Synthesis of poly(ester amide)s derived from glycolic acid and the amino acids:: β-alanine or 4-aminobutyric acid

Full Paper: The polymerization of metal salts of N-chloroacetyl-beta-alanine and N-chloroacetyl-4-aminobutyric acid was investigated. The former gives a mixture of polymer and a seven-membered cyclic compound constituted of glycolic and beta-alanine units, and its reaction proceeds in the solid state. However, liquefaction is observed in the second case giving rise to a polymer with a moderate molecular weight. Condensation kinetics of both sodium and silver salts of N-chloroacetyl-beta-alanine have been studied by differential scanning calorimetry. Copolymers of glycolic acid and I beta-alanine with a molar ratio of glycolic acid/beta-alanine varying from 0.5 to 1.0 have been synthesized by thermal reaction of co-precipitated crystals of the sodium salts of chloroacetic acid and N-chloroacetyl-beta-alanine. NMR spectroscopy indicates that copolymers tend to have a random distribution. The resulting new poly(ester amide)s have been characterized by spectroscopy and thermal analysis.