Symmetry Breaking and Electrostatic Attraction between Two Identical Surfaces

Franck Plouraboué (1) , Hua Chia Chang (2)

1 IMFT - Institut de mécanique des fluides de Toulouse
2 Center for Micro-fluidics and Medical Diagnostics

By allowing the surface charge of one surface to affect the adsorption equilibrium of the other, we establish the existence of a long-range attractive interaction between two identical surfaces in an electrolyte containing polyvalent counter ions with a mean-field Poisson-Boltzmann approach. A Stern electrostatic condition from linearization of the mass-action adsorption isotherm is used to capture how polyvalent ion condensation affects and reverses the surface charge. We furthermore establish a direct mapping between this Stern layer conditions and previously derived modified Mean-field formulations associated with correlated fluctuations theory. For a sufficiently potential-sensitive isotherm, anti-symmetric charge inversion can occur to produce an attractive force that increases with decreasing ionic strengths. Analyses of a mass-action isotherm produce force-separation relations, including an exponential far-field force decay distinct but consistent with previously proposed correlated fluctuation theories, and in quantitative agreement with experimental data.

Mots clés: Poisson-Boltzmann; correlated fluctuation theory; like charge attraction

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Franck Plouraboué, Hua Chia Chang. Symmetry Breaking and Electrostatic Attraction between Two Identical Surfaces. 2008. ⟨hal-00338936⟩