Hydrodynamic and electrokinetic effects on the dynamics of charged colloids and macromolecules

Abstract

We explore dynamic processes in suspensions of charge-stabilized colloidal particles and biological macromolecules. Various short-time transport properties including diffusion functions and the high-frequency viscosity, have been calculated by means of a recently developed accelerated Stokesian dynamics simulation tool. This has allowed us to study dense suspensions with many-body hydrodynamic interactions. The results of this study are used to explore the validity of generalized Stokes–Einstein relations, and the possibility of measuring self-diffusion at a finite scattering wavenumber. The influence of the electrolyte ion dynamics on the colloidal long-time self-diffusion in non-dilute suspensions of small colloids is determined using a many-component mode-coupling theory that accounts for the inter-ionic hydrodynamic interactions. We investigate the influence of the asymmetry in the electrolyte ion charges and mobilities on the friction experienced by the charged colloids. It is shown that these asymmetries affect the electrolyte friction significantly, and that the electrolyte friction contribution to self-diffusion decreases with increasing colloid concentration.