Development of a Robust Photocatalyzed ATRP Mechanism Exhibiting Good Tolerance to Oxygen and Inhibitors

A new photocatalyzed atom transfer radical polymerization (ATRP) procedure starting directly from a copper(II) bromine/phenanthroline (phen) mixture in the presence of triethylamine as a reducing agent is described. Under the irradiation of a compact blue LED lamp, the polymerization of methyl methacrylate (MMA) conducted to PMMAs with narrow molecular weights distributions (Mw/Mn ∼ 1.10). The good chain end fidelity of the products was validated in subsequent chain-extension experiments, using them as macroinitiators, either by conventional thermal ATRP or by photocatalyzed ATRP. The efficient reinitiation under light irradiation was also evidenced by a “light ON/OFF” experiment. The respective effects of several parameters on the polymerization kinetics were studied, including light intensity, the nature of the solvent, the molar ratio of the ligand, and the nature of the counterion. Besides the essential generation of the excited species [Cu(phen)2]+*, which will undergo an oxidative quenching as the k...