Effects of salts of metals on vinyl polymerization. Part 4.—Polymerization of styrene in presence of cupric chloride

Abstract

The AIBN-initiated polymerization of styrene in the presence of cupric chloride and 20% by volume DMF has been studied at 50, 60 and 70°C. The salt behaves as an ideal inhibitor, i.e., the post-inhibition rate is not significantly different from the rate obtained in the absence of inhibitor. The rate constants for the decomposition of AIBN into “accessible” free radicals, obtained from plots of inhibition period against cupric chloride concentration are 2.22 × 10^–6, 1.04 × 10^–5, 6.0 × 10^–4 sec^–1 at 50, 60 and 70°C respectively. The Arrhenius activation energy based on these data is 36.5±2 kcal mole^–1. From a study of the acceleration period following inhibition the ratio k_x/k_p, where k_x is the rate constant for the reaction between polystyryl radicals and the cupric salt, has been evaluated at each of the temperatures quoted. The value of k_x thus obtained at 60°C is 1.81 × 10⁶ 1. mole^–1 sec^–1, which is an order of magnitude greater than that for the corresponding reaction with ferric chloride in DMF.