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Kim J, Jeong J. Confinement twists achiral liquid crystals and causes chiral liquid crystals to twist in the opposite handedness: cases in and around sessile droplets. SOFT MATTER 2024; 20:1361-1368. [PMID: 38252544 DOI: 10.1039/d3sm01283b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
We study the chiral symmetry breaking and metastability of confined nematic lyotropic chromonic liquid crystals (LCLCs) with and without chiral dopants. The isotropic-nematic coexistence phase of the LCLC renders two confining geometries: sessile isotropic (I) droplets surrounded by the nematic (N) phase and sessile nematic droplets immersed in the isotropic background. In the achiral system with no dopants, LCLC's elastic anisotropy and topological defects induce a spontaneous twist deformation to lower the energetic penalty of splay deformation, resulting in spiral optical textures under crossed polarizers both in the I-in-N and N-in-I systems. While the achiral system exhibits both handednesses with an equal probability, a small amount of the chiral dopant breaks the balance. Notably, in contrast to the homochiral configuration of a chirally doped LCLC in the bulk, the spiral texture of the disfavored handedness appears with a finite probability both in the I-in-N and N-in-I systems. We propose director field models explaining how chiral symmetry breaking arises by the energetics and the opposite-twist configurations exist as meta-stable structures in the energy landscape. These findings help us create and control chiral structures using confined LCs with large elastic anisotropy.
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Affiliation(s)
- Jungmyung Kim
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
| | - Joonwoo Jeong
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
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Brumby PE, Kowaguchi A, Nozawa T, Yasuoka K, Wensink HH. Pre-Smectic Ordering and the Unwinding Helix in Monte Carlo Simulations of Cholesteric Liquid-Crystals. J Phys Chem B 2023; 127:7194-7204. [PMID: 37540189 DOI: 10.1021/acs.jpcb.3c02018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
In this paper, molecular chirality is studied for liquid-crystal fluids represented by hard rods with the addition of an attractive chiral dispersion term. Chiral forces between molecular pairs are assumed to be long-ranged and are described in terms of the pseudotensor of Goossens [W. J. A. Goossens, Mol. Cryst. Liq. Cryst. 1971, 12, 237-244]. Following Varga and Jackson [S. Varga and G. Jackson, Chem. Phys. Lett. 2003, 377, 6-12], this is combined with a hard-spherocylinder core. We investigate the relationship between molecular chirality and the helical pitch of the system, which occurs in the absence of full three-dimensional periodic boundary conditions. The dependence of the wavenumber of this pitch on the thermodynamic variables, temperature, and density is measured. We also explore the use of a novel surface boundary interaction model. As a result of this approach, we are able to lower the temperature of the system without the occurrence of nematic droplets, which would interfere with the formation of a uniaxial pitch. Regarding the theoretical predictions of Wensink and Jackson [H. H. Wensink and G. Jackson, J. Chem. Phys. 2009, 130, 234911], on the one hand, we have qualitative agreement with the observed non-monotonic density dependence of the wavenumber. Initially increasing with density, the wavenumber reaches a maximum, before falling as the density moves toward the point of phase transition from cholesteric to smectic. However, further analysis for shorter rods, in the presence of novel boundary conditions, reveals some disagreement with the theory, at least in this case; the unwinding of the cholesteric helix in the cholesteric phase occurs simultaneously with subtle increases in smectic ordering. These pre-smectic fluctuations have not been accounted for so far in theories on cholesterics but turn out to play a key role in controlling the pitch of cholesteric phases of rod-shaped mesogens with a small to moderate aspect ratio.
