Head‐to‐head vinyl polymers. III. Preparation and characterization of head‐to‐head poly(acrylic acid) and its esters

Head‐to‐head (h‐h) poly(acrylic acid) (PAA) and some h‐h poly(alkyl acrylates) (PRA) with methyl, ethyl, n‐propyl, n‐butyl, isobutyl and 2‐ethylhexyl substituents were prepared by hydrolysis or esterifications of the alternating copolymer of ethylene with maleic anhydride. In general, these esterification reactions became increasingly difficult as the carbon chain in the alcohols lengthened or branched. The softening, glass transition, and degradation temperatures of the h‐h polymers obtained were somewhat higher than those of the corresponding head‐to‐tail (h‐t) polymers. The main degradation products of both h‐h and h‐t PRA were identified by pyrolytic gas chromatography as the alcohol and monomer. In addition, the relative ratios of the amounts of alcohol to monomer were larger for h‐h than for the corresponding h‐t polymers.