Competition of Lattice and Basis for Alignment of Nematic Liquid Crystals

TL;DR

This paper investigates how the competition between lattice and motif shapes influences the alignment of nematic liquid crystals, revealing tunable orientation control through patterning and motif shape adjustments.

Contribution

It introduces a method to control nematic liquid crystal alignment by tuning lattice and motif geometries, including elliptical motifs for arbitrary orientation control.

Findings

Orientation transition depends on coverage fraction for circular motifs

Elliptical motifs enable arbitrary alignment direction control

Tunable anchoring energy through motif shape and lattice patterning

Abstract

Due to elastic anisotropy, two-dimensional patterning of substrates can promote weak azimuthal alignment of adjacent nematic liquid crystals. Here, we consider how such alignment can be achieved using a periodic square lattice of circular or elliptical motifs. In particular, we examine ways in which the lattice and motif can compete to favor differing orientations. Using Monte Carlo simulation and continuum elasticity we find, for circular motifs, an orientational transition depending on the coverage fraction. If the circles are generalised to ellipses, arbitrary control of the effective alignment direction and anchoring energy becomes achievable by appropriate tuning of the ellipse motif relative to the periodic lattice patterning. This has possible applications in both monostable and bi-stable liquid crystal device contexts.