Copolymerization Reactivities of α-Substituted Crotonyl Monomers

The radical copolymerizations of various α- substituted crotonyl monomers with styrene (St) and acrylonitrile (AN) were investigated, and the copolymerization parameters were determined by a least-squares procedure reported previously. The relative reactivities of the α-substituted crotonyl monomers toward polymer radicals of St and AN were found to correlate with the equation: log (relative reactivity of CH₃CHdbnd]CXY) = ρ (σ + σ_Y) + A(Δlog Q_x + Δlog Q_Y), where Σ and Δlog Q are the polar Hammett and resonance substituent constants, respectively, and p and A are reaction constants. From the observed straight line relationships, the values of p and A were obtained to be as follows: ρ = 0.66, A = 0.75 for attack of poly-St radical, and ρ = -3.20, A = 1.3 for attack of poly-AN radical.