Model calculations of the distribution function of molecular weight and chemical composition of binary statistical copolymers

Model calculations based on the kinetics of free-radical copolymerization were carried out for the distribution functions of molecular weight and chemical composition, and for heterogeneity parameters of statistical copolymers. The calculations were conducted so as to depict the dependence of the heterogeneity parameters on the degree of conversion and to make possible an estimate of the maximal heterogeneity of statistical copolymers at given monomer reactivity ratios and rate constants. A comparison of the results obtained with a critical analysis of the feasibility of the determination of heterogeneity parameters by light scattering has revealed that, for statistical co polymers, this method can in principle be used with satisfactory accuracy only with samples of high degree of conversion and high molecular weight. The frequently used approximation P = 0 cannot be applied with out careful verification.