Photocontrolled Iodine-Mediated Reversible-Deactivation Radical Polymerization: Solution Polymerization of Methacrylates by Irradiation with NIR LED Light.

Herein, near-infrared (NIR) photocontrolled iodide-mediated reversible-deactivation radical polymerization (RDRP) of methacrylates, without an external photocatalyst, was developed using an alkyl iodide (e.g., 2-iodo-2-methylpropionitrile) as the initiator at room temperature. This example is the first use of a series of special solvents containing carbonyl groups (e.g., 1,3-dimethyl-2-imidazolidinone) as both solvent and catalyst for photocontrolled RDRP using long-wavelength (λmax =730 nm) irradiation. The polymerization system comprises monomer, alkyl iodide initiator, and solvent. Well-defined polymers were synthesized with excellent control over the molecular weights and molecular weight distributions (Mw /Mn <1.21). The living features of this system were confirmed by polymerization kinetics, multiple controlled "on-off" light switching cycles, and chain extension experiments. Importantly, the polymerizations proceeded successfully with various barriers (pork skin and A4 paper), demonstrating the advantage of high-penetration NIR light.