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Oropesa WGC, Nascimento ES, Vieira AP. Mean-field model for a mixture of biaxial nematogens and dipolar nanoparticles. Phys Rev E 2024; 109:054701. [PMID: 38907419 DOI: 10.1103/physreve.109.054701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 03/27/2024] [Indexed: 06/24/2024]
Abstract
We analyze a mean-field model for mixtures involving biaxial nematogens and dipolar nanoparticles, taking into account not only orientational and isotropic pair interactions between nematogens but also orientational nematogen-nanoparticle interactions. We determine bulk equilibrium phase diagrams for a wide range of interaction strengths, identifying in each case the effect of the nanoparticles on the stability of nematic phases and on the appearance of multicritical points. Special attention is given to the limit of a low concentration of nanoparticles, in which their effect on the temperatures of both the first-order uniaxial-isotropic and the continuous biaxial-uniaxial transitions is investigated in detail.
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Affiliation(s)
- William G C Oropesa
- Universidade de São Paulo, Instituto de Fisica, Rua do Matao, 1371, 05508-090 São Paulo, SP, Brazil
- ICTP South American Institute for Fundamental Research, Instituto de Física Teórica, UNESP-Universidade Estadual Paulista, Rua Doutor Bento Teobaldo Ferraz 271, 01140-070 São Paulo, SP, Brazil
| | - Eduardo S Nascimento
- Departamento de Física, PUC-Rio, Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, Rio de Janeiro, Brazil
| | - André P Vieira
- Universidade de São Paulo, Instituto de Fisica, Rua do Matao, 1371, 05508-090 São Paulo, SP, Brazil
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2
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Drozd-Rzoska A, Łoś J, Rzoska SJ. The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4'-butylaniline with Transverse Permanent Dipole Moment and BaTiO 3 Nanoparticles. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:655. [PMID: 38668149 PMCID: PMC11053839 DOI: 10.3390/nano14080655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/03/2024] [Accepted: 04/07/2024] [Indexed: 04/29/2024]
Abstract
The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO3 nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4'-butylaniline) is a liquid crystalline compound with a permanent dipole moment transverse to the long molecular axis. The distortions-sensitive analysis of the dielectric constant revealed its hidden pretransitional anomaly, strongly influenced by the addition of nanoparticles. The evolution of the dielectric constant in the nematic phase shows the split into two regions, with the crossover coinciding with the standard melting temperature. The 'universal' exponential-type behavior of the low-frequency contribution to the real part of the dielectric permittivity is found. The critical-like pretransitional behavior in the solid phase is also evidenced. This is explained by linking the Lipovsky model to the Mossotti catastrophe concept under quasi-negative pressure conditions. The explicit preference for the 'critical-like' evolution of the apparent activation enthalpy is worth stressing for dynamics. Finally, the long-range, 'critical-like' behavior of the dissipation factor (D = tgδ), covering the isotropic liquid and nematic phases, is shown.
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Affiliation(s)
| | | | - Sylwester J. Rzoska
- Institute of High Pressure Physics, Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland; (A.D.-R.); (J.Ł.)
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3
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Hadjichristov GB. Control of Coherent Light through Microperiodic Director Modulation in Nematic Films under Low-Voltage DC Electric Field. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6014. [PMID: 37687708 PMCID: PMC10488426 DOI: 10.3390/ma16176014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/12/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023]
Abstract
This work addresses the achievement of efficient control of laser light transmission through stationary microperiodic parallel stripe textures formed in films of nematic liquid crystals (NLCs) in planar-oriented cells upon a direct-current (DC) electric field. By varying the field intensity and, thereby, the field-induced periodic modulation of the nematic director and hence the complex transmittance function corresponding to the longitudinal domain texture induced in NLC films with initial planar alignment, the intensity of a linearly polarized laser beam passed through the films can be well controlled. In 25 µm-thick films of room-temperature NLCs pentylcyanobiphenyl (5CB), this results in a low-voltage (~4 V) sharp and deep V-shaped behavior of their electro-optically controlled transmittance. Such a reversible electro-optical effect is interesting for active control of laser beam intensity and other applications. The relevant physical mechanism is analyzed and explained.
