Pyridine N-Oxide Catalyzed Living Radical Polymerization of Methacrylates via Halogen Bonding Catalysis

The paper reports the generation of a carbon-center radical (R^•) from an alkyl iodide (R-I) via a halogen bonding catalysis using pyridine N-oxide (PO) catalysts. The use of this catalysis in organocatalyzed living radical polymerization was systematically studied over a series of substituted POs. A more electron-donating substitute led to a higher catalytic activity, as experimentally observed and theoretically supported by DFT (density functional theory) calculation. Notably, the polymerization was induced and controlled not only by thermal heating but also by photoirradiation. The polymerization was compatible with several functional monomers and afforded block copolymers.