Polymerization and copolymerization of α‐alkylacrylic acids and characterization of their polymers

Abstract

Abstract α‐Alkylacrylic acids (RAA's) bearing n ‐alkyl groups were found to homopolymerize with slower rates than acrylic and methacrylic acids to number‐average molecular, weight ( M̄ n ) of 10 4 or above. When the α‐substituent was a branched alkyl group, the polymerization rate and M̄ n decreased further. Reactivities of RAA's in copolymerization were interpreted by steric and resonance effects of the alkyl group using Hancock's steric substituent constant. Comparison of the reactivities of RAA's with those of methyl α‐alkylacrylates revealed that replacement with the smaller carboxyl group facilitates polymerization and copolymerization. Preference of co‐syndiotactic propagation in the copolymerization of methacrylic acid with styrene changed to random fashion in the copolymerization of the α‐higher alkyl derivatives. After methylation with diazomethane, the homopolymers were shown to be thermally less stable than poly(methyl methacrylate). T g 's of poly(methyl α‐ethylacrylate) and poly(methyl α‐ n ‐propylacrylate) were 57 and 25°C, respectively.