Copolyesteramides, 9 . Random 6‐iminohexanoyl/12‐oxydodecanoyl copolyesteramides

Random copolyesteramides composed of NH(CH 2 ) 5 CO (6A) and O(CH 2 ) 11 CO (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(CH 2 ) 5 CO/NH(CH 2 ) 11 CO 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 13 C 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 (CH 2 ) 11 units of the ester component. Some properties, including the unit cell parameters, of the little‐known 12E polyester, [poly(12‐oxydodecanoyl)], are reported.