Surfaces with quenched and annealed disordered charge distributions

Abstract

We consider surfaces with disordered charge distribution. The disorder can be caused by mobile charges, as for example in mixed lipid bilayers, or by weakly charged surfaces where charge regulation takes place (e.g. carboxyl groups). Using Monte-Carlo simulation methods we find for quenched as well as annealed disordered charge distributions counterion densities close to the surface that are significantly larger than for ordered regularly spaced surface ions. Our field-theoretic results agree well with results obtained from Monte-Carlo simulations of the system. Furthermore, we obtain expressions for the effective interaction between charged colloids and charged rods close to a charged surface and discuss the effect of the surface-ion mobility and polarization charges on the interaction. In general, polarization effects as well as surface-ion mobility lead to a weakening of the effective interaction between charged objects.