MICROSTRUCTURE OF ACRYLAMIDE ACRYLIC-ACID COPOLYMERS .2. AS OBTAINED BY DIRECT COPOLYMERIZATION

Two series of acrylamide-acrylic acid radical copolymers obtained to high conversion respectively at low and high pH were investigated by **1**3C nuclear magnetic resonance spectroscopy. The main conclusions may be summarized as follows: (a) All copolymers are nearly atactic ( sigma //M//M approximately equals sigma //A//A approximately equals sigma approximately equals 0. 5). (b) Compositional heterogeneity leads to quasi-Bernoullian distribution of acrylamide and acrylate units in spite of non-ideal reactivity ratios. (c) The presence in the copolymerization solution of Lewis acids such as ZnCl//2 or SnCl//4 does not afford alternating copolymer as claimed by W. R. Cabaness et al.