementation of continuous‐flow reactors, and promotion of deactivation through addition of LiBr are critical to producing well‐defined acrylate polymers with dispersities as low as 1.12. The utility of this approach is established through demonstration of the oxygen‐tolerance of the system and application to diverse acrylate monomers, including the synthesis of well‐defined di‐ and triblock copolymers. Polymere im Fluss: Organische Photoredoxkatalyse wurde zur kontrollierten Synthese von Poly(acrylaten) angewendet. Dieser Fortschritt wurde möglich durch die Entwicklung neuer organischer Photoredoxkatalysatoren – Dimethyldihydroacridine – mit einzigartigen Eigenschaften. Die Anwendung auf Durchflussreaktoren ist ebenfalls entscheidend für den Erfolg der Methode.