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Twenty low-conversion statistical copolymers of styrene and 2-methoxyethyl methacrylate with various composition were prepared. The dependence of the copolymer composition, molecular weight, initiation efficiency and other parameters on the composition of the monomer mixture is discussed. Kinetic data are correlated by means of various models of the copolymerization kinetics. The best fit with experimental data is provided by a diffusion-controlled termination model, especially its dyad variant suggested in this study.

Possibilities offered by classical precipitation fractionation in the preparative separation of polymer admixtures from block copolymers and in an estimate of the polydispersity in molar mass and of the heterogeneity in chemical composition of block copolymers have been examined. A mixture of a two-block copolymer, polystyrene-block-polyisoprene, with polystyrene was separated in the systems cyclohexane/1-propanol and 1,4-dioxan/1-propanol, and a mixture of three two-block styrene-isoprene copolymers having different chemical composition was fractionated in the system benzene/methanol. In the cyclohexane/1-propanol system, two commercial samples of three-block copolymers polystyrene-block-poly(ethene-co-butene)-block-polystyrene and their mixture were fractionated. The results showed that the polydispersity and chemical heterogeneity thus estimated are much lower than the real ones, especially due to the colloid properties of block copolymers.