COPOLYESTERAMIDES .8. A COMPARISON OF SUBSTANTIALLY ALTERNATING 12-OXYDODECANOYL/OMEGA-IMINOALKANOYL POLYESTERAMIDES WITH EQUIVALENT RANDOM COPOLYMERS

The polycondensation of methyl N-(12-hydroxydodecanoyl)-omega-aminoalkanoates (HO(CH2)11CONH(CH2)xCOOCH3) has been studied as a source of the alternating polyesteramides [O(CH2)11CONH(CH2)xCO]n, and the properties of the products compared with those of equivalent random copolymers of similar co-unit ratio. Polymerization of the esters with x = 10 and 11 occurred straight-forwardly, giving crystalline products which were distinguishable from the random counterparts by DSC but not by 67 MHz C-13 NMR. For x = 5 the reaction was complicated by progressive partial elimination of the amide moiety as 6-hexanolactam and by transamidation leading, for the polymer of highest amide content obtained, to an imperfect structure with ca. 76% of the sub-units in alternating arrangement, the remainder being composed of oligoester and diamide units. This deviation from ideality has been elucidated by a study of the C-13 NMR spectra of a wide range of model compounds which has yielded criteria for the recognition of oligomeric iminohexanoyl units, and by the NMR and MS examination of the products of aminolytic degradation. The results explain the multiple signals found in the C-13 NMR spectra of the imperfectly alternating polymer (x = 5) and of its random analogues.