Resonance, polar, and steric effects of substituent on monomer reactivity in radical polymerization of alkyl 4‐vinylbenzoate and butylacrylate

Resonance, polar, and steric effects play a major role in determining monomer reactivity in free‐radical polymerization. We copolymerized butylacrylate (M1) with styrene and a series of alkyl esters of 4‐vinylbenzoic acid (AVB, M2) by conventional and atom transfer radical polymerization. The alkyl chain of an ester group was varied as butyl, octyl, dodecyl, octadecyl, and docosyl. The reactivity of the AVB monomer having a butyl ester chain at the para position was much higher than styrene in this copolymerization, but with increasing chain length the reactivity of the AVB monomer gradually decreased. These results suggested that when resonance and the polar effect are kept nearly constant, the steric effect becomes predominant in determining the reactivity of a monomer. The monomer reactivity is not affected to a great extent by changes in the initiator system or reaction conditions.