CuBr2/Me6TREN-mediated living radical polymerization of methyl methacrylate at ambient temperature

A universal nitrogen based ligand, tris2-(dimethylamino) ethyl] amine (Me₆TREN), was firstly employed as both reducing agent and ligand for atom transfer radical polymerization with activators regenerated by electron transfer (ARGET ATRP) of methyl methacrylate (MMA) in bulk and solution, using CuBr₂ as the catalyst and 2-bromoisobutyrate as the initiator. Remarkably high activity catalytic system (CuBr₂/Me₆TREN) enabled the ambient temperature polymerization and thus biradical termination reactions were low. The polymerization exhibited typical living radical polymerization features, including pseudo first-order kinetics of polymerization, linear increase in the molecular weight versus monomer conversion, and low polydispersity index values. Moreover, effects of solvent and reaction temperature on the polymerization were investigated in detail. The rate of polymerization increased with reaction temperature and the apparent activation energy of the polymerization was calculated to be 51.11 kJ/mol. Gel permeation chromatography and ¹H NMR analyses as well as chain extension experiment confirmed the living chain-end functionality.