Reactions of the 2-cyano-2-propyl radical with vinyl acetate and other monomers: A study of head-addition

Polymers have been prepared at 60 and 100°C using initiators giving the 2‐cyano‐2‐propyl radical enriched with carbon‐13 in the nitrile group. Examination by NMR of the (CH3)2C(CN) end groups in the resulting polymers of vinyl acetate (VAC) and of appropriate model compounds has indicated that up to 20% of these end groups correspond to the product of head‐addition of the primary radical to VAC at 60°C. Similar end groups have been found in poly(vinyl formate) but not in poly(methyl methacrylate) and polystyrene. In polyVAC prepared at 100°C, the proportion of end groups attached to the head of a monomeric unit is higher than for polymers made at 60°C.