Bulk and wetting phenomena in a colloidal mixture of hard spheres and platelets

TL;DR

This study uses density functional theory to explore the phase behavior and wetting phenomena in a binary colloidal mixture of hard spheres and platelets, revealing liquid-liquid coexistence and a first-order wetting transition.

Contribution

It provides new insights into the wetting behavior and phase coexistence in sphere-platelet colloidal mixtures, contrasting with previous studies on similar systems.

Findings

Liquid-liquid coexistence of sphere-rich and platelet-rich phases.

Complete wetting of the sphere-rich phase at the wall near the binodal.

Absence of layering transitions unlike sphere-polymer or rod mixtures.

Abstract

Density functional theory is used to study binary colloidal fluids consisting of hard spheres and thin platelets in their bulk and near a planar hard wall. This system exhibits liquid-liquid coexistence of a phase that is rich in spheres (poor in platelets) and a phase that is poor in spheres (rich in platelets). For the mixture near a planar hard wall, we find that the phase rich in spheres wets the wall completely upon approaching the liquid demixing binodal from the sphere-poor phase, provided the concentration of the platelets is smaller than a threshold value which marks a first-order wetting transition at coexistence. No layering transitions are found in contrast to recent studies on binary mixtures of spheres and non-adsorbing polymers or thin hard rods.