Surface phase transitions in polydisperse hard rod fluids

TL;DR

This paper investigates how length polydispersity affects surface phase transitions and segregation phenomena in hard rod fluids near a wall, extending classical thermodynamics to polydisperse systems.

Contribution

It extends the interface Gibbs-Duhem equation to polydisperse systems and analyzes surface phase diagrams for different length distributions.

Findings

Polydispersity influences surface tension and phase behavior.

Two distinct surface phase diagrams are identified based on length distribution decay.

Segregation and capillary nematization depend on polydispersity levels.

Abstract

I study the effect of length polydispersity in the surface phase diagram of hard rods interacting with a hard wall. The properly extended interface Gibbs-Duhem equation for a polydisperse system allows us to predict the behaviour of the surface tension as a function of the bulk density at the the wall-isotropic interface. Two groups of qualitative different bulk and surface phase diagrams are calculated from two families of parametrized length distribution functions $p(l)$. This parameterization controls the law of decay at large $l$. I also study the segregation due to polydispersity at the isotropic-nematic interface and the capillary nematization phenomena as a function of polydispersity.