Free planar isotropic-nematic interfaces in binary hard-rod fluids

TL;DR

This study uses Onsager theory to analyze free planar isotropic-nematic interfaces in binary hard-rod mixtures, revealing complete wetting phenomena near the triple point and significant surface tension variations due to fractionation.

Contribution

It provides the first detailed theoretical analysis of isotropic-nematic interfaces in binary hard-rod mixtures, highlighting wetting behavior and surface tension effects near the triple point.

Findings

Complete wetting of the $IN_2$ interface by an $N_1$ film near the triple point

Surface tension increases with fractionation, similar to polydisperse systems

Identification of phase coexistence and triple point in binary mixtures

Abstract

Within the Onsager theory we study free planar isotropic-nematic interfaces in binary mixtures of hard rods. For sufficiently different particle shapes the bulk phase diagrams of these mixtures exhibit a triple point, where an isotropic (I) phase coexists with two nematic phases ($N_1$ and $N_2$) of different composition. For all explored mixtures we find that upon approach of the triple point the $IN_2$ interface shows complete wetting by an intervening $N_1$ film. We compute the surface tensions of isotropic-nematic interfaces, and find a remarkable increase with fractionation, similar to the effect in polydisperse hard-rod fluids.