Structure and reactivities of alkyl vinyl ketones in their radical copolymerizations with styrene

Abstract To clarify the effect of the alkyl substituents in alkyl vinyl ketones (RVK) on their radical copolymerizations, the copolymerizations of six such alkyl vinyl ketones with styrene were investigated. From the results obtained, the relative reactivities of RVK toward the polystyryl radical were correlated with the Taft equation: log (1/r1) = ρ*σ* + δEs, in which σ* and Es are polar and steric substituent constants, respectively, and ρ* and δ are reaction constants. The values of ρ* and δ obtained were 0.40 ± 0.05 and 0, respectively. It was observed that the Q and e values obtained for RVK increased with increasing of σ* values, and that both relative reactivities and Q,e values of methyl vinyl ketone also increased with increasing of the ET values of the solvents used. From the spectral determination of the RVK monomers, it was also found that their n–π interactions were related to the copolymerization reactivities. Furthermore, the radical polymerization of tert‐butyl vinyl ketone (t‐BVK) with azobisisobutyronitrile (AIBN) was investigated, and its rate Rp was found to be expressed by the following rate equation: Rp = k [AIBN]0.5[t‐BVK]1.0.