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Bagchi K, Emeršič T, Martínez-González JA, de Pablo JJ, Nealey PF. Functional soft materials from blue phase liquid crystals. SCIENCE ADVANCES 2023; 9:eadh9393. [PMID: 37494446 PMCID: PMC10371026 DOI: 10.1126/sciadv.adh9393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 06/27/2023] [Indexed: 07/28/2023]
Abstract
Blue phase (BP) liquid crystals are chiral fluids wherein millions of molecules self-assemble into cubic lattices that are on the order of hundred nanometers. As the unit cell sizes of BPs are comparable to the wavelength of light, they exhibit selective Bragg reflections in the visible. The exploitation of the photonic properties of BPs for technological applications is made possible through photopolymerization, a process that renders mechanical robustness and thermal stability. We review here the preparation and characterization of stimuli-responsive, polymeric photonic crystals based on BPs. We highlight recent studies that demonstrate the promise that polymerized BP photonic crystals hold for colorimetric sensing and dynamic light control. We review using Landau-de Gennes simulations for predicting the self-assembly of BPs and the potential for using theory to guide experimental design. Finally, opportunities for using BPs to synthesize new soft materials, such as highly structured polymer meshes, are discussed.
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Affiliation(s)
- Kushal Bagchi
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Tadej Emeršič
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - José A Martínez-González
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, Av. Parque Chapultepec 1570, San Luis Potosí 78210 SLP, Mexico
| | - Juan J de Pablo
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Paul F Nealey
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
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2
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Cordoyiannis G, Lavrič M, Tzitzios V, Trček M, Lelidis I, Nounesis G, Kralj S, Thoen J, Kutnjak Z. Experimental Advances in Nanoparticle-Driven Stabilization of Liquid-Crystalline Blue Phases and Twist-Grain Boundary Phases. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:2968. [PMID: 34835732 PMCID: PMC8618027 DOI: 10.3390/nano11112968] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 10/28/2021] [Accepted: 11/03/2021] [Indexed: 01/04/2023]
Abstract
Recent advances in experimental studies of nanoparticle-driven stabilization of chiral liquid-crystalline phases are highlighted. The stabilization is achieved via the nanoparticles' assembly in the defect lattices of the soft liquid-crystalline hosts. This is of significant importance for understanding the interactions of nanoparticles with topological defects and for envisioned technological applications. We demonstrate that blue phases are stabilized and twist-grain boundary phases are induced by dispersing surface-functionalized CdSSe quantum dots, spherical Au nanoparticles, as well as MoS2 nanoplatelets and reduced-graphene oxide nanosheets in chiral liquid crystals. Phase diagrams are shown based on calorimetric and optical measurements. Our findings related to the role of the nanoparticle core composition, size, shape, and surface coating on the stabilization effect are presented, followed by an overview of and comparison with other related studies in the literature. Moreover, the key points of the underlying mechanisms are summarized and prospects in the field are briefly discussed.
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Affiliation(s)
- George Cordoyiannis
- Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia; (M.L.); (M.T.); (Z.K.)
- Faculty of Mechanical Engineering, Czech Technical University in Prague, 16600 Prague 6, Czech Republic
| | - Marta Lavrič
- Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia; (M.L.); (M.T.); (Z.K.)
| | - Vasileios Tzitzios
- Institute of Nanoscience and Nanotechnology, National Centre for Scientific Research “Demokritos”, Aghia Paraskevi, 15310 Athens, Greece;
| | - Maja Trček
- Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia; (M.L.); (M.T.); (Z.K.)
| | - Ioannis Lelidis
- Faculty of Physics, National and Kapodistrian University of Athens, Zografou, 15784 Athens, Greece;
| | - George Nounesis
- Institute of Nuclear and Radiological Sciences and Technology, National Centre for Scientific Research “Demokritos”, Aghia Paraskevi, 15310 Athens, Greece;
| | - Samo Kralj
- Faculty of Natural Sciences, University of Maribor, 2000 Maribor, Slovenia;
| | - Jan Thoen
- Department of Physics and Astronomy, KU Leuven, 3001 Leuven, Belgium;
| | - Zdravko Kutnjak
- Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia; (M.L.); (M.T.); (Z.K.)
