Ordered droplet structures at the liquid crystal surface and elastic-capillary colloidal interactions

TL;DR

This paper investigates how colloidal droplets at a liquid crystal surface form ordered structures due to elastic-capillary interactions, revealing new surface-driven assembly mechanisms distinct from bulk behaviors.

Contribution

It introduces the concept of elastic-capillary coupling at liquid crystal surfaces, demonstrating its role in forming ordered colloidal patterns at micron scales.

Findings

Formation of hexagonal and chain structures of droplets

Elastic-capillary interactions dominate over buoyancy effects at micron scales

Surface-induced distortions lead to strong capillary attractions

Abstract

We demonstrate a variety of ordered patterns, including hexagonal structures and chains, formed by colloidal particles (droplets) at the free surface of a nematic liquid crystal (LC). The surface placement introduces a new type of particle interaction as compared to particles entirely in the LC bulk. Namely, director deformations caused by the particle lead to distortions of the interface and thus to capillary attraction. The elastic-capillary coupling is strong enough to remain relevant even at the micron scale when its buoyancy-capillary counterpart becomes irrelevant.