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Affiliation(s)
- Georgi B Hadjichristov
- Laboratory of Optics and Spectroscopy, Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
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4
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Khodaee M, Dalir N, Feghhi F, Ansari N, Mohammadimasoudi M, Goudarzi A, Nasiri AF, Kolahdouz M, Mohseni SM. Enhancement in electrical conductivity of liquid crystals by graphene metal oxide composites. Sci Rep 2023; 13:11688. [PMID: 37468686 DOI: 10.1038/s41598-023-38157-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 07/04/2023] [Indexed: 07/21/2023] Open
Abstract
Enhancing the electrical conductivity of liquid crystal (LC) circumvents challenges for application in advanced electronic components. Toward this, using additives made of different nanostructures that could result in functional LCs is suggested. In this paper, various concentrations of graphene (Gr)/metal-oxide (Fe3O4) nanocomposite (GMN) (0.0001-1 w%) were added to E7 nematic LC. We found that the role of anisotropic Gr flakes, their edges as well as surface-decorated-metal-oxide-additives have significant impact on electrical properties of E7. A range of appropriate additives of such a nanocomposite enhances the electrical conductivity of LCs. This effect can be traced through the decrease in the formation of GMN aggregates in the E7 and increase in the electrostatic field at the edges of the Gr sheets. Moreover, the presence of metal-oxide nanoclusters due to the presence of oxygen vacancies and defects facilitates the construction of conductive network for improving the charge transfer pathways and contributes to a stronger interaction of the Gr surface with charged species. These factors can provide Gr layers as dipole moments and lead to signal propagation in the dielectric medium. Our finding conveys a pathway toward significant enhancement of electrical conductivity in the LC family which can be useful for functional applications.
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Affiliation(s)
- M Khodaee
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, 1439957131, Iran
| | - N Dalir
- Department of Renewable Energy, Interdisciplinary Science and Technology, Tarbiat Modares University, Tehran, 14115-175, Iran
| | - F Feghhi
- Department of Physics, Alzahra University, Tehran, 19938, Iran
| | - N Ansari
- Department of Physics, Alzahra University, Tehran, 19938, Iran
| | - M Mohammadimasoudi
- Nano-Bio-Photonics Lab, Faculty of New Sciences and Technologies, University of Tehran, Tehran, 1439957131, Iran
| | - A Goudarzi
- Nano-Bio-Photonics Lab, Faculty of New Sciences and Technologies, University of Tehran, Tehran, 1439957131, Iran
| | - A F Nasiri
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, 1439957131, Iran
| | - M Kolahdouz
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, 1439957131, Iran.
| | - S M Mohseni
- Department of Physics, Shahid Beheshti University, Evin, Tehran, 19839, Iran.
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5
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Metal oxide alumina nanowire-induced polymer-dispersed liquid crystal composites for low power consumption and smart windows. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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6
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Barrera A, Binet C, Dubois F, Hébert PA, Supiot P, Foissac C, Maschke U. Temperature and frequency dependence on dielectric permittivity and electrical conductivity of recycled Liquid Crystals. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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7
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Chauhan G, Malik P, Deep A. Morphological, dielectric, electro-optic and photoluminescence properties of titanium oxide nanoparticles enriched polymer stabilized cholesteric liquid crystal composites. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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8
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Basu R, Gess DT. Ion trapping, reduced rotational viscosity, and accelerated electro-optic response characteristics in gold nano-urchin-nematic suspensions. Phys Rev E 2023; 107:024705. [PMID: 36932578 DOI: 10.1103/physreve.107.024705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
The free-ion concentration in a nematic liquid crystal (LC) is found to be significantly reduced when gold nano-urchins (AuNUs) of 50-nm diameter are dispersed in the LC in dilute concentrations. The nano-urchins on AuNUs trap a significant amount of mobile ions, reducing the free-ion concentration in the LC media. The reduction of free ions results in a decreased rotational viscosity and accelerated electro-optic response of the LC. The study is carried out with several AuNUs concentrations in the LC, and the experimental results consistently suggest that there exists an optimal concentration of AuNUs, above which they tend to aggregate. At the optimal concentration, the ion trapping is maximum, rotational viscosity is at its lowest, and the electro-optic response is the fastest. Above this optimal AuNUs concentration, the rotational viscosity is found to increase, and consequently, the LC no longer exhibits an accelerated electro-optic response.
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Affiliation(s)
- Rajratan Basu
- Department of Physics, Soft Matter and Nanomaterials Laboratory, The United States Naval Academy, Annapolis, Maryland 21402, USA
| | - Derek T Gess
- Department of Physics, Soft Matter and Nanomaterials Laboratory, The United States Naval Academy, Annapolis, Maryland 21402, USA
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9
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Fall S, Wang J, Regrettier T, Brouckaert N, Ibraikulov OA, Leclerc N, Lin Y, Elhaj MI, Komitov L, Lévêque P, Zhong Y, Brinkmann M, Kaczmarek M, Heiser T. Self-Powered Dynamic Glazing Based on Nematic Liquid Crystals and Organic Photovoltaic Layers for Smart Window Applications. ACS APPLIED MATERIALS & INTERFACES 2023; 15:4267-4274. [PMID: 36630212 DOI: 10.1021/acsami.2c21727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Dynamic windows allow monitoring of in-door solar radiation and thus improve user comfort and energy efficiency in buildings and vehicles. Existing technologies are, however, hampered by limitations in switching speed, energy efficiency, user control, or production costs. Here, we introduce a new concept for self-powered switchable glazing that combines a nematic liquid crystal, as an electro-optic active layer, with an organic photovoltaic material. The latter aligns the liquid crystal molecules and generates, under illumination, an electric field that changes the molecular orientation and thereby the device transmittance in the visible and near-infrared region. Small-area devices can be switched from clear to dark in hundreds of milliseconds without an external power supply. The drop in transmittance can be adjusted using a variable resistor and is shown to be reversible and stable for more than 5 h. First solution-processed large-area (15 cm2) devices are presented, and prospects for smart window applications are discussed.