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3
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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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4
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Ogolla T, Paley RS, Collings PJ. Temperature dependence of the pitch in chiral lyotropic chromonic liquid crystals. SOFT MATTER 2018; 15:109-115. [PMID: 30534734 DOI: 10.1039/c8sm02091d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
One of the most simple cases in which chirality at the microscopic level produces a chiral macroscopic structure is the chiral nematic liquid crystal phase. In such a phase, the preferred direction of molecular orientation rotates in helical fashion, with the pitch of the helix in different systems ranging from around 100 nm to as large as can be measured (∼10 mm). For almost all thermotropic and lyotropic liquid crystals, the ordered entities are formed from strong bonds, so the pitch varies in accordance with how the interactions between these largely immutable entities are affected by changing conditions. A unique exception are lyotropic chromonic liquid crystals (LCLCs) that spontaneously form weakly bound assemblies in solution, the size of which depends strongly on experimental parameters. While the temperature dependence of the pitch has been measured for chiral LCLCs formed by short strands of DNA (DNA-LCLCs), such is not the case for chiral LCLCs formed by small molecules. Polarized optical microscopy experiments on small molecule chiral LCLCs reveal the changing assembly size through a temperature dependence of the pitch not typical for many other systems, including the most recent measurements on DNA-LCLCs. In fact, the pitch measurements in small molecule chiral LCLCs strongly increase in value as the temperature is increased and the assemblies shrink in size. Theoretical considerations provide some help in understanding this phenomena, but leave much to be explained.
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Affiliation(s)
- Timothy Ogolla
- Department of Physics & Astronomy, Swarthmore College, Swarthmore, PA, USA. and Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA, USA
| | - Robert S Paley
- Department of Chemistry and Biochemistry, 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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5
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Bukusoglu E, Bedolla Pantoja M, Mushenheim PC, Wang X, Abbott NL. Design of Responsive and Active (Soft) Materials Using Liquid Crystals. Annu Rev Chem Biomol Eng 2016; 7:163-96. [PMID: 26979412 DOI: 10.1146/annurev-chembioeng-061114-123323] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Liquid crystals (LCs) are widely known for their use in liquid crystal displays (LCDs). Indeed, LCDs represent one of the most successful technologies developed to date using a responsive soft material: An electric field is used to induce a change in ordering of the LC and thus a change in optical appearance. Over the past decade, however, research has revealed the fundamental underpinnings of potentially far broader and more pervasive uses of LCs for the design of responsive soft material systems. These systems involve a delicate interplay of the effects of surface-induced ordering, elastic strain of LCs, and formation of topological defects and are characterized by a chemical complexity and diversity of nano- and micrometer-scale geometry that goes well beyond that previously investigated. As a reflection of this evolution, the community investigating LC-based materials now relies heavily on concepts from colloid and interface science. In this context, this review describes recent advances in colloidal and interfacial phenomena involving LCs that are enabling the design of new classes of soft matter that respond to stimuli as broad as light, airborne pollutants, bacterial toxins in water, mechanical interactions with living cells, molecular chirality, and more. Ongoing efforts hint also that the collective properties of LCs (e.g., LC-dispersed colloids) will, over the coming decade, yield exciting new classes of driven or active soft material systems in which organization (and useful properties) emerges during the dissipation of energy.
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Affiliation(s)
- Emre Bukusoglu
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706;
| | - Marco Bedolla Pantoja
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706;
| | - Peter C Mushenheim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706;
| | - Xiaoguang Wang
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706;
| | - Nicholas L Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706;
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6
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Wang J, Shi Y, Yang K, Wei J, Guo J. Stabilization and optical switching of liquid crystal blue phase doped with azobenzene-based bent-shaped hydrogen-bonded assemblies. RSC Adv 2015. [DOI: 10.1039/c5ra12256b] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Stabilization and phototuning of the reflection color of BP I have been demonstrated in a BP-LCs by employing a new kind of bent-shaped H-bonded assemblies with azobenzene group.
