Copolymer Sequence Distribution with Chiral Stereoregularity and Its Application to Poly(acrylonitrile-co-methacrylonitrile)

Abstract

An attempt was made to elucidate the general mathematical expression of the polymer sequence distribution for copolymers with two stereoregular monomer units by considering their chirality (D or L form) distribution based on Markov statistics. The equations derived (DL equations) were compared with those based on conventional meso and racemo conformation (mr equations) [K. Kamide and K. Hisatani, Polym. J., 24, 1377 (1992)]. For this purpose the literature data of NMR on sequence distribution of three kinds of poly(acrylonitrile-co-methacrylonitrile) i.e., poly(AN-co-MAN), prepared by radical polymerization using redox catalysis and anionic method using dialkylmagnesium as initiator at high and low temperature, were analyzed. DL equations were found to explain well the monomer unit sequence distribution with cotacticity of two poly(AN-co-MAN), polymerized by radical method and by anionic methods at temperatures, rather than mr equations. The reaction probability of these copolymers estimated by [Bernoulli]−[1st Markov]cor statistics where monomer unit sequence and its cotacticity obey Bernoulli and 1st order Markov processes, respectively, has revealed that racemo addition of MAN monomer does not occur in the above anionic polymerization essentially. For all of three samples, the stereoregular sequences obey 1st order Markov statistics, but monomer unit ones obey 2nd order Markov statistics for low temperature anionic method and Bernoulli for the other two method.