Effects of chiral dopants on double-twist configurations of lyotropic chromonic liquid crystals in a cylindrical cavity

Eun, Jonghee; Kim, Sung-Jo; Jeong, Joonwoo

doi:10.1103/physreve.100.012702

Cited by 20 publications

(19 citation statements)

References 45 publications

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“…In capillaries of the radius R with degenerate planar anchoring, LCLCs exhibit the DT configuration sketched in Fig. 1A following the director n = − sin β(r )e φ + cos β(r )ez in a cylindrical coordinate (r , φ, z ) and β1 = β(r = R) at the capillary wall (53,54,56,61). The planar anchoring means that the surface director n lies on the capillary wall, and its degeneracy denotes that the director feels no anisotropy on the anchoring surface.…”

Section: Resultsmentioning

confidence: 99%

“…Unless specified otherwise, all concentrations in % means "% (wt/wt)." Materials and Methods and Eun et al (56) give further experimental details. In Fig.…”

Section: Resultsmentioning

confidence: 99%

“…1E, Bottom) based on the numerically calculated director field model to be explained. Note that the Jones calculus adopting the paraxial approximation has been used successfully for LCLC studies even in curved confining geometries, thanks to LCLC's relatively small birefringence, for example, −0.018 for DSCG, and the refractive index−matching techniques (53,56,58,59,61).…”

Section: Resultsmentioning

confidence: 99%

“…For a given K2/K3 and q0, we numerically solve Eq. 1, find multiple solutions, and compare their total energies to identify the ground state having the lowest energy (56). Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The majority of experimental systems hitherto studied are based on thermotropic LCs with typical elastic and surfaceanchoring properties. The aqueous LCLCs exhibiting unusual elastic properties, that is, very small twist modulus K2 and large saddle-splay modulus K24 (51-56), often leading to chiral symmetry breaking of confined achiral LCLCs (53,54,(56)(57)(58)(59)(60)(61), may enable us to access uncharted configurations and defects of topological interests. For instance, in the layer configuration by cholesteric LCLCs doped with chiral molecules, their small K2 provides energetic flexibility to the thickness of the cholesteric layer, that is, the repeating structure where the director n twists by π.…”

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confidence: 99%

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Layering transitions and metastable structures of cholesteric liquid crystals in cylindrical confinement

Eun

Pollard

Kim

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Our study of cholesteric lyotropic chromonic liquid crystals in cylindrical confinement reveals the topological aspects of cholesteric liquid crystals. The double-twist configurations we observe exhibit discontinuous layering transitions, domain formation, metastability, and chiral point defects as the concentration of chiral dopant is varied. We demonstrate that these distinct layer states can be distinguished by chiral topological invariants. We show that changes in the layer structure give rise to a chiral soliton similar to a toron, comprising a metastable pair of chiral point defects. Through the applicability of the invariants we describe to general systems, our work has broad relevance to the study of chiral materials.

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Section: Resultsmentioning

confidence: 99%

“…Unless specified otherwise, all concentrations in % means "% (wt/wt)." Materials and Methods and Eun et al (56) give further experimental details. In Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…For a given K2/K3 and q0, we numerically solve Eq. 1, find multiple solutions, and compare their total energies to identify the ground state having the lowest energy (56). Fig.…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Layering transitions and metastable structures of cholesteric liquid crystals in cylindrical confinement

Eun

Pollard

Kim

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Stability Against the Odds: The Case of Chromonic Liquid Crystals

Paparini

Virga

2022

J Nonlinear Sci

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The ground state of chromonic liquid crystals, as revealed by a number of recent experiments, is quite different from that of ordinary nematic liquid crystals: it is twisted instead of uniform. The common explanation provided for this state within the classical elastic theory of Frank demands that one Ericksen’s inequality is violated. Since in general such a violation makes Frank’s elastic free-energy functional unbounded below, the question arises as to whether the twisted ground state can be locally stable. We answer this question in the affirmative. In reaching this conclusion, a central role is played by the specific boundary conditions imposed in the experiments on the boundary of rigid containers and by a general formula that we derive here for the second variation in Frank’s elastic free energy.

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An Elastic Quartic Twist Theory for Chromonic Liquid Crystals

Paparini

Virga

2023

J Elast

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Chromonic liquid crystals are lyotropic materials which are attracting growing interest for their adaptability to living systems. To describe their elastic properties, the classical Oseen-Frank theory requires anomalously small twist constants and (comparatively) large saddle-splay constants, so large as to violate one of Ericksen’s inequalities, which guarantee that the Oseen-Frank stored-energy density is bounded below. While such a violation does not prevent the existence and stability of equilibrium distortions in problems with fixed geometric confinement, the study of free-boundary problems for droplets has revealed a number of paradoxical consequences. Minimizing sequences driving the total energy to negative infinity have been constructed by employing ever growing needle-shaped tactoids incorporating a diverging twist (Paparini and Virga in Phys. Rev. E 106: 044703, 2022). To overcome these difficulties, we propose here a novel elastic theory that extends for chromonics the classical Oseen-Frank stored energy by adding a quartic twist term. We show that the total energy of droplets is bounded below in the quartic twist theory, so that the known paradoxes are ruled out. The quartic term introduces a phenomenological length "Equation missing" in the theory; this affects the equilibrium of chromonics confined within capillary tubes. Use of published experimental data allows us to estimate "Equation missing".

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Effects of chiral dopants on double-twist configurations of lyotropic chromonic liquid crystals in a cylindrical cavity

Cited by 20 publications

References 45 publications

Layering transitions and metastable structures of cholesteric liquid crystals in cylindrical confinement

Layering transitions and metastable structures of cholesteric liquid crystals in cylindrical confinement

Stability Against the Odds: The Case of Chromonic Liquid Crystals

An Elastic Quartic Twist Theory for Chromonic Liquid Crystals

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