POLYMERIZATION AND COPOLYMERIZATION OF ALPHA-ALKYLACRYLIC ACIDS AND CHARACTERIZATION OF THEIR POLYMERS

alpha-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 (M(n)BAR) of 10(4) or above. When the alpha-substituent was a branched alkyl group, the polymerization rate and M(n)BAR 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 alpha-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 alpha-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 alpha-ethylacrylate) and poly (methyl alpha-n-propylacrylate) were 57 and 25-degrees-C, respectively.