Bulk and interfacial properties of binary hard-platelet fluids

TL;DR

This study uses density-functional theory to analyze the interfacial and bulk properties of binary mixtures of hard platelets, revealing complex behaviors like density inversion, oscillations, and wetting phenomena.

Contribution

It introduces a fundamental measure theory adapted to the Zwanzig model to investigate interfaces in binary hard-platelet fluids, highlighting novel interfacial phenomena.

Findings

Density inversion and oscillatory profiles observed

Lowest interfacial tension when platelets are parallel to interface

Complete wetting of isotropic-nematic interface by a second nematic phase

Abstract

Interfaces between demixed fluid phases of binary mixtures of hard platelets are investigated using density-functional theory. The corresponding excess free energy functional is calculated within a fundamental measure theory adapted to the Zwanzig model, in which the orientations of the particles of rectangular shape are restricted to three orthogonal orientations. Density and orientational order parameter profiles at interfaces between coexisting phases as well as the interfacial tension are determined. A density inversion, oscillatory density profiles, and a Fisher-Widom line have been found in a mixture of large thin and small thick platelets. The lowest interfacial tension corresponds to the mean bulk orientation of the platelets being parallel to the interface. For a mixture of large and small thin platelets, complete wetting of an isotropic-nematic interface by a second nematic phase is found.