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Affiliation(s)
- Sadiara Fall
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
| | - Jing Wang
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
| | - Thomas Regrettier
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
- Voltec Solar, 1 Rue des Prés, Dinsheim-sur-Bruche 67190, France
| | - Nicolas Brouckaert
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
- University of Southampton, Southampton SO17 1BJ, U.K
| | - Olzhas A Ibraikulov
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
| | - Nicolas Leclerc
- Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé, Université de Strasbourg, Centre National de la Recherche Scientifique, 25, Rue Becquerel, Strasbourg Cedex 67085, France
| | - Yaochen Lin
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
| | | | - Lachezar Komitov
- HighVistec GmbH, Benkenstrasse 254C, Witterswil CH 4108, Switzerland
- Dept. of Physics, University of Gothenburg, Gothenburg 41296, Sweden
- Department of Chemistry, CHRIST (Deemed to be University), Bangalore 560029, India
| | - Patrick Lévêque
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
| | - Yuhan Zhong
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
- Institut Charles Sadron, CNRS-UPR 22, 23 Rue du Loess, Strasbourg Cedex 2 67034, France
| | - Martin Brinkmann
- Institut Charles Sadron, CNRS-UPR 22, 23 Rue du Loess, Strasbourg Cedex 2 67034, France
| | | | - Thomas Heiser
- Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (ICube Research Institute), Université de Strasbourg, Centre National de la Recherche Scientifique, 23, Rue du Loess, Strasbourg Cedex 2 67037, France
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10
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Zhang R, Zhang Z, Han J, Yang L, Li J, Song Z, Wang T, Zhu J. Advanced liquid crystal-based switchable optical devices for light protection applications: principles and strategies. LIGHT, SCIENCE & APPLICATIONS 2023; 12:11. [PMID: 36593244 PMCID: PMC9807646 DOI: 10.1038/s41377-022-01032-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/18/2022] [Accepted: 11/01/2022] [Indexed: 05/14/2023]
Abstract
With the development of optical technologies, transparent materials that provide protection from light have received considerable attention from scholars. As important channels for external light, windows play a vital role in the regulation of light in buildings, vehicles, and aircrafts. There is a need for windows with switchable optical properties to prevent or attenuate damage or interference to the human eye and light-sensitive instruments by inappropriate optical radiation. In this context, liquid crystals (LCs), owing to their rich responsiveness and unique optical properties, have been considered among the best candidates for advanced light protection materials. In this review, we provide an overview of advances in research on LC-based methods for protection against light. First, we introduce the characteristics of different light sources and their protection requirements. Second, we introduce several classes of light modulation principles based on liquid crystal materials and demonstrate the feasibility of using them for light protection. In addition, we discuss current light protection strategies based on liquid crystal materials for different applications. Finally, we discuss the problems and shortcomings of current strategies. We propose several suggestions for the development of liquid crystal materials in the field of light protection.
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Affiliation(s)
- Ruicong Zhang
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150080, China
| | - Zhibo Zhang
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150080, China
| | - Jiecai Han
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150080, China
| | - Lei Yang
- Research Center of Analysis and Measurement, Harbin Institute of Technology, Harbin, 150080, China
| | - Jiajun Li
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150080, China
| | - Zicheng Song
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150080, China
| | - Tianyu Wang
- School of Energy Science & Engineering, Harbin Institute of Technology, Harbin, 150001, China.
| | - Jiaqi Zhu
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150080, China.
- Key Laboratory of Micro-systems and Micro-structures Manufacturing, Ministry of Education, Harbin, 150080, China.
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11
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Mesomorphism, Dielectric Permittivity, and Ionic Conductivity of Cholesterol Tridecylate Doped with Few-Layer Graphite Fragments. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.121139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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12
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Anu, Varshney D, Yadav K, Prakash J, Meena H, Singh G. Tunable dielectric and memory features of ferroelectric layered perovskite Bi4Ti3O12 nanoparticles doped nematic liquid crystal composite. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Functionalized and non-functionalized Multi Walled Carbon Nanotubes in the anisotropic media of liquid crystalline material. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Salah MB, Nasri R, Alharbi AN, Althagafi TM, Soltani T. Thermotropic liquid crystal doped with ferroelectric nanoparticles: Electrical behavior and ion trapping phenomenon. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119142] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Kaur G, Khushboo, Malik P. Mesomorphic, electro-optic and dielectric behavior of self-assembled nanocomposite materials: Nematic mixture doped with carbon coated cobalt nanoparticles. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Varshney D, Anu, Prakash J, Pratap Singh V, Yadav K, Singh G. Probing the impact of bismuth-titanate based nanocomposite on the dielectric and electro-optical features of a nematic liquid crystal material. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118389] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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17
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Periodic Electro-Optical Characteristics of PDLC Film Driven by a Low-Frequency Square Wave Voltage. CRYSTALS 2022. [DOI: 10.3390/cryst12020163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The electro-optical features of the PDLC films applied with a low-frequency square wave voltage were investigated. The transmittance curves indicated the double frequency of the applied voltage at 0–50 Hz, which resulted from the relaxation of an internal electric field polarized by ions in LC droplets. When the local electric field was reversed, the internal polarization electric field could be maintained and superimposed on the local electric field. The relaxation of the internal polarized electric field resulted in the relaxation of the transmittance. Furthermore, the transmittance curves changed with the frequency of the applied voltage.