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Affiliation(s)
- Jiao Wang
- College of Materials Science and Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Yang Shi
- College of Materials Science and Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Kuan Yang
- College of Materials Science and Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Jie Wei
- College of Materials Science and Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Jinbao Guo
- College of Materials Science and Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
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7
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Tiribocchi A, Henrich O, Lintuvuori JS, Marenduzzo D. Switching hydrodynamics in liquid crystal devices: a simulation perspective. SOFT MATTER 2014; 10:4580-4592. [PMID: 24865840 DOI: 10.1039/c4sm00042k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In liquid crystal devices it is important to understand the physics underlying their switching between different states, which is usually achieved by applying or removing an electric field. Flow is known to be a key determinant of the timescales and pathways of the switching kinetics. Incorporating hydrodynamic effects into theories for liquid crystal devices is therefore important; however this is also highly non-trivial, and typically requires the use of accurate numerical methods. Here, we review some recent advances in our theoretical understanding of the dynamics of switching in liquid crystal devices, mainly gained through computer simulations. These results, as we shall show, uncover interesting new physics, and may be important for future applications.
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Affiliation(s)
- A Tiribocchi
- SUPA, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JZ, UK.
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8
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Lin TH, Li Y, Wang CT, Jau HC, Chen CW, Li CC, Bisoyi HK, Bunning TJ, Li Q. Red, green and blue reflections enabled in an optically tunable self-organized 3D cubic nanostructured thin film. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:5050-5054. [PMID: 23913627 DOI: 10.1002/adma.201300798] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/30/2013] [Indexed: 06/02/2023]
Abstract
A new light-driven chiral molecular switch doped in a stable blue phase (BP) liquid crystal allows wide optical tunability of three-dimensional cubic nanostructures with a selective reflection wavelength that is reversibly tuned through the visible region. Moreover, unprecedented reversible light-directed red, green, and blue reflections of the self-organized three-dimensional cubic nanostructure in a single film are demonstrated for the first time. Additionally, unusual isothermal photo-stimulated less ordered BP II to more ordered BP I phase transition was observed in the system.
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Affiliation(s)
- Tsung-Hsien Lin
- Deaprtment of Photonics, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan
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9
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Chen HY, Lu SF, Hsieh YC. Unusual electro-optical behavior in a wide-temperature BPIII cell. OPTICS EXPRESS 2013; 21:9774-9779. [PMID: 23609684 DOI: 10.1364/oe.21.009774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A low driving voltage and fast response blue phase III (BPIII) liquid-crystal device with very low dielectric anisotropy is demonstrated. To stabilize BPIII in a wide temperature range (> 15°C), a chiral molecule with good solubility was chosen. By studying field-dependent polarization state of the transmitting light, it was found that the field-induced birefringence becomes saturated in the high field. However, the transmitting intensity exhibits a tendency to increase as the electric field increases. This indicates that the electro-optical behavior in BPIII device may be from the flexoelectric effect, which induces tilted optical axis and then induces birefringence. Because the phase transition from BPIII to chiral nematic phase does not happen, the device shows no hysteresis effect and no residual birefringence, exhibits fast response, and can be a candidate for fast photonic application.
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Affiliation(s)
- Hui-Yu Chen
- Department of Photonics, Feng Chia University, Taichung, Taiwan 40724, Republic of China.
