Kinetic Study of the Homogeneous Atom Transfer Radical Polymerization of Methyl Methacrylate

Abstract

The homogeneous controlled/“living” radical polymerization of methyl methacrylate (MMA) using the atom transfer radical polymerization (ATRP) with CuCl/4,4‘-di(5-nonyl)-2,2‘-bipyridine catalytic system and diphenyl ether as the solvent generated well-defined polymers with polydispersities M w / M n ≤ 1.2. The evolution of the molecular weights of the polymers follows the ratio of the mass of the consumed monomer to the initial initiator concentration. The rate of polymerization follows first-order kinetics with respect to the decrease of monomer concentration. The polymerization rate reaches a maximum when the ratio of ligand-to-Cu I Cl is one-to-one. ATRP of MMA shows first-order kinetics with respect to both Cu I Cl and the initiator, alkyl or sulfonyl chloride. The rate of polymerization did not obey simple negative first-order kinetics with respect to the concentration of Cu II Cl, partially due to a persistent radical effect, which resulted in the increase of [Cu II Cl] in the initial stage of polymerization. Thermodynamic data and activation parameters for the solution ATRP of MMA are reported.