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Affiliation(s)
- Paul E Brumby
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Akie Kowaguchi
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Takuma Nozawa
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Kenji Yasuoka
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Henricus H Wensink
- Laboratoire de Physique des Solides─UMR 8502, Université Paris-Saclay & CNRS, Orsay 91405, France
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3
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Li S, Zhou X, Zhu J, Du K, Du Y, Gao H. Local chiral inversion of chiral nematic liquid crystals in cylinders. Phys Rev E 2023; 107:034705. [PMID: 37073040 DOI: 10.1103/physreve.107.034705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/03/2023] [Indexed: 04/20/2023]
Abstract
On the basis of Landau-de Gennes theory and the finite-difference iterative method, the autonomic modulation of chiral inversion in a cylindrical cavity with degenerate planar anchoring is investigated. Under the applied helical twisting power (inversely related to the pitch P), a chiral inversion can be achieved due to the nonplanar geometry effect, and the inversion capacity rises with the increase of the helical twisting power. The combined effect of the saddle-splay K_{24} contribution (corresponding to the L_{24} term in Landau-de Gennes theory) and the helical twisting power are analyzed. It is found that the chiral inversion is more strongly modulated on the condition that the chirality of spontaneous twist is opposite to that of applied helical twisting power. Further, larger values of K_{24} will induce larger modulation of the twist degree and smaller modulation of the inverted region. The autonomic modulation of chiral inversion shows great potential for chiral nematic liquid crystal materials to be used in smart devices, such as light-controlled switches and nanoparticle transporters.
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Affiliation(s)
- Shuting Li
- School of Science, Hebei University of Technology, Tianjin 300401, People Republic of China
| | - Xuan Zhou
- School of Science, Hebei University of Technology, Tianjin 300401, People Republic of China
| | - Jiliang Zhu
- School of Science, Hebei University of Technology, Tianjin 300401, People Republic of China
| | - Kaiyang Du
- School of Science, Hebei University of Technology, Tianjin 300401, People Republic of China
| | - Yike Du
- School of Science, Hebei University of Technology, Tianjin 300401, People Republic of China
| | - Han Gao
- School of Science, Hebei University of Technology, Tianjin 300401, People Republic of China
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Yang D, Jin C, Kang H. Vertical Alignment of Liquid Crystal on Sustainable 2,4-Di- tert-butylphenoxymethyl-Substituted Polystyrene Films. Polymers (Basel) 2022; 14:polym14071302. [PMID: 35406176 PMCID: PMC9002882 DOI: 10.3390/polym14071302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/11/2022] [Accepted: 03/21/2022] [Indexed: 02/04/2023] Open
Abstract
We synthesized sustainable 2,4-di-tert-butylphenoxymethyl-substituted polystyrenes (PDtBP#, # = 88, 68, 35, and 19, where # is molar percent contents of 2,4-di-tert-butylphenoxymethyl moiety), using post-polymerization modification reactions in order to study their liquid crystal (LC) alignment behaviors. In general, LC cells fabricated using polymer film with higher molar content of 2,4-di-tert-butylphenoxymethyl side groups showed vertical LC alignment behavior. LC alignment behavior in LC cell was related to the surface energy of the polymer alignment layer. For example, when the total surface energy value of the polymer layer was smaller than about 29.4 mJ/m2, vertical alignment behaviors were observed, generated by the nonpolar 2,4-di-tert-butylphenoxymethyl moiety with long and bulky carbon groups. Orientation stability was observed at 200 °C in the LC cells fabricated using PDtBP88 as the LC alignment layer. Therefore, as a natural compound modified polymer, PDtBP# can be used as a candidate LC alignment layer for environmentally friendly applications.
