Orientational orders of small anisotropic molecules confined in slit pores

TL;DR

This study uses Monte Carlo simulations to explore how small anisotropic molecules confined between two hard walls can form orientationally ordered phases, suggesting confinement promotes liquid crystal formation at smaller molecular elongations.

Contribution

It demonstrates that confinement can induce nematic phases in small anisotropic molecules, reducing the molecular elongation needed for liquid crystal formation compared to bulk.

Findings

Nematic phase is unstable in bulk for small molecules.

Confinement enables formation of orientation-ordered phases.

Small molecule liquid crystals may exist under confinement.

Abstract

We have studied phase behavior of hard gaussian overlap molecules with small anisotropic parameter confined in two plane parallel structureless hard walls. Our investigation based on standard constant-NPT Monte Carlo molecular simulation led us to some interesting findings. For small anisotropic molecules the nematic phase is instable in bulk, while, if the distance between the walls is small enough, an orientation-ordered phase can form. This result indicates that the required molecular elongation forming liquid-crystal phases is smaller in confinement than that in bulk. Considering the value of the elongation of molecules, the computed result inplies that small molecule liquid crystals may exist in confinement.