Distribution of monomer units in products of homogeneous irreversible copolycondensation

• Published in: Polymer science USSR 1973, Vol.15 (9), p.2424-2439
• Main Author: Kuchanov, S.I.
• Format: Article
• Language: English
• ISSN: 0032-3950; 1878-268X
• DOI: 10.1016/0032-3950(73)90115-9

The study is concerned with the solution of two main theoretical problems of homogeneous irreversible copolycondensation: finding the composition of the copolymer and explaining the type of distribution of monomer units along the chains. A general method is proposed for calculating the distribution of products of copolycondensation according to dimension and composition, to determine the composition of copolymer fractions of any molecular weight at any stage of the process. To derive a quantitative approach to the second problem the concept of the “coefficient of microheterogeneity” was introduced, which is a numerical characteristics of the degree of ordering in the distribution of units inside copolymer molecules. To carry out inter-bipolycondensation (condensation of two monomers not interacting with each other with a third so-called inter-component) a detailed study was made of the effect of various process parameters on the type of distribution of monomer units. It was shown that if the inter-component has independent functional groups, the distribution of units with arbitrary conversion, monomer ratio and activity, will be random. A general agreement was established between the type of variation of the activity of reaction centres in the inter-component and the type of distribution of units in the copolymer. If the second groups of the inter-component, in particular, have (compared with the first group) reduced reactivity, the monomer units tend to alternate; otherwise, a tendency to unit formation is observed. It was found that for the same inter-component the ordering in the distribution of units increases with an increase in the difference in activities of comonomers.