Projects

Abstract: Commonly the dynamics of charged colloids in suspensions are studies using an effective one-component model in which the microionic atmosphere around the colloids plus the colloid itself is treated as a single composite object ("dressed colloid") with effective pair-interactions. In this project, we intend to study the dynamics of charged colloids, with the microionic degrees of freedom taken into account explicity. On a mean-field level, the basis for such a description of colloidal systems is given by the "electrokinetic equations" with appropriate boundary conditions at a colloid surfaces.

Our project aims at developing a numerical scheme to fully solve the electrokinectic equations in all three spatial dimensions to obtain the fluid flow and the electric potential in the vicinity of moving colloids which are suspended in an electrolyte solution and subjected to external force fields. The numerical solution of these equations will allow us to consider arbitrarily strong external fields, and thus a treatment far beyond the level of linear-response theory. We then intend to study a variety of dynamical properties of colloidal macroions in electrolyte solution, such as i) the electrophoretic mobility of a single tracer colloid for varying salt concentrations and colloidal charges, ii) the effective dynamical interaction between two (homogeneously and heterogeneously charged) colloids in strong external electric field, iii) the time-dependence of double-layer formation and relaxation processes, and iv) single-file diffusion of charged colloids.

• Klein, Rudolf - Project head

• FB Physik