Ordering of Attractive Colloids near a Planar Wall: Theory and Simulation

Andrej Lajovic, Matija Tomšič and Andrej Jamnik*

University of Ljubljana, Faculty of Chemistry and Chemical Technology, Aškerčeva 5, SI-1001 Ljubljana, Slovenia
* Corresponding author: E-mail: andrej.jamnik@fkkt.uni-lj.si

Abstract
Structural properties of asymmetric binary sticky hard-sphere (SHS) mixture (the particular components being denoted by SHS1 and SHS2), mimicking a system of interacting spherical colloidal particles in suspensions, near a planar wall, maintaining the equilibrium with the homogeneous (bulk) phase, are investigated. The wall-SHS1 and wall-SHS2 correlations of the SHS mixture are studied using the grand canonical Monte Carlo simulation and Percus-Yevick/Ornstein- Zernike integral equation. The density profiles of particular components show interesting shapes stemming from the interplay between the steric effects and the competitive adhesion among all possible species pairs, a characteristic feature being the discontinuities in the shapes of the profiles at the distances from the wall-SHS1 and wall-SHS2 contact planes, which correspond to different sums of the multiples of particular hard core diameters. The agreement between the theoretical predictions and simulation data is fair to very good and is better for the component comprised of weakly attractive (adhesive) particles.

Keywords: Colloidal mixture, adhesive hard sphere model, inhomogeneous systems, Percus-Yevick theory, Monte Carlo simulation