A series of phosphorus-containing ligands was employed to establish a novel polymerization system for the iron(III)-mediated polymerization of methyl methacrylate (MMA) just using FeCl3·6H2O or FeBr3 as the catalyst without any additional initiators and reducing agents. The polymerization results showed that this polymerization system involving MMA/FeX3 (X = Cl, Br)/phosphorus-containing ligand was a typical “living”/controlled radical polymerization process: first-order polymerization kinetics with respect to monomer concentration and a linear increase of the molecular weight of the resultant PMMAs with conversion while keeping a narrow molecular weight distribution. Chain end analysis of the obtained PMMA based on 1H NMR, 31P NMR were used to confirm the precise structure of the obtained polymers. The results showed that phosphorus-containing complexes acted as both ligand and thermal radical initiators in this process, which was consistent with a reverse atom transfer radical polymerization (reverse ATRP) mechanism.
