Vapour-Liquid equilibrium and low-temperature liquid-crystal phase diagram of discotic colloids

TL;DR

This study uses Monte Carlo simulations to explore the phase diagram and vapor-liquid coexistence of discotic colloids with varying aspect ratios, revealing complex phase behaviors including novel lamellar phases.

Contribution

It provides new insights into the phase behavior of discotic colloids with different anisotropies, especially identifying a new lamellar phase at low aspect ratios.

Findings

Vapor coexistence with isotropic and columnar phases for less anisotropic particles.

Shift of vapor-liquid coexistence to lower temperatures with increasing particle anisotropy.

Discovery of a novel lamellar phase with layered particle arrangements.

Abstract

Discotic colloids give rise to a paradigmatic family of liquid crystals with sound applications in Materials Science. In this paper, Monte Carlo simulations are employed to characterize the low-temperature liquid crystal phase diagram and the vapour-liquid coexistence of discotic colloids interacting via a Kihara potential. Discoidal particles with thickness-diameter aspect ratios $L^*\equiv L/D$=\,0.5, 0.3, 0.2 and 0.1 are considered. For the less anisotropic particles ($L^*$$\ge$0.2), coexistence of a vapour phase with the isotropic fluid and with the columnar liquid crystal phase is observed. As the particle anisotropy increases, the vapour-liquid coexistence shifts to lower temperatures and its density range diminishes, eventually merging with coexistences involving the liquid crystal phases. The $L^*=$\,0.1 fluid displays a rich sequence of mesophases, including a nematic phase and a novel lamellar phase in which particles arrange in layers perpendicular to the nematic director.