Effects of salts of metals on vinyl polymerization. Part 6.—Polymerization of methyl methacrylate in the presence of cupric bromide

Abstract

The polymerization of methyl methacrylate initiated with AIBN and inhibited with cupric bromide in DMF has been studied at from 40–70°C. Rate constants for the initiation reaction, obtained by the inhibition period method, were 6.2 × 10^–7, 3.7 × 10^–6, 1.42 × 10^–5 and 8 × 10^–5 s^–1 at 40, 50, 60 and 70°C respectively, yielding an activation energy of 137.5 kJ mol^–1. The acceleration period following complete inhibition was rapid and became distributed due to self-heating effects when ordinary dilatometers were used. Disc-bulb dilatometers helped to removed this distortion. Values of the ratio where k_x/k_p, where k_x is the rate constant from the reaction between polymethyl-methacrylate radicals and the cupric salts, were greater than those obtained using cupric chloride as an inhibitor.