Brownian diffusivities of interacting colloidal particles measured by dynamic light scattering

Abstract

In a system of interacting colloidal particles one can distinguish collective diffusion, short-time and long-time self-diffusion and exchange diffusion. The meanings of and connections between these diffusivities are established. It is shown how these various Brownian diffusivities may be obtained from dynamic light scattering measurements on monodisperse and polydisperse systems. Experimental results for both dilute and concentrated sterically stabilized silica dispersions are presented. The experimental concentration dependence of the various diffusivities is compared with theoretical predictions.