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Affiliation(s)
| | | | - Hyo Kang
- Correspondence: ; Tel.: +82-51-200-7720; Fax: +82-51-200-7728
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Paparini S, Virga EG. Shape bistability in 2D chromonic droplets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:495101. [PMID: 34517353 DOI: 10.1088/1361-648x/ac2645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 09/13/2021] [Indexed: 06/13/2023]
Abstract
An extensive experimental study of the shapes of two-dimensional bipolar droplets of the chromonic nematic phase of disodium cromoglycate (DSCG) sandwiched between glass plates, by Kimet alwas published in (2013J. Phys.: Condens. Matter25404202). The paper includes a mathematical model of this system. We have extended this study by further theoretical modelling. Our results are in good, quantitative agreement with the experimental data. The model has produced what promises to be a more accurate estimate for the isotropic surface tension at the nematic/isotropic solution interface-and predicts a regime of shape bistability (which has not yet been observed) for larger droplets, where tactoids (pointed, zeppelin-shaped droplets) and smooth-edged discoids can coexist in equilibrium. The general method presented in this paper is also applied to the tactoids formed by F-actin filaments in solution, for which an estimate is given for the value of the isotropic surface tension at the nematic/isotropic interface.
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Affiliation(s)
- Silvia Paparini
- Dipartimento di Matematica, Università di Pavia, Via Ferrata 5, 27100 Pavia, Italy
| | - Epifanio G Virga
- Dipartimento di Matematica, Università di Pavia, Via Ferrata 5, 27100 Pavia, Italy
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Ando JK, Collings PJ. A chiral-racemic lyotropic chromonic liquid crystal system. SOFT MATTER 2021; 17:1409-1414. [PMID: 33325978 DOI: 10.1039/d0sm02013c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The two main classes of liquid crystals are thermotropic (containing no solvent) and lyotropic (containing solvent). Both of these classes possess the nematic phase, the most simple of liquid crystal phases with only uniaxial orientational order. For both of these classes, if the constituent molecules are chiral or if a chiral dopant is added, the preferred direction of orientation rotates in helical fashion in what is called the chiral nematic phase. Recent research has shown that because the ordering entities of the two classes are quite different (molecules versus molecular assemblies), important differences in the properties of the nematic phase can result. While thermotropic chiral nematics have been extensively examined, less is known about lyotropic chiral nematics, especially for the most ideal case, a chiral-racemic system. Furthermore, none of the lyotropic chiral-racemic studies has included lyotropic chromonic liquid crystals, which are solutions of dyes, drugs, and nucleic acids. Inverse pitch measurements are reported for a chiral-racemic system of a chromonic liquid crystal across the entire chiral fraction range and over a 30 °C temperature interval. The inverse pitch depends linearly on chiral fraction and decreases with increasing temperature, indicating that achiral and chiral molecules participate in the assembly structure similarly. The helical twisting power is significantly larger than for other chiral lyotropic liquid crystals due to the very high scission energy of the investigated system.
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Affiliation(s)
- Jordan K Ando
- Department of Physics & Astronomy, Swarthmore College, Swarthmore, PA, USA.
| | - Peter J Collings
- Department of Physics & Astronomy, Swarthmore College, Swarthmore, PA, USA. and Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
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Bosire R, Ndaya D, Kasi RM. Recent progress in functional materials from lyotropic chromonic liquid crystals. POLYM INT 2020. [DOI: 10.1002/pi.6113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Reuben Bosire
- Department of Chemistry University of Connecticut Storrs CT USA
| | - Dennis Ndaya
- Department of Chemistry University of Connecticut Storrs CT USA
| | - Rajeswari M Kasi
- Department of Chemistry University of Connecticut Storrs CT USA
- Polymer Program, Institute of Material Science University of Connecticut Storrs CT USA
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Altınay Y, Nesrullajev A. Lyotropic Lamellar Mesophase. Magneto-Morphologic Transforma tions and Optical Refracting Properties: Effect of Optically Active Dopants. TENSIDE SURFACT DET 2020. [DOI: 10.3139/113.110662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Effect of optically active dopants on the morphologic and optical refracting properties of the lyotropic liquid crystalline mesophase with anisometric micelles has been investigated. Lyotropic lamellar mesophases, which are formed by the plate-like micelles of quasi-indef inite diameter, were objects of the investigations. Wine acid (WA) and tartaric acid (TA) were used as the optically active dopants. Texture transformations under influence of an external magnetic field and time and temperature changes of these textures for quaternary mixtures with various concentrations of the optically active dopants have been studied. Unusual textures with the spherical microdroplet formations have been found and studied. The optical refracting properties of ternary and quaternar y lyotropic systems vs. temperature and concentration were investigated.
