MOLECULAR-WEIGHT DISTRIBUTION OF POLYAMIDES OBTAINED IN ANIONIC-POLYMERIZATION OF METHYL-SUBSTITUTED BETA-LACTAMS AND AMINOLYSIS OF THEIR N-BENZOYL LACTAMS

The anionic ring-opening polymerization of 3-methyl-2-azetidinone (3) in a mixture of N,N-dimethylacetamide with lithium chloride proceeded quantitatively in a homogeneous phase at 25 degrees C, as well as the living anionic polymerization of 3,3-dimethyl-, 4,4-dimethyl-2-azetidi none (1 and 2, respectively) in a similar condition. However, the mole cular weight dispersion of the polyamide obtained from 3 was found to be higher than that obtained from 1 and 2. The aminolysis reaction of their N-benzoyllactams and N-acyllactams corresponding to their growin g species with benzylamine was investigated kinetically, and one of th e reasons for broadening of the molecular weight distribution of the p olyamide obtained in the anionic polymerization of 3 was speculated to result from a low value of the ratio of the initiation reaction const ant to the propagation one. (C) 1997 John Wiley & Sons, Inc.