Topological Defects as Nucleation Points of the Nematic--Isotropic Phase Transition in Liquid Crystal Shells

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Hauptverfasser: Han, Yucen, Lagerwall, Jan, Majumdar, Apala
Format: Preprint
Veröffentlicht: 2024
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author Han, Yucen
Lagerwall, Jan
Majumdar, Apala
author_facet Han, Yucen
Lagerwall, Jan
Majumdar, Apala
contents The transition from a nematic to an isotropic state in a self-closing spherical liquid crystal shell with tangential alignment is a stimulating phenomenon to investigate, as the topology dictates that the shell exhibits local isotropic points at all temperatures in the nematic phase range, in the form of topological defects. The defects may thus be expected to act as nucleation points for the phase transition upon heating beyond the bulk nematic stability range. Here we study this peculiar transition, theoretically and experimentally, for shells with two different configurations of four +1/2 defects, finding that the defects act as the primary nucleation points if they are co-localized in each other's vicinity. If the defects are instead spread out across the shell, they again act as nucleation points, albeit not necessarily the primary ones. Beyond adding to our understanding of how the orientational order--disorder transition can take place in the shell geometry, our results have practical relevance for, e.g., the use of curved liquid crystals in sensing applications or for liquid crystal elastomer actuators in shell shape, undergoing a shape change as a result of the nematic--isotropic transition.
format Preprint
id arxiv_https___arxiv_org_abs_2402_00552
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Topological Defects as Nucleation Points of the Nematic--Isotropic Phase Transition in Liquid Crystal Shells
Han, Yucen
Lagerwall, Jan
Majumdar, Apala
Soft Condensed Matter
The transition from a nematic to an isotropic state in a self-closing spherical liquid crystal shell with tangential alignment is a stimulating phenomenon to investigate, as the topology dictates that the shell exhibits local isotropic points at all temperatures in the nematic phase range, in the form of topological defects. The defects may thus be expected to act as nucleation points for the phase transition upon heating beyond the bulk nematic stability range. Here we study this peculiar transition, theoretically and experimentally, for shells with two different configurations of four +1/2 defects, finding that the defects act as the primary nucleation points if they are co-localized in each other's vicinity. If the defects are instead spread out across the shell, they again act as nucleation points, albeit not necessarily the primary ones. Beyond adding to our understanding of how the orientational order--disorder transition can take place in the shell geometry, our results have practical relevance for, e.g., the use of curved liquid crystals in sensing applications or for liquid crystal elastomer actuators in shell shape, undergoing a shape change as a result of the nematic--isotropic transition.
title Topological Defects as Nucleation Points of the Nematic--Isotropic Phase Transition in Liquid Crystal Shells
topic Soft Condensed Matter
url https://arxiv.org/abs/2402.00552