Self-organisation of semi-flexible rod-like particles

TL;DR

This study uses computer simulations to explore how semi-flexible rod-like particles organize into various liquid-crystal phases, revealing how flexibility and aspect ratio influence phase transitions and layer spacing.

Contribution

It provides new insights into the phase behavior of semi-flexible rods, detailing how flexibility and aspect ratio affect phase transitions and layer spacing in liquid crystals.

Findings

Phase transitions shift with flexibility and aspect ratio.

Layer spacing varies with concentration and phase.

Layer spacing increases at the smectic A to B transition.

Abstract

We report on a comprehensive computer simulation study of the liquid-crystal phase behaviour of purely repulsive, semi-flexible rod-like particles. For the four aspect ratios we consider, the particles form five distinct phases depending on their packing fraction and bending flexibility: the isotropic, nematic, smectic A, smectic B and crystal phase. Upon increasing the particle bending flexibility, the various phase transitions shift to larger packing fractions. Increasing the aspect ratio achieves the opposite effect. We find two different ways how the layer spacing of the particles in the smectic A phase may respond to an increase in concentration. The layer spacing may either decrease or increase depending on the aspect ratio and flexibility. For the smectic B and the crystalline phases, increasing the concentration always decreases the layer spacing. We find that the layer spacing jumps to a larger value on transitioning from the smectic A to the smectic B phase.