THE INTERFACE BETWEEN IMMISCIBLE POLYMERS IN COMPOSITE LATEXES - A SMALL-ANGLE X-RAY-SCATTERING STUDY EMPLOYING CONTRAST VARIATION

An investigation of the radial structure of composite latex particles by small-angle x-ray scattering (SAXS) is given. Measurements at diffe rent contrasts were done by addition of sucrose to the dispersion medi um water. The latex particles investigated here consist of a poly(styr ene) core and a shell of poly(methylmethacrylate) and were prepared by seeded emulsion polymerization. Since the electron density of both po lymers can be easily matched by concentrated sucrose solution, a full analysis of the radial electron density by contrast variation can be g iven. Depending on the mode of monomer addition during the second poly merization step a very sharp or a diffuse interface between the two in compatible polymers may result.