Aliphatic-aromatic polyamide-imides from diisocyanates, 1. 1H and 13C NMR study of polymer structure

The reaction of a diisocyanate and an asymmetric aliphatic-aromatic diacid containing a preformed imide group was studied in order to obtain polyamide-imides. It is shown in this paper that combined ¹H and ¹³C NMR spectrometry will permit the quantitative evaluation of the proportions of head-tail, head-head, tail-tail additions, provided the content of urea in the polymer is low. In order to obtain unequivocal assignments and to thoroughly characterize the NMR spectra of the polymer, several model compounds resembling the polymer backbone were synthesized. A model polymer was synthesized with the same purpose, and its ¹H and ¹³C NMR spectra fully assigned. Unexpected chemical functions in the polymer, like urea and carboxylic acid, can also be easily detected and quantified by NMR.