Addition of the 1-cyano-1-methylethyl radical to α-methylstyrene

1-Cyano-1-methylethyl end-groups in copolymers of α-methylstyrene (MST) with methyl methacrylate (MMA) and with styrene (STY) have been examined by ¹³C NMR; the end-groups have been derived from initiators suitably enriched with carbon-13. It has been shown that at 60°C MST closely resembles STY in reactivity towards the 1-cyano-1-methylethyl radical. MST is 1,89 times as reactive as MMA towards the radical at 40°C; the corresponding factors at 60 and 100°C are 1,69 and 1,55, respectively. There is no evidence for reversibility in the reaction of MST with the 1-cyano-1-methylethyl radical.