SAXS STUDY OF OMEGA-METAL AND ALPHA,OMEGA-METAL SULFONATO POLYSTYRENES IN TOLUENE SOLUTION

Solutions of omega- and alpha,omega-barium sulfonato polystyrenes in t oluene have been investigated by SAXS as a function of concentration. A characteristic ionic peak is displayed over the whole investigated c oncentration range. The experimental data are in favor of the ion pair aggregation into small stable multiplets homogeneously distributed th roughout the material. The characteristic distance is related to the a verage intermultiplet distance d. A general law has been derived for t he dependence of d on molecular weight, functionality, and concentrati on of the polymer. The size of the multiplets does not depend signific antly on polymer concentration and molecular weight. Below a critical concentration which depends on the chain length, solutions of difuncti onal samples display a constant average intermultiplet distance. This behavior has been attributed to the partial multiplet dissociation by the fully extended chains. Sample preparation and subsequent thermal t reatment have no influence on the position of the ionic peak but can a ffect the intensity of the peak and the upturn in scattered intensity at very small angles.