Copolyesteramides, 9^†. Random 6-iminohexanoyl/12-oxydodecanoyl copolyesteramides

Random copolyesteramides composed of NH(CH₂)₅CO (6A) and O(CH₂)₁₁CO (12E) units were prepared by co-polymerization/condensation of 6-hexanolactam with 12-hydroxydodecanoic acid. Lactam elimination during the reactions limited the attainable 6A content to ca. 70 mol-%. The properties of the materials differ markedly from those of the isomeric O(CH₂)₅CO/NH(CH₂)₁₁CO random copolymers. Those with up to 20 mol-% 6A units are crystalline and essentially modified 12E polymers. Thereafter, up to ca. 55 mol-% 6A, the materials were of an intermediate, relatively homogeneous phase character, a discrete polyamide phase appearing incipiently only at still higher 6A contents. The random nature of the copolymers was confirmed by ¹³C NMR spectroscopy, and IR examination showed the prevalence of amide-ester hydrogen bonding at lower 6A contents together with a degree of intramolecular sub-crystalline order in the 12E component over the range from 20–60 mol-% 6A. It is suggested that the copolymer texture in this range is largely controlled by the preferred conformation of the (CH₂)₁₁ units of the ester component. Some properties, including the unit cell parameters, of the little-known 12E polyester, [poly(12-oxydodecanoyl)], are reported.