The activation rate parameters of polystyrene (k S act) and poly(butyl acrylate) (k BA act) macroinitiators in ATRP catalyzed by CuBr/4,4‘-di-n-heptyl-2,2‘-bipyridine have been determined at 110 °C using a combination of nitroxide exchange reactions with HPLC analysis. The method is based on exchange of the bromide end group with a hydroxy-TEMPO end group. The depletion of the macroinitiator is monitored as a function of time. The method is applicable in different solvents, which implies the possibility to investigate the effect of solvent characteristics. Solvent polarity has a negative influence on k S act and a positive effect on k BA act. The ability of the solvent to act as ligand in the copper complex hampers the activation process for both macroinitiators, while the presence of hydroxy groups in the solvent increases both activation rate parameters.

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The rate constants of deactivation in atom transfer radical polymerization of styrene and butyl acrylate have been determined. The values are k deact = 7 × 107 L mol-1 s-1 for styrene and 1 × 108 L mol-1 s-1 for butyl acrylate, both measured in p-xylene at 110 °C. The effect of solvent polarity seems to be insignificant on the basis of results measured in butyl acetate. The proper conditions for the experimental determination of k deact were found on the basis of computer simulations. Conditions were chosen such that the sensitivity of the measured rate constants toward experimental conditions and toward uncertainties in other rate parameters was minimal.

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