Effect of [PMDETA]/[Cu(I)] Ratio, Monomer, Solvent, Counterion, Ligand, and Alkyl Bromide on the Activation Rate Constants in Atom Transfer Radical Polymerization

Abstract

A detailed study on the effect of [PMDETA]/[Cu(I)] ratio, monomer, solvent polarity, counterion, ligand, and alkyl bromide on the activation rate constant (kact) in ATRP was carried out. The highest values of kact for Cu(I)Br were obtained at [PMDETA]/[Cu(I)Br] ∼ 1/1 in more polar solvents and ascribed to a neutral [Cu(PMDETA)Br] structure of the complex. However, in less polar solvent mixtures a relatively fast reaction was observed already at the 0.5/1 ratio with the smaller rate increase up to [PMDETA]/[Cu(I)Br] ∼ 1/1. The highest values of kact for Cu(I)PF6 were observed at [PMDETA]/[Cu(I)Br] ∼ 1/1 in more polar, less polar solvent mixtures and monomer, which was explained by the formation of an ionic [Cu(PMDETA)]+PF6- complex. In both more polar and less polar media, the values of kact were slightely larger for PF6- than Br- counterion. However, in methyl acrylate, kact was 1.9 times larger for Br- than PF6- counterion. This was attributed to monomer coordination through the open coordination site of...