Dilute solutions of styrene/butadiene/styrene (SBS) block copolymers of various compositions in selective solvent mixtures are studied by viscometry, equilibrium dialysis, differential refractometry and light scattering. The addition of ethanol as a selective precipitant to a dioxan solution of SBS leads to selective precipitation of butadiene blocks which are kept in solution by solvated styrene blocks. Under the given conditions (temperature, copolymer composition, mixed solvent composition) the forming micelles attain, at a certain copolymer concentration, a stable weight. The results of measurements show that the micelles are very small particles (radius of gyration up to 20nm) of a high weight (up to 15·106); consequently, the average volume fraction of the polymer in the space occupied by a micelle attains unusually large values (up to 0.35).
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Tuzar et al. (1972) studied this question.
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