Phase diagram of hard colloidal platelets: a theoretical account

TL;DR

This paper develops a comprehensive theoretical phase diagram for hard colloidal platelets, revealing the universal nature of the nematic-columnar transition and aligning qualitatively with simulation data.

Contribution

It introduces a theoretical framework combining Onsager's theory and the Parsons-Lee approximation to predict phase behavior of hard plate-like particles.

Findings

Nematic-columnar transition is universal and shape-independent.

Predicted phase diagram agrees qualitatively with simulations.

Solid (columnar) phase stability modeled with a Lennard-Jones-Devonshire equation.

Abstract

We construct the complete liquid crystal phase diagram of hard plate-like cylinders for variable aspect ratio using Onsager's second virial theory with the Parsons-Lee decoupling approximation to account for higher-body interactions in the isotropic and nematic fluid phases. The stability of the solid (columnar) state at high packing fraction is included by invoking a simple equation of state based on a Lennard-Jones-Devonshire (LJD) cell model which has proven to be quantitatively reliable over a large range of packing fractions. By employing an asymptotic analysis based on the Gaussian approximation we are able to show that the nematic-columnar transition is universal and independent of particle shape. The predicted phase diagram is in qualitative agreement with simulation results.