![]() The conformal polymer coating is prepared through chemical vapor deposition. SSY is composed of columnar aggregates of organic, plank-like molecules in water. Our chiral symmetry-breaking experiments use Sunset Yellow FCF (SSY), a lyotropic chromonic LC (LCLC) with small twist elastic constant, in polymer-coated capillaries. The configurations that we report on have homeotropic boundary conditions, and their chirality is not of molecular origin (i.e., handedness is not derived from chiral mesogens or dopants). However, this system differs significantly from earlier work. This general class of configuration has been investigated in cylinders ( 47– 52). In this paper, we introduce chiral symmetry-broken configurations of nematic LCs in a cylindrical confinement geometry, and we explore the energetics of the configurations and their defects. In addition, the system of a broken chiral symmetry often consists of domains of opposite handedness with defects separating the domains. Examples of these pathways include packing with multiple competing length scales ( 8– 10, 23, 24), reconfiguration through mechanical instabilities of periodic structures ( 20, 25, 26), and helix formation of flexible cylinders through inter- and intracylinder interactions ( 27, 28). Recently and in a different vein, identification and elucidation of pathways by which achiral building blocks spontaneously organize to create chiral structures have become an area of active study. To date, considerable effort has been expended to control handedness in materials (for example, by chiral separation of racemic mixtures or chiral amplification of small enantiomeric imbalances) ( 1, 8, 20– 22). When the chiral symmetry of an achiral system is broken, a handedness is established, and materials with different handedness commonly exhibit distinct and useful properties ( 10– 14) relevant for applications ranging from chemical sensors ( 15, 16) to photonics ( 17– 19). The emergence of chirality from achiral systems poses fundamental questions about which we have limited mechanistic understanding ( 1– 11). 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. 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. 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. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. 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. 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. ![]() Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. 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).
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