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Rani A, Chakraborty S, Sinha A. Effect of CdSe/ZnS quantum dots doping on the ion transport behavior in nematic liquid crystal. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117327] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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19
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Dalir N, Javadian S. Thermodynamic study for the role of functional group on the honey-comb pattern interaction between CNT and E5CN7 nematic liquid crystal. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117287] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Barrera A, Binet C, Dubois F, Hébert PA, Supiot P, Foissac C, Maschke U. Dielectric Spectroscopy Analysis of Liquid Crystals Recovered from End-of-Life Liquid Crystal Displays. Molecules 2021; 26:molecules26102873. [PMID: 34066236 PMCID: PMC8150612 DOI: 10.3390/molecules26102873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 11/24/2022] Open
Abstract
In the present work, the dielectric properties of recycled liquid crystals (LCs) (non-purified, purified, and doped with diamond nanoparticles at 0.05, 0.1, and 0.2 wt%) were investigated. The studied LC mixtures were obtained from industrial recycling of end-of-life LC displays presenting mainly nematic phases. Dielectric measurements were carried out at room temperature on a frequency range from 0.1 to 106 Hz using an impedance analyzer. The amplitude of the oscillating voltage was fixed at 1 V using cells with homogeneous and homeotropic alignments. Results show that the dielectric anisotropy of all purified samples presents positive values and decreases after the addition of diamond nanoparticles to the LC mixtures. DC conductivity values were obtained by applying the universal law of dielectric response proposed by Jonscher. In addition, conductivity of the doped LC mixtures is lower than that of the undoped and non-purified LC.
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Affiliation(s)
- Ana Barrera
- CNRS, INRAE, Centrale Lille, UMR 8207—UMET—Unité Matériaux et Transformations, Université de Lille, F-59000 Lille, France; (A.B.); (C.B.); (P.S.); (C.F.)
| | - Corinne Binet
- CNRS, INRAE, Centrale Lille, UMR 8207—UMET—Unité Matériaux et Transformations, Université de Lille, F-59000 Lille, France; (A.B.); (C.B.); (P.S.); (C.F.)
| | - Frédéric Dubois
- UR 4476, UDSMM, Unité de Dynamique et Structure des Matériaux Moléculaires, Université du Littoral Côte d’Opale, 59 379 Dunkerque, France;
| | - Pierre-Alexandre Hébert
- UR 4491, LISIC, Laboratoire d’Informatique Signal et Image de la Côte d’Opale, Université du Littoral Côte d’Opale, 59 379 Dunkerque, France;
| | - Philippe Supiot
- CNRS, INRAE, Centrale Lille, UMR 8207—UMET—Unité Matériaux et Transformations, Université de Lille, F-59000 Lille, France; (A.B.); (C.B.); (P.S.); (C.F.)
| | - Corinne Foissac
- CNRS, INRAE, Centrale Lille, UMR 8207—UMET—Unité Matériaux et Transformations, Université de Lille, F-59000 Lille, France; (A.B.); (C.B.); (P.S.); (C.F.)
| | - Ulrich Maschke
- CNRS, INRAE, Centrale Lille, UMR 8207—UMET—Unité Matériaux et Transformations, Université de Lille, F-59000 Lille, France; (A.B.); (C.B.); (P.S.); (C.F.)
- Correspondence: ; Tel.: +33-3-20-33-63-81
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21
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Effect of γ-irradiation on various important physical properties of a room temperature ferroelectric liquid crystal mixture and its silver nanocomposite. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115628] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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22
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Garbovskiy Y. Conventional and unconventional ionic phenomena in tunable soft materials made of liquid crystals and nanoparticles. NANO EXPRESS 2021. [DOI: 10.1088/2632-959x/abe652] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
A great variety of tunable multifunctional materials can be produced by combining nanoparticles and liquid crystals. Typically, the tunability of such soft nanocomposites is achieved via external electric fields resulting in the field-induced reorientation of liquid crystals. This reorientation can be altered by ions normally present in liquid crystals in small quantities. In addition, nanomaterials dispersed in liquid crystals can also affect the behavior of ions. Therefore, an understanding of ionic phenomena in liquid crystals doped with nanoparticles is essential for future advances in liquid crystal-aided nanoscience and nanotechnology. This paper provides an overview of the ionic effects observed in liquid crystals doped with nanomaterials. An introduction to liquid crystals is followed by a brief overview of nanomaterials in liquid crystals. After giving a basic description of ions in liquid crystals and experimental methods to measure them, a wide range of ionic phenomena in liquid crystals doped with different types of nanomaterials is discussed. After that, both existing and emerging applications of tunable soft materials made of liquid crystals and nanodopants are presented with an emphasis on the role of ionic effects in such systems. Finally, the discussion of unsolved problems and future research directions completes the review.
