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Jeong, Joonwoo
Experimental Soft Matter Physics Lab (SOPHY)
Research Interests
  • Liquid crystals, polymers, colloids, emulsions, pattern formation, microfluidics, microfabrication, optical microscopy

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Chiral structures from achiral liquid crystals in cylindrical capillaries

Cited 4 times inthomson ciCited 2 times inthomson ci
Title
Chiral structures from achiral liquid crystals in cylindrical capillaries
Author
Jeong, JoonwooKang, LouisDavidson, Zoey S.Collings, Peter J.Lubensky, Tom C.Yodh, A. G.
Keywords
mirror symmetry; parity symmetry; topological defects; chiral defects
Issue Date
2015-04
Publisher
NATL ACAD SCIENCES
Citation
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v.112, no.15, pp.E1837 - E1844
Abstract
We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects
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DOI
10.1073/pnas.1423220112
ISSN
0027-8424
Appears in Collections:
PHY_Journal Papers
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