Energetics of Disclinations in Liquid Crystals

Ranganath, G. S.

doi:10.1080/00268948308073141

Cited by 23 publications

(15 citation statements)

References 24 publications

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“…5(c)] just reveals the deduced result that K 33 9 & K 11 (the relationship for SWNTs are valued consistent with that for MWNTs in our experiments), with the central region rich in splay. [28][29][30] Similar observations can also be detected from [Fig. 4(b)].…”

Section: Effects Of Elastic Anisotropy (K 11 ? K 33 ) On Defectssupporting

confidence: 86%

Bending Deformation Mechanism and Defective Properties of Liquid Crystalline Carbon Nanotubes in Evaporating Droplets

Chang

Liu

et al. 2011

RSC Adv.

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Here, we explore the liquid crystalline behavior of carbon nanotubes (CNTs) through two types of commonly physical parameters (the Frank elastic constants k ii (i = 1, 2, 3) in the liquid crystal field that typically describe the nature of molecular orientation, and the Young's modulus E that characterizes the peculiar mechanical properties of CNTs). Droplets of aqueous multiwall carbon nanotube (MWNT) suspensions are evaporated on silica wafer at room temperature in air and the resultant deposits exhibit the hallmark property of liquid crystalline formation, birefringence. And scanning electron microscopic (SEM) characterization further presents the concentric bending arrangement of MWNTs along the circumference at the edge. Then in analogy with liquid crystals, based upon the restraint of circular boundary as in the model of droplets, the CNTs' Frank elasticity is introduced and expresses the relationship with E, showing the dependence of nanotube rigidity and dimensions. By comparing the values of plane parameters k 11 and k 33 , defective properties about CNT-assemblies are provided, with Frank elastic constant anisotropy (k 11 ? k 33 ) contributing to their various distortion structures in the central core of the defects.

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Section: Effects Of Elastic Anisotropy (K 11 ? K 33 ) On Defectssupporting

confidence: 86%

Bending Deformation Mechanism and Defective Properties of Liquid Crystalline Carbon Nanotubes in Evaporating Droplets

Chang

Liu

et al. 2011

RSC Adv.

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“…In general, smectic-C films have different elastic constants for splay and bend deformations. The difference between elastic constants is already known to affect the structure of defects in a 2D liquid crystal [26][27][28], as well as the relative speed of positive and negative topological charges [16,17]. Here, we show that it can also create S-shaped annihilation trajectories, which is the same ef-fect as a non-optimal relative orientation of the defects.…”

Section: Introductionmentioning

confidence: 54%

Annihilation trajectory of defects in smectic-C films

Tang,

Selinger

2020

Preprint

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In a 2D liquid crystal, each topological defect has a topological charge and a characteristic orientation, and hence can be regarded as an oriented particle. Theories predict that the trajectories of annihilating defects depend on their relative orientation. Recently, these predictions have been tested in experiments on smectic-C films. Those experiments find curved trajectories that are similar to the predictions, but the detailed relationship between the defect orientations and the far-field director is different. To understand this difference, we extend the previous theories by adding the effects of elastic anisotropy, and find that it significantly changes the curved trajectories.

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“…Due to the fact, that in twist disclinations a director twist is introduced, the reflection symmetry is broken. According to Ranganath, Anisimov, and Dzyaloshinskii, in usual nematic LCs the non-chiral wedge dislination is energetically favoured upon the chiral twist disclination, except a very small twist elastic constant comes into play [34,35]. Connecting two half-unit twist disclinations in a capillary confinement, a director field profile suggested as in Figure 6(d-f) emerges, with an additional transverse twist along the capillary diameter between the two twist disclinations.…”

Section: Twisted Polar Configurationmentioning

confidence: 87%

Lyotropic nematic liquid crystals: interplay between a small twist elastic constant and chirality effects under confined geometries

Dietrich

2021

Liquid Crystals Today

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There are two classes of liquid crystals (LCs): Thermotropic LCs where the organic molecule represents the anisotropically shaped mesogen and lyotropic LCs, where the mesogens are nonspherical supramolecular assemblies dispersed in a solvent. Various kinds of lyotropic nematic liquid crystals (LLCs) exist, differing in shape and composition of the aggregates: Chromonic, polymeric or micellar LLCs.However, micellar LLCs are the most ubiquitous kind of LLCs, occurring in soaps and biological systems. Although these nematic lyotropics are so different, they exhibitcontrary to thermotropic nematics -spontaneous reflection symmetry breaking under confinement. We discuss spontaneous mirror symmetry breaking under capillary confinement for a standard micellar N D phase and give a detailed director field structure of the twisted polar configuration. Furthermore, we measure for the first time a complete set of viscoelastic properties of a micellar nematic LLC, finding a small twist elastic constant K 22 , which is at least one order of magnitude smaller than K 11 and K 33 . As demonstrated by the following work, a small K 22 and therefore spontaneous mirror symmetry breaking under confinement is rather the rule than the exception in lyotropic nematics and constitutes a unique difference between lyotropic and typical thermotropic nematics, for which the well-known one-constant approximation holds.

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Energetics of Disclinations in Liquid Crystals

Cited by 23 publications

References 24 publications

Bending Deformation Mechanism and Defective Properties of Liquid Crystalline Carbon Nanotubes in Evaporating Droplets

Bending Deformation Mechanism and Defective Properties of Liquid Crystalline Carbon Nanotubes in Evaporating Droplets

Annihilation trajectory of defects in smectic-C films

Lyotropic nematic liquid crystals: interplay between a small twist elastic constant and chirality effects under confined geometries

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