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Enhanced electrochemical and electro-optical properties of nematic liquid crystal doped with Ni:ZnCdS/ZnS core/shell quantum dots. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114373] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Debnath A, Mandal PK, Sarma A, Gutowski O. Effect of silver nanoparticle doping on the physicochemical properties of a room temperature ferroelectric liquid crystal mixture. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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25
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Mrukiewicz M, Perkowski P, Urbańska M, Węgłowska D, Piecek W. Electrical conductivity of ion-doped fluoro substituted liquid crystal compounds for application in the dynamic light scattering effect. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113810] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Chaudhary A, Malik P, Shukla R, Mehra R, Raina K. Role of SiO2 optically active mediators to tailor optical and electro-optical properties of ferroelectric liquid crystalline nanocomposites. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Lalik S, Deptuch A, Jaworska-Goła B T, Fryń P, Dardas D, Stefańczyk O, Urbańska M, Marzec M. Modification of AFLC Physical Properties by Doping with BaTiO 3 Particles. J Phys Chem B 2020; 124:6055-6073. [PMID: 32569472 DOI: 10.1021/acs.jpcb.0c02401] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, for the first time, the influence of the BaTiO3 particles on the antiferroelectric liquid crystalline phase was shown. Low concentrations and two different sizes of BaTiO3 particles (nano- and submicroparticles) were used. It was found that admixture of the ferroelectric particles causes a decrease in the concentration of free ions in the liquid crystal matrix. Despite the small amount of admixture, a decrease in spontaneous polarization, switching time and rotational viscosity, was observed, while the tilt angle of molecules and the smectic layer thickness did not change. It turns out that BaTiO3 particles have a very large impact on the dielectric spectra not only in the antiferroelectric phase but also in the ferroelectric and paraelectric phases of the polymorphic mixture studied. The dopants affect also the complex conductivity. In this paper, we explain why some properties are modified by BaTiO3 particles and others are not.
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Affiliation(s)
- Sebastian Lalik
- Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków, Poland
| | - Aleksandra Deptuch
- Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków, Poland.,Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland
| | | | - Patryk Fryń
- Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków, Poland
| | - Dorota Dardas
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Olaf Stefańczyk
- Department of Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Magdalena Urbańska
- Institute of Chemistry, Military University of Technology, Kaliskiego 2, 00-908, Warszawa, Poland
| | - Monika Marzec
- Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków, Poland
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28
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Chausov DN, Kurilov AD, Kucherov RN, Simakin AV, Gudkov SV. Electro-optical performance of nematic liquid crystals doped with gold nanoparticles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:395102. [PMID: 32454469 DOI: 10.1088/1361-648x/ab966c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/26/2020] [Indexed: 06/11/2023]
Abstract
The effect of gold nanoparticles on the dielectric, electro-optical, and rheological properties of the ZhK-1289 liquid-crystal mixture that define the response time of liquid-crystal devices with a concentration range of 0.06-5 wt% was investigated in this study. A phase diagram of the obtained composites was formed demonstrating an increase in the clearing temperature and a broadening of the mesophase existence range in the case of doping nanoparticles. It was found that in the obtained dispersions there are structural rearrangements in the low concentration range leading to an increase in the lateral bending stiffness of the liquid-crystal matrix, a decrease in the response time and threshold voltage of the Freedericksz transition, and also an increase in the anisotropy of the dielectric permittivity and the refraction index. The improvement of the electro-optical performance of the liquid crystal can be caused by the nanoparticle adsorption of impurity ions, which reduces the field-screening effect in the liquid crystal. According to the results obtained in this study, the optimal values of the physical parameters of liquid-crystal composites doped with gold nanoparticles for their application in practice are achieved in a concentration range of 0.5-1 wt%.
