Angewandte Chemie | 2019
A Facile Photocontrolled Iodine-Mediated Reversible-Deactivation Radical Polymerization System: Solution Polymerization of Methacrylates under Irradiation with NIR LED Light.
Abstract
Herein, near-infrared (NIR) photocontrolled iodine-mediated reversible-deactivation radical polymerization (RDRP) of various methacrylates without external photocatalyst was developed using alkyl iodide (e.g., 2-iodo-2-methylpropionitrile, CP-I) as the initiator at room temperature. We report the first example of using a series of special solvents containing carbonyl groups \xa0(e.g., 1,3-dimethyl-2-imidazolidinone (DMI), N,N-dimethylacetamide (DMAc), tetramethylurea (TMU), 1,3-dimethyl-tetrahydropyrimidin-2(1H)-one (DMPU), and N-methyl pyrrolidone (NMP)) as both solvent and catalyst for photocontrolled RDRP under irradiation with a long wavelength (λmax = 730 nm) light-emitting diode (LED) light. Therefore, the NIR photocontrolled polymerization system has the simplest components: 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 promising NIR photocontrolled iodine-mediated RDRP system were confirmed by polymerization kinetics, multiple controlled on-off light switching cycle regulation, and chain extension experiments. Importantly, the barrier penetration photopolymerizations were also proceeded successfully with various thickness of skin of pork and A4 paper to demonstrate the unique advantages of this simplest polymerization system, which benefitting from the high penetration of NIR light.