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10
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Rossi M, Zanchetta G, Klussmann S, Clark NA, Bellini T. Propagation of chirality in mixtures of natural and enantiomeric DNA oligomers. PHYSICAL REVIEW LETTERS 2013; 110:107801. [PMID: 23521299 DOI: 10.1103/physrevlett.110.107801] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Indexed: 06/01/2023]
Abstract
Concentrated solutions of ultrashort duplex-forming DNA oligomers may develop various forms of liquid crystal ordering among which is the chiral nematic phase, characterized by a macroscopic helical precession of molecular orientation. The specifics of how chirality propagates from the molecular to the mesoscale is still unclear, both in general and in the case of DNA-based liquid crystals. We have here investigated the onset of nematic ordering and its chiral character in mixtures of natural D-DNA oligomers forming right-handed duplex helices and of mirror symmetric (L-DNA) molecules, forming left-handed helices. Since the nematic ordering of DNA duplexes is mediated by their end-to-end aggregation into linear columns, by controlling the terminals of both enantiomers we could study the propagation of chirality in solutions where the D and L species form mixtures of homochiral columns, and in solutions of heterochiral columns. The two systems behave in markedly different fashion. By adopting a simple model based on nearest-neighbor interactions, we account for the different observed dependence of the chirality of these two systems on the enantiomeric ratio.
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Affiliation(s)
- Marina Rossi
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, MI, Italy
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11
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Yoshizawa A. Material design for blue phase liquid crystals and their electro-optical effects. RSC Adv 2013. [DOI: 10.1039/c3ra43546f] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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12
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Chen X, Wang L, Li C, Xiao J, Ding H, Liu X, Zhang X, He W, Yang H. Light-controllable reflection wavelength of blue phase liquid crystals doped with azobenzene-dimers. Chem Commun (Camb) 2013; 49:10097-9. [DOI: 10.1039/c3cc46117c] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Henrich O, Stratford K, Cates ME, Marenduzzo D. Structure of blue phase III of cholesteric liquid crystals. PHYSICAL REVIEW LETTERS 2011; 106:107801. [PMID: 21469836 DOI: 10.1103/physrevlett.106.107801] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 11/16/2010] [Indexed: 05/30/2023]
Abstract
We report large scale simulations of the blue phases of cholesteric liquid crystals. Our results suggest a structure for blue phase III, the blue fog, which has been the subject of a long debate in liquid crystal physics. We propose that blue phase III is an amorphous network of disclination lines, which is thermodynamically and kinetically stabilized over crystalline blue phases at intermediate chiralities. This amorphous network becomes ordered under an applied electric field, as seen in experiments.
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Affiliation(s)
- O Henrich
- SUPA, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
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15
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Fukuda JI, Yoneya M, Yokoyama H. Simulation of cholesteric blue phases using a Landau-de Gennes theory: effect of an applied electric field. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:031706. [PMID: 19905130 DOI: 10.1103/physreve.80.031706] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Indexed: 05/28/2023]
Abstract
We investigate numerically static and dynamic properties of cholesteric blue phases. Our study is based on a Landau-de Gennes theory describing the orientational order of a liquid crystal in terms of a second-rank tensor. To find the shape and size of the unit cell conforming to the minimum of the free energy, we let the geometrical parameters characterizing the unit cell relax in the course of the time evolution via a simple relaxational equation. We investigate the effect of an electric field on the structure of cholesteric blue phases. We study how the deformation of the unit cell in response to the electric field E depends on the strength and direction of the electric field and the original structure of cholesteric blue phases. Our results qualitatively agree with the experimental findings. Although in a weak field, the strain tensor is proportional to E2 as previously argued, for a moderate field the distortion is no longer proportional to E2 and can be even nonmonotonic with respect to E2 . Furthermore, we investigate the kinetic processes of the deformation, rearrangement, and extinction of disclination lines under a strong electric field. We show that the kinetics of disclination lines is highly complicated and sensitively depends on the initial structure of blue phases, the direction of the electric field, and the sign of dielectric anisotropy epsilon(a). In most cases, a strong field aligns the liquid crystals in a uniform (positive epsilon(a)) or helical (negative epsilon(a)) manner without disclination lines. However, for negative epsilon(a) and the direction of the electric field parallel to the body diagonal of the unit cell, disclination lines do not disappear and form a two-dimensional hexagonal lattice.
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Affiliation(s)
- Jun-Ichi Fukuda
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568, Japan.