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Affiliation(s)
- D N Chausov
- Moscow Region State University, 24 Very Voloshinoy St., Mytishchi, 141014, Russia
| | - A D Kurilov
- Moscow Region State University, 24 Very Voloshinoy St., Mytishchi, 141014, Russia
| | - R N Kucherov
- Moscow Region State University, 24 Very Voloshinoy St., Mytishchi, 141014, Russia
| | - A V Simakin
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilova St., Moscow, 119991, Russia
| | - S V Gudkov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilova St., Moscow, 119991, Russia
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29
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Shen Y, Dierking I. Dynamic dissipative solitons in nematics with positive anisotropies. SOFT MATTER 2020; 16:5325-5333. [PMID: 32469028 DOI: 10.1039/d0sm00676a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electric field induced instabilities of nematic molecules are of importance for both fundamental science and practical applications. Complex electro-hydrodynamic (EHD) effects such as electro-convection, fingerprint textures, spatiotemporal chaos, and solitons in nematics have been broadly investigated and generated much attention. In this work, dissipative solitons as a novel EHD phenomenon are realized in nematics with positive anisotropies, presumably for the first time. Unlike the ones reported recently in nematics with negative anisotropies whose formation and dynamics are mainly attributed to the flexoelectric and electro-convection effects, the solitons discussed here arise from the nonlinear coupling between the director field and the isotropic flow induced by ion motion. The structure and dynamics of the solitons are demonstrated and the influences of chirality, azimuthal anchoring and ion concentration are also investigated. Finally, we show that the propagation trajectory of solitons can be manipulated by patterned photoalignment and micro-particles can be trapped by them as vehicles for micro-cargo transport.
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Affiliation(s)
- Yuan Shen
- Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Ingo Dierking
- Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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30
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On the Analogy between Electrolytes and Ion-Generating Nanomaterials in Liquid Crystals. NANOMATERIALS 2020; 10:nano10030403. [PMID: 32106491 PMCID: PMC7152844 DOI: 10.3390/nano10030403] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/20/2022]
Abstract
Nanomaterials in liquid crystals are a hot topic of contemporary liquid crystal research. An understanding of the possible effects of nanodopants on the properties of liquid crystals is critical for the development of novel mesogenic materials with improved functionalities. This paper focuses on the electrical behavior of contaminated nanoparticles in liquid crystals. More specifically, an analogy between electrolytes and ion-generating nanomaterials in liquid crystals is established. The physical consequences of this analogy are analyzed. Under comparable conditions, the number of ions generated by nanomaterials in liquid crystals can be substantially greater than the number of ions generated by electrolytes of similar concentration.
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31
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Prakash J, Khan S, Chauhan S, Biradar A. Metal oxide-nanoparticles and liquid crystal composites: A review of recent progress. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.112052] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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32
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Cirtoaje C, Petrescu E. The Influence of Single-Walled Carbon Nanotubes on the Dynamic Properties of Nematic Liquid Crystals in Magnetic Field. MATERIALS (BASEL, SWITZERLAND) 2019; 12:E4031. [PMID: 31817251 PMCID: PMC6947598 DOI: 10.3390/ma12244031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 11/27/2019] [Accepted: 11/29/2019] [Indexed: 11/23/2022]
Abstract
This article aims to study the impact of carbon nanotube dispersions in liquid crystals. A theoretical model for the system's dynamics is presented, considering the elastic continuum theory and a planar alignment of liquid crystal molecules on the nanotube's surface. Experimental calculation of the relaxation times in the magnetic field was made for two cases: when the field was switched on (τon), and when it was switched off (τoff). The results indicate an increase of the relaxation time by about 25% when the magnetic field was switched off, and a smaller increase (about 10%) when the field was switched on, where both were in good agreement with the theoretical values.
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Affiliation(s)
| | - Emil Petrescu
- Department of Physics, Faculty of Applied Science, University Politehnica of Bucharest, Bucharest RO-060042, Romania;
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33
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Evolution of morphology and electrochemical properties of colloidal nematic liquid crystal doped with carbon nanotubes and magnetite. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.110927] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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34
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Abstract
Liquid Crystals (LCs) are widely used in display devices, electro-optic modulators, and optical switches. A field-induced electrical conductivity modulation in pure liquid crystals is very low which makes it less preferable for direct current (DC) and radio-frequency (RF) switching applications. According to the literature, a conductivity enhancement is possible by nanoparticle doping. Considering this aspect, we reviewed published works focused on an electric field-induced conductivity modulation in carbon nanotube-doped liquid crystal composites (LC-CNT composites). A two to four order of magnitude switching in electrical conductivity is observed by several groups. Both in-plane and out-of-plane device configurations are used. In plane configurations are preferable for micro-device fabrication. In this review article, we discussed published works reporting the elastic and molecular interaction of a carbon nanotube (CNT) with LC molecules, temperature and CNT concentration effects on electrical conductivity, local heating, and phase transition behavior during switching. Reversibility and switching speed are the two most important performance parameters of a switching device. It was found that dual frequency nematic liquid crystals (DFNLC) show a faster switching with a good reversibility, but the switching ratio is only two order of magnitudes. A better way to ensure reversibility with a large switching magnitude is to use two pairs of in-plane electrodes in a cross configuration. For completeness and comparison purposes, we briefly reviewed other nanoparticle- (i.e., Au and Ag) doped LC composite’s conductivity behavior as well. Finally, based on the reported works reviewed in this article on field induced conductivity modulation, we proposed a novel idea of RF switching by LC composite materials. To support the idea, we simulated an LC composite-based RF device considering a simple analytical model. Our RF analysis suggests that a device made with an LC-CNT composite could show an acceptable performance. Several technological challenges needed to be addressed for a physical realization and are also discussed briefly.
