Studies of poly(ortho-acylstyrenes). I. Syntheses and characterization

The syntheses of a number of o-acylstyrenes (o-acetyl through o-hexanoyl) have been described. Polymerizations were carried out radically at 80°C under high vacuum. While all polymerizations conform to the usual free radical kinetic scheme, rates are sensitive to the nature of the acyl substituent, and this has been ascribed to steric effects, the bulky substituents adjacent to the propagating radicals inhibiting the approach of monomer. Molecular weight and polydispersity data indicate that both combination and disproportionation occur during terminations. UV spectra consist of two absorptions associated with n → π^* and π → π^* transitions. ¹³C-NMR spectra have been analyzed and assignments made on the basis of spectral editing. The considerable variation of glass transition temperatures has been accounted for in terms of a combination of steric and dipolar interactions.