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16
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Mazars M. The chiral dipolar hard sphere model. Mol Phys 2009. [DOI: 10.1080/00268970902852640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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17
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Archer P, Dierking I, Hird M. Determination of the Landau potential of chiral enantiomer ferroelectric liquid crystal mixtures. SOFT MATTER 2007; 3:207-213. [PMID: 32680267 DOI: 10.1039/b613021f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The full Landau potential was determined for mixtures of the two chiral configurations of ferroelectric liquid crystal enantiomers. Experimental temperature and electric field dependent tilt and polarisation data are analysed a multi-curve fitting procedure to determine all the parameters of the generalised Landau model for ferroelectric liquid crystals. The three Landau coefficients , and as well as the bilinear coupling, , biquadratic coupling, and dielectric susceptibility, , were obtained as a function of enantiomeric excess. The chirality dependent bilinear coupling term vanishes as the chirality of the system tends to zero on approaching the racemic mixture. All other terms remain constant within the limits of error, providing experimental evidence that the bilinear coupling term is the only chirality dependent term of the generalised Landau model.
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Affiliation(s)
- Paul Archer
- School of Physics and Astronomy, University of Manchester, Schuster Laboratory, Oxford Road, Manchester, UKM13 9PL.
| | - Ingo Dierking
- School of Physics and Astronomy, University of Manchester, Schuster Laboratory, Oxford Road, Manchester, UKM13 9PL.
| | - Michael Hird
- Department of Chemistry, University of Hull, Hull, UKHU6 7RX
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18
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Jamée P, Pitsi G, Thoen J. First-order character of the smectic-A to chiral nematic transition in chiral liquid-crystal mixtures. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:031703. [PMID: 12689084 DOI: 10.1103/physreve.67.031703] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2002] [Indexed: 05/24/2023]
Abstract
An investigation into the smectic-A to chiral nematic (N'A) transition in liquid crystals is presented by using adiabatic scanning calorimetry (ASC). It is predicted theoretically that chirality drives this transition to first order. This transition is studied in mixtures of the nonchiral liquid crystal octyloxycyanobiphenyl (8OCB) and the chiral 4-(2-methylbutyl)-4(')-cyanobiphenyl (CB15), a system with a large (chiral) nematic region that widens upon increasing the chiral (CB15) fraction. An ASC measurement on pure 8OCB showed no evidence for a latent heat, in agreement with previous ac calorimetric studies, with an upper boundary for the latent heat (if any) of 1.8 J/kg. Since pure 8OCB has no measurable latent heat, and taking into account the widening of the chiral nematic region, the possibility of a continuous to first-order crossover due to the coupling of the nematic and the smectic order parameters, as occurring in several cases of smectic-A to nematic (NA) transitions, can be excluded. However, for all examined mixtures a latent heat could be determined at the smectic-A to chiral nematic transition. This confirms theoretical predictions of the first order character of this transition. Quantitatively, theoretical predictions of the evolution of the entropy discontinuities and latent heats of this transition were not consistent with the experimental results. It was further observed that the transition temperature decreases linearly in agreement with theoretical predictions and a previous ac calorimetric study. Finally, it was observed that the pretransitional specific heat capacity shows an interesting evolution upon increasing chiral fraction, and it may be concluded that any theoretical model based on Landau theory is not sufficient to describe this transition.