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35
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Improvement of Electro-Optical Properties of PSLC Devices by Silver Nanowire Doping. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9010145] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Polymer stabilized liquid crystal (PSLC) devices modulating the light that goes through them have broad applications. In this study, to improve the electro-optical properties of a PSLC device, Ag nanowires with diameter about 20 nm were doped into PSLC active layer with different concentrations. The influence of Ag nanowires concentration on the driving voltage, on-state response time and frequency modulation characteristics of a PSLC device were studied. The results indicate that the doping of Ag nanowires can reduce the driving voltage of PSLC cell up to 42%. The response time of the PSLC cell can decrease by about 41%. Meanwhile, frequency modulation does not show significant improvement upon Ag nanowire doping. Overall, Ag nanowire doping can improve the electro-optical properties of PSLC device effectively.
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36
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Nafees A, Kalita G, Sinha A. Effect of titanium dioxide nanoparticles on the dielectric and electro-optical properties of bent-core liquid crystals. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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37
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Cetinkaya M, Yildiz S, Ozbek H. The effect of -COOH functionalized carbon nanotube doping on electro-optical, thermo-optical and elastic properties of a highly polar smectic liquid crystal. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.10.078] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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38
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Enhancement of Image Quality in LCD by Doping γ-Fe₂O₃ Nanoparticles and Reducing Friction Torque Difference. NANOMATERIALS 2018; 8:nano8110911. [PMID: 30404171 PMCID: PMC6267559 DOI: 10.3390/nano8110911] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 11/02/2018] [Accepted: 11/04/2018] [Indexed: 01/24/2023]
Abstract
Improving image sticking in liquid crystal display (LCD) has attracted tremendous interest because of its potential to enhance the quality of the display image. Here, we proposed a method to evaluate the residual direct current (DC) voltage by varying liquid crystal (LC) cell capacitance under the combined action of alternating current (AC) and DC signals. This method was then used to study the improvement of image sticking by doping γ-Fe2O3 nanoparticles into LC materials and adjusting the friction torque difference of the upper and lower substrates. Detailed analysis and comparison of residual characteristics for LC materials with different doping concentrations revealed that the LC material, added with 0.02 wt% γ-Fe2O3 nanoparticles, can absorb the majority of free ions stably, thereby reducing the residual DC voltage and extending the time to reach the saturated state. The physical properties of the LC materials were enhanced by the addition of a small amount of nanoparticles and the response time of doping 0.02 wt% γ-Fe2O3 nanoparticles was about 10% faster than that of pure LC. Furthermore, the lower absolute value of the friction torque difference between the upper and lower substrates contributed to the reduction of the residual DC voltage induced by ion adsorption in the LC cell under the same conditions. To promote the image quality of different display frames in the switching process, we added small amounts of the nanoparticles to the LC materials and controlled friction technology accurately to ensure the same torque. Both approaches were proven to be highly feasible.
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39
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Bulavin L, Lisetski L, Minenko S, Samoilov A, Klepko V, Bohvan S, Lebovka N. Microstructure and optical properties of nematic and cholesteric liquid crystals doped with organo-modified platelets. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2017.12.078] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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40
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Prodanov MF, Popova EV, Gamzaeva SA, Fedoryako AP, Vashchenko VV. Ferromagnetic nanoparticles in a ferroelectric liquid crystal: Properties of stable colloids in homogeneous cells. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2017.12.123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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41
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Agrahari K, Pathak G, Vimal T, Kurp K, Srivastava A, Manohar R. Dielectric and spectroscopic study of nano-sized diamond dispersed ferroelectric liquid crystal. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.05.097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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42
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Nanomaterials in Liquid Crystals as Ion-Generating and Ion-Capturing Objects. CRYSTALS 2018. [DOI: 10.3390/cryst8070264] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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43
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Kumar P, Debnath S, Rao NVS, Sinha A. Nanodoping: a route for enhancing electro-optic performance of bent core nematic system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:095101. [PMID: 29336349 DOI: 10.1088/1361-648x/aaa801] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the effect of dispersion of barium titanate (BaTiO3) nanoparticles (BNPs) in a four ring bent core nematic (BCN) liquid crystal. Polarizing optical microscopy reveals the presence of a single nematic phase in pure and doped states. Polar switching has been observed in the bent core system and the value of spontaneous polarization (P s) increases with increase in doping concentration of BNPs in BCN. Dielectric study shows a lower frequency mode, which can be ascribed to the formation of cybotactic clusters. These clusters are also responsible for the observed polar switching in pure, as well as, in doped BCNs. Another higher frequency mode, observed only in pure BCN, indicates the rotation of molecules about their long molecular axis. The conductivity of doped samples is also found to decrease as compared to the pure BCN. This reduction helps in the minimization of negative effects caused by free ions in liquid crystal based devices. This study demonstrates that the interaction between BNPs and BCN molecules improves the P s, dielectric behaviour, viscosity and reduces the conductivity of pure BCN. Hence, nanodoping in a BCN is an effective method for the enhancement of electro-optic performances and will lead to the development of faster electro-optic devices.
