Enhancement of the Rate of Atom Transfer Radical Polymerization in Organic Solvents by Addition of Water: An Electrochemical Study.
Paola Pavan, Francesca Lorandi, Francesco De Bon, Armando Gennaro, Abdirisak Ahmed Isse
Abstract
Abstract Addition of water to organic solvents enhances the rate of atom transfer radical polymerization (ATRP). To understand the origin of this rate enhancement, the effects of H 2 O on the redox properties of [Cu II TPMA] 2+ and [BrCu II TPMA] + (TPMA=tris(2‐pyridylmethyl)amine), and on the ATRP equilibrium ( K ATRP ) and activation rate ( k act ) constants of methyl 2‐bromopropionate by [Cu I TPMA] + were investigated in CH 3 CN, DMF and DMSO and their mixtures with methyl acrylate (MA). E °s of the complexes allowed evaluation of the relative halidophilicities of [Cu II TPMA] 2+ and [Cu I TPMA] + , K II Br and K I Br , respectively. K II Br / K I Br dropped in pure solvents and solvent/MA mixtures when 11 % (v/v) H 2 O was added, suggesting that H 2 O hampers the stability of the deactivator [BrCu II TPMA] + . Conversely, both k act and K ATRP were enhanced by the presence of water. In solvent/MA mixtures (50/50, v/v), addition of 11 % (v/v) H 2 O increased K ATRP by a factor of 2–3, which could explain the accelerating effect of H 2 O on ATRP in organic solvents.