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Affiliation(s)
- P Jamée
- Laboratorium voor Akoestiek en Thermische Fysica, Departement Natuurkunde en Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
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19
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Jamee P, Pitsi G, Li M, Nguyen H, Sigaud G, Thoen J. Phase behavior and blue-phase-III-isotropic critical point in (R)-(S) mixtures of a chiral liquid crystal with a direct twist-grain-boundary to blue-phase transition. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 2000; 62:3687-93. [PMID: 11088884 DOI: 10.1103/physreve.62.3687] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/1999] [Indexed: 05/01/2023]
Abstract
We have investigated mixtures of the (R) and (S) enantiomers of a chiral liquid crystal, (R)- or (S)-1-methylheptyl 3'-fluoro-4'-(3-fluoro-4-octadecyloxybenzoyloxy)tolane-4-carboxylate using high-resolution adiabatic scanning calorimetry. The pure (R) compound has a direct transition from the twist-grain-boundary to the blue phase without an intermediary chiral nematic phase. For the blue phases a different kind of phase behavior as a function of enantiomeric excess is observed, most probably related to the presence of a twist-grain-boundary-A instead of a chiral nematic phase below the blue phases. The general form of this phase diagram is compared with traditional blue-phase behavior. Furthermore a blue-phase-III-isotropic phase critical point, analoguous to that of a liquid-gas system, is observed, consistent with experimental and theoretical work recently published in this field. Finally, the effect of changing enantiomeric excess on the latent heats of the different first order phase transitions is measured and discussed.
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Affiliation(s)
- P Jamee
- Laboratorium voor Akoestiek en Thermische Fysica, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium
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20
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Huff BP, Krich JJ, Collings PJ. Helix inversion in the chiral nematic and isotropic phases of a liquid crystal. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 2000; 61:5372-5378. [PMID: 11031587 DOI: 10.1103/physreve.61.5372] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/1999] [Revised: 12/10/1999] [Indexed: 05/23/2023]
Abstract
Measurements of the chirality (2 pi/pitch) in the chiral nematic phase and of a structural constant proportional to the chirality in the isotropic liquid for a system in which a helix inversion line crosses the chiral nematic to isotropic phase transition line are reported. While the chirality shows a strong temperature dependence in the chiral nematic phase, it loses all temperature dependence in the isotropic phase. In addition, the chirality in the isotropic phase is proportional to the chirality in the chiral nematic phase at the phase transition, and may in fact be continuous across the transition. While molecular field and phenomenological theories can explain the strong temperature dependence in the chiral nematic phase, including the helix inversion, these theories predict a strong discontinuity in the chirality at the phase transition that is not supported by experiment. So while a theory that includes short range molecular correlations is called for to understand the behavior of the chirality across the phase transition, theoretical attempts to explain the chirality of a phase from a microscopic level must account for the strong role played by long range orientational order.
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Affiliation(s)
- BP Huff
- Department of Physics and Astronomy, Swarthmore College, Pennsylvania 19081, USA
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Collings PJ. The Contributions of Horst Stegemeyer to Blue Phase Research. LIQUID CRYSTALS TODAY 1997. [DOI: 10.1080/13583149708047664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Longa L, Zelazna M, Trebin HR, Moscicki J. Electrostriction of the cubic blue phases in the presence of bond orientational order. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1996; 53:6067-6073. [PMID: 9964966 DOI: 10.1103/physreve.53.6067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Kutnjak Z, Garland CW, Schatz CG, Collings PJ, Booth CJ, Goodby JW. Critical point for the blue-phase-III-isotropic phase transition in chiral liquid crystals. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1996; 53:4955-4963. [PMID: 9964824 DOI: 10.1103/physreve.53.4955] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Longa L, Fink W, Trebin HR. Biaxiality of chiral liquid crystals. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1994; 50:3841-3852. [PMID: 9962438 DOI: 10.1103/physreve.50.3841] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Bowling MB, Collings PJ, Booth CJ, Goodby JW. Phase diagrams for the blue phases of highly chiral liquid crystals. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1993; 48:4113-4115. [PMID: 9961074 DOI: 10.1103/physreve.48.4113] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Longa L, Trebin HR. Bond orientational order in the blue phases of chiral liquid crystals. PHYSICAL REVIEW LETTERS 1993; 71:2757-2760. [PMID: 10054768 DOI: 10.1103/physrevlett.71.2757] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Longa L, Fink W, Trebin HR. Liquid-crystalline blue phase III and structures of broken icosahedral symmetry. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1993; 48:2296-2299. [PMID: 9960851 DOI: 10.1103/physreve.48.2296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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