DETERMINATION OF SIZES OF SPHERICAL-PARTICLES, PREPARED BY DISPERSIONPOLYMERIZATION OF METHYL-METHACRYLATE IN NONAQUEOUS MEDIUM, BY ANALYSIS OF THE PARTICLE SCATTERING AND AUTOCORRELATION FUNCTIONS

Particle masses of the order of 10(8)-10(10) g mol-1 and the radii of gyration and hydrodynamic radii of spherical poly(methyl methacrylate) particles were characterized by combined static and dynamic light sca ttering. The dispersions were prepared by dispersion polymerization an d stabilized by polystyrene-block-poly(ethylene-co-propylene). The rad ii of gyration were calculated from the measured particle scattering i ntensity by fitting procedures using the Rayleigh formula for spheres. This practice allows the use of all points actually measured instead of the uncertain values at low angles only. The strongly disturbing in fluence of small contents of large particles (aggregated particles, du st) was eliminated. The autocorrelation functions were measured by dyn amic light scattering and analysed by the Contin procedure. The corona s and densities of the particles could be characterized on the basis o f the geometric radii of the pure main components.