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. 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-eo-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-eo-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 lm 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.KEY WORDS Copolymer Sequence Distribution I DL Type Conformational Sequence I Poly(acrylonitrile-co-methacrylonitrilc) I 13 C NMR Spectrometer I Bernoulli Statistics I Markov Statistics I Triad Sequence I Sequence distribution combined with stereoregularity of homo-and copolymeric chains, which is determined by polymerization mechanism, is a very important factor in governing the dissolved state of the polymers in solution, the solution properties, the structure and properties of the polymer solid. The most powerful experimental tool to determine the sequence distribution is nuclear magnetic resonance (NMR). But NMR often gives information on the diad-base sequence distribution of many polymers, that is meso or racemo (m or r) conformation for homo-and copolymers. The mr expression might be adequate to describe the sequence distribution combined with stereoregularity if the direction of the sequence of molecular chain for the homo-or copolymer in question can be completely neglected. Lots of studies on sequence distribution of homo-and copolymers based on the mr expression have been reported from the early works made by Frisch et al. 1 and Bovey. 2 The m or r diad sequence, however, essentially arises from the result of reaction of monomers with their chirality, D or Lin the polymerization process. For example, an r diad includes a DL or LD sequence, and if the direction of the sequence cannot be ignored DL and LD diads should be distinguished. Consequently, NMR data on the sequence distribution had better to be analyzed using a statistical model descri...