Dynamic light scattering study of concentrated dispersions of anisotropic spherical colloids

Quasielastic light scattering measurements are performed on a suspension of spherical particles possessing an intrinsic optical anisotropy. The particles are prepared by emulsion polymerization of a polytetrafluoroethylene copolymer, and have a radius of 85 nm. A theoretical treatment is developed which shows that the correlation function of depolarized scattered intensity contains both the translational and rotational self-diffusion coefficients Ds and Dr. The measurements allow the derivation of the dependence of Ds and Dr on the volume fraction. The experimental data demonstrate that the rotational diffusion of a sphere is influenced by hydrodynamic interactions, in qualitative agreement with recent calculations by Jones.