Organocatalytic PET-RAFT polymerization with a low ppm of organic photocatalyst under visible light

Abstract

The development of light-mediated controlled radical polymerization has benefited from the discovery of novel photocatalysts, which could allow precise light control over the polymerization process and the production of well-defined polymers. Here, we introduce oxygen-doped anthanthrene (ODA) as an effective organic photocatalyst for photoinduced energy/electron transfer reversible addition–fragmentation chain-transfer (PET-RAFT) polymerization. ODA photocatalysts feature strong visible light absorption (ε_{455 nm} up to 2.4 × 10⁴ M⁻¹cm⁻¹), ease-of-synthesis, a certain oxygen tolerance, and high stability, which enable the photo-regulated RAFT polymerization with an extremely low catalyst loading (0.1–10 ppm) and excellent control under visible light or sunlight. Furthermore, this organocatalytic living radical process is adaptable to the polymerization of a range of monomers including methyl methacrylate, butyl acrylate, styrene, and N,N-dimethyl acrylamide, and also the synthesis of diblock and decablock copolymers under metal-free conditions.