Annihilation dynamics of topological defects induced by microparticles in nematic liquid crystals

• Published in: Soft matter Vol. 15; no. 43; pp. 8749 - 8757
• Main Authors: Shen, Yuan, Dierking, Ingo
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Anchoring; Cell size; Crystal defects; Crystals; Defects; Drag; Electric field strength; Liquid crystals; Microparticles; Nematic crystals; Topology; Viscous drag
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/c9sm01710k

The annihilation dynamics of s = ±1 topological defects with and without microparticles in a nematic liquid crystal were investigated and compared. The microparticle with a homeotropic surface anchoring can act as a s = +1 defect and produce a corresponding s = −1 defect nearby. Both of them attract and move towards each other. The speed of the positive defect induced by the microparticle is much slower than that of the negative defect, contrary to the situation without particles. The effects of electric field strength and frequency, particle size, the confining cell gap, and temperature were systematically investigated. The study shows that the dynamics of the annihilation process is related to a complex interplay between elastic attractions, viscous drag forces, backflow effects, director configurations and cell confinement. The annihilation dynamics of liquid crystal topological defects with micro-particles is governed by a complex interplay between elastic attraction, backflow, viscous drag forces, confinement and applied electric field conditions.