SMALL-ANGLE X-RAY-ANALYSIS OF LATEX-PARTICLES USING CONTRAST VARIATION

A study of a core-shell latex consisting of a polystyrene core and a p olymethylmethacrylate (PMMA) shell by small-angle x-ray scattering is presented. Since the electron density, i.e., the contrast of both poly mers, can be easily matched by addition of sucrose to the dispersing a gent water, the internal structure of the particles can be studied by contrast variation. The scattering intensities obtained at different c ontrast are all compatible with a concentric core-shell model which ex hibits a finite nonuniformity of the thickness of the shell. The prese nt analysis furthermore reveals that the interfacial region between th e polystyrene and the PMMA phase must be very small.