A Simplified Fe-Based PhotoATRP Using Only Monomers and Solvent

A photoinduced atom transfer radical polymerization (photoATRP) of methacrylates is investigated using air-stable FeBr₃ as catalyst in the absence of conventional ATRP initiators, additional ligands, reducing agents, and/or radical initiators. The ATRP alkyl halide initiator is formed in situ via photoreduction of FeBr₃ by methacrylate monomers. The kinetics of the polymerization display a linear semilogarithmic plot after several hours of induction period. The molecular weight can be modulated by additions of different amounts of FeBr₃ , and polymers have narrow molecular weight distributions. Thus, FeBr₃ acts as deactivator, as well as a source of activator FeBr₂ and initiator. This method features a temporal control, and can provide various polymethacrylates with high chain end functionality.