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Wensink HH. Polymeric Nematics of Associating Rods: Phase Behavior, Chiral Propagation, and Elasticity. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01421] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Henricus H. Wensink
- Laboratoire de Physique des Solides—UMR 8502, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
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Matus Rivas OM, Rey AD. Molecular Dynamics Study of the Effect of l-Alanine Chiral Dopants on Diluted Chromonic Solutions. J Phys Chem B 2019; 123:8995-9010. [PMID: 31525883 DOI: 10.1021/acs.jpcb.9b06111] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atomistic molecular dynamics simulations have been performed for disodium cromoglycate (DSCG) chromonic solutions mixed with l-alanine chiral dopants. We study the fundamental molecular mechanisms induced by low concentrations of l-alanine on diluted DSCG solutions, including their effect on the chromonic aggregates, the solvent, and sodium counterions. Simulations reveal that l-alanine molecules primarily interact with DSCG stacks establishing salt bridges between their respective ammonium and carboxylate groups. Our results demonstrate that l-alanine and sodium counterions jointly establish an intricate network of noncovalent interactions around DSCG aggregates that decreases the global electrostatic repulsion of the chromonic system. Two possible structural effects in DSCG aggregates arise from this electronic stabilization: the increment of the total number of consecutively stacked aromatic planes per DSCG aggregate (intracolumnar effect) or the partial separation reduction between neighboring DSCG columnar sections due to the simultaneous bridging of intercolumnar DSCG carboxylate sites by sodium counterions, forming sodium bridges (intercolumnar effect). Sodium bridges may be responsible for the formation of stacking faults in DSCG aggregates in the form of lateral overlap junctions. This mechanism would explain the difference between lower X-ray correlation lengths with the expected persistence length in chromonics.
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Affiliation(s)
- Oscar M Matus Rivas
- Department of Chemical Engineering , McGill University , Montreal , Quebec H3A 0C5 , Canada
| | - Alejandro D Rey
- Department of Chemical Engineering , McGill University , Montreal , Quebec H3A 0C5 , Canada
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Das P, Praveen PL. Solvent polarity and chain length effects in thermotropic mesophase formation process: Comparative quantum and thermodynamic analysis. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Eun J, Kim SJ, Jeong J. Effects of chiral dopants on double-twist configurations of lyotropic chromonic liquid crystals in a cylindrical cavity. Phys Rev E 2019; 100:012702. [PMID: 31499771 DOI: 10.1103/physreve.100.012702] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Indexed: 06/10/2023]
Abstract
We investigate how chiral dopants affect the chiral symmetry breaking of lyotropic chromonic liquid crystals (LCLCs) focusing on the double-twist (DT) director configurations in a cylindrical capillary. LCLCs of unusual elastic properties tend to exhibit chiral director configurations under confinement despite the absence of intrinsic chirality. The DT director configuration in a cylindrical cavity with a degenerate planar anchoring, resulting from the large saddle-splay-to-twist elastic modulus ratio, is a representative example. Here we start by reexamining the DT configuration of nematic disodium cromoglycate in a cylindrical capillary and estimate the ratio of saddle splay to bend modulus K_{24}/K_{3}=0.5±0.1. Additionally, we study the DT configurations of the chiral nematic LCLCs with chiral dopants. The DT configuration becomes homochiral when the dopant concentration surpasses the critical concentration. We characterize these chiral DT configurations and provide a theoretical model on their energetics. Finally, we observe how the enantiomeric excess of chiral dopants determines the director configuration when dopants of two different handednesses are mixed.
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Affiliation(s)
- Jonghee Eun
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Sung-Jo Kim
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, Republic of Korea
| | - Joonwoo Jeong
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, Republic of Korea
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