Laboratoire de Physique Théorique
Toulouse - UMR 5152

Self-assembly of stably trapped colloidal particles at electrolyte interfaces has attracted much interest in recent years. For charge stabilized colloids at the interface, the attractive part of the interaction is dominated by strong van der Waals force which is balanced by a repulsive part coming from the electrostatic repulsion between the colloids. For large separations between the particles, this repulsive part of the interaction can be compared to a dipole-dipole interaction. However for distances close to the particle this simple dipolar picture cannot be applied. In this contribution we will focus on this limiting case (of small inter-particle distance compared to the size of the particles) by using an appropriate model. After a brief discussion of the exact analytic solutions for the electrostatic potential as well as for the surface and line interaction energies under the linearized Poisson-Boltzmann (PB) theory [1], we will introduce non-linearity in the PB theory. Our numerical data shows strong quantitative as well as qualitative changes in the surface and line interaction energies at short separation distances [2]. Moreover, a dependence of the line interaction energy on the solvation properties of the two media is observed which is overlooked by the linear theory. Our results contribute to an improved description of the interaction between colloidal particles trapped at fluid interfaces.

[1] A. Majee, M. Bier, and S. Dietrich, J. Chem. Phys. 140, 164906 (2014).

[2] A. Majee, M. Bier, and S. Dietrich, J. Chem. Phys. 145, 064707 (2016).