Micellization in water of two homologous series of AB-type diblock copolymers, composed of polystyrene (PS) as the A block and poly(ethy1ene oxide) (PEO) as the B block, were investigated by small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). The copolymers have molecular weights &, in the range 2000-34800, and have in a given series, the same number of repeating units of the PS block, (Nps = 10 and 38), and a variable number of repeating units of the PEO block (NpEo values in the range 23-704).In order to avoid secondary association of micelles, a dialysis technique was used to prepare the micellar systems, in the case of copolymers having high I @ , , values of the PS block. The experimental micelle properties such as the core radius R, and the aggregation number N of non-equilibrium structures, so called "frozen micelles", obtained by dialysis, were found to be independent of the copolymer characteristics. However, for equilibrium structures, obtained by direct solubilization of the copolymers (Nps = 10) in water, R, and N were found to decrease with increasing NpEo for the homologous series.
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