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2020-02-24

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cc-by (c) Ignés i Mullol, Jordi et al., 2020
Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/168438

Stable and metastable patterns in chromonic nematic liquid crystal droplets forced with static and dynamic magnetic fields

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Recurs relacionat

https://doi.org/10.3390/cryst10020138

Resum

Spherical confinement of nematic liquid crystals leads to the formation of equilibrium director field configurations that include point and line defects. Driving these materials with flows or dynamic fields often results in the formation of alternative metastable states. In this article, we study the effect of magnetic field alignment, both under static and dynamic conditions, of nematic gems (nematic droplets in coexistence with the isotropic phase) and emulsified nematic droplets of a lyotropic chromonic liquid crystal. We use a custom polarizing optical microscopy assembly that incorporates a permanent magnet whose strength and orientation can be dynamically changed. By comparing simulated optical patterns with microscopy images, we measure an equilibrium twisted bipolar pattern within nematic gems that is only marginally different from the one reported for emulsified droplets. Both systems evolve to concentric configurations upon application of a static magnetic field, but behave very differently when the field is rotated. While the concentric texture within the emulsified droplets is preserved and only displays asynchronous oscillations for high rotating speeds, the nematic gems transform into a metastable untwisted bipolar configuration that is memorized by the system when the field is removed. Our results demonstrate the importance of boundary conditions in determining the dynamic behavior of confined liquid crystals even for configurations that share similar equilibrium bulk structures.

Matèries

Cristalls líquids, Camps magnètics, Emulsions

Matèries (anglès)

Liquid crystals, Magnetic fields, Emulsions

Citació

Col·leccions

Articles publicats en revistes (Ciència dels Materials i Química Física)

Citació

IGNÉS I MULLOL, Jordi, et al. Stable and metastable patterns in chromonic nematic liquid crystal droplets forced with static and dynamic magnetic fields. Crystals. 2020. Vol. 10, num. 2, pags. 138. ISSN 2073-4352. [consulted: 17 of August of 2026]. Available at: https://hdl.handle.net/2445/168438

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