Repulsion-attraction switching of nematic colloids formed by liquid crystal dispersions of polygonal prisms

TL;DR

This paper demonstrates how the elastic interactions between polygonal prism colloids in nematic liquid crystals can be precisely controlled and switched between repulsive and attractive by manipulating defect pinning, enabling tunable self-assembly.

Contribution

It introduces a method to control colloid interactions in nematic liquid crystals through defect pinning on polygonal prisms, revealing new ways to tune self-assembly.

Findings

Elastic interactions can be switched between repulsive and attractive.

Disclination pinning affects the symmetry of director distortions.

Controlled defect localization influences diffusion and assembly.

Abstract

Self-assembly of colloidal particles due to elastic interactions in nematic liquid crystals promises tunable composite materials and can be guided by exploiting surface functionalization, geometric shape and topology, though these means of controlling self-assembly remain limited. Here, we realize low-symmetry achiral and chiral elastic colloids in the nematic liquid crystals using colloidal polygonal concave and convex prisms. We show that the controlled pinning of disclinations at the prisms edges alters the symmetry of director distortions around the prisms and their orientation with respect to the far-field director. The controlled localization of the disclinations at the prism's edges significantly influences anisotropy of the diffusion properties of prisms dispersed in liquid crystals and allows one to modify their self-assembly. We show that elastic interactions between polygonal prisms can be switched between repulsive and attractive just by controlled re-pinning the disclinations at different edges using laser tweezers. Our findings demonstrate that elastic interactions between colloidal particles dispersed in nematic liquid crystals are sensitive to the topologically equivalent but geometrically rich controlled configurations of the particle-induced defects.