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Affiliation(s)
- Pradeep Kumar
- Department of Physics, Indian Institute of Technology Delhi, 110016, India
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44
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Theoretical studies of the influence of nanoparticle dopants on the ferroelectric properties of a ferroelectric liquid crystal. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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45
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Garbovskiy Y. Kinetics of Ion-Capturing/Ion-Releasing Processes in Liquid Crystal Devices Utilizing Contaminated Nanoparticles and Alignment Films. NANOMATERIALS 2018; 8:nano8020059. [PMID: 29360774 PMCID: PMC5853692 DOI: 10.3390/nano8020059] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 01/17/2018] [Accepted: 01/19/2018] [Indexed: 11/20/2022]
Abstract
Various types of nanomaterials and alignment layers are considered major components of the next generation of advanced liquid crystal devices. While the steady-state properties of ion-capturing/ion-releasing processes in liquid crystals doped with nanoparticles and sandwiched between alignment films are relatively well understood, the kinetics of these phenomena remains practically unexplored. In this paper, the time dependence of ion-capturing/ion-releasing processes in liquid crystal cells utilizing contaminated nanoparticles and alignment layers is analyzed. The ionic contamination of both nanodopants and alignment films governs the switching between ion-capturing and ion-releasing regimes. The time dependence (both monotonous and non-monotonous) of these processes is characterized by time constants originated from the presence of nanoparticles and films, respectively. These time constants depend on the ion adsorption/ion desorption parameters and can be tuned by changing the concentration of nanoparticles, their size, and the cell thickness.
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Affiliation(s)
- Yuriy Garbovskiy
- UCCS BioFrontiers Center and Department of Physics, University of Colorado Colorado Springs, Colorado Springs, CO 80918, USA.
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46
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Garbovskiy YA, Evans DR, Banerjee PP, Glushchenko A. Static and dynamic electro-optical properties of liquid crystals mediated by ferroelectric polymer films. RSC Adv 2018; 8:1889-1898. [PMID: 35542627 PMCID: PMC9077257 DOI: 10.1039/c7ra12443k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 12/23/2017] [Indexed: 11/21/2022] Open
Abstract
Liquid crystals (LC) can reveal the fractal dimension of multi-domain ferroelectric films (FF) while these films can control the switching time of FF–LC hybrids.
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Affiliation(s)
- Y. A. Garbovskiy
- UCCS BioFrontiers Center
- Department of Physics
- University of Colorado Colorado Springs
- Colorado Springs
- USA
| | - D. R. Evans
- Air Force Research Laboratory
- Materials and Manufacturing Directorate
- Wright Patterson Air Force Base
- USA
| | - P. P. Banerjee
- Electro-Optics and Photonics, and Electrical and Computer Engineering
- University of Dayton
- Dayton
- USA
| | - A. V. Glushchenko
- UCCS BioFrontiers Center
- Department of Physics
- University of Colorado Colorado Springs
- Colorado Springs
- USA
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47
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Garbovskiy Y, Glushchenko A. Ferroelectric Nanoparticles in Liquid Crystals: Recent Progress and Current Challenges. NANOMATERIALS 2017; 7:nano7110361. [PMID: 29104276 PMCID: PMC5707578 DOI: 10.3390/nano7110361] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 10/24/2017] [Accepted: 10/24/2017] [Indexed: 12/21/2022]
Abstract
The dispersion of ferroelectric nanomaterials in liquid crystals has recently emerged as a promising way for the design of advanced and tunable electro-optical materials. The goal of this paper is a broad overview of the current technology, basic physical properties, and applications of ferroelectric nanoparticle/liquid crystal colloids. By compiling a great variety of experimental data and discussing it in the framework of existing theoretical models, both scientific and technological challenges of this rapidly developing field of liquid crystal nanoscience are identified. They can be broadly categorized into the following groups: (i) the control of the size, shape, and the ferroelectricity of nanoparticles; (ii) the production of a stable and aggregate-free dispersion of relatively small (~10 nm) ferroelectric nanoparticles in liquid crystals; (iii) the selection of liquid crystal materials the most suitable for the dispersion of nanoparticles; (iv) the choice of appropriate experimental procedures and control measurements to characterize liquid crystals doped with ferroelectric nanoparticles; and (v) the development and/or modification of theoretical and computational models to account for the complexity of the system under study. Possible ways to overcome the identified challenges along with future research directions are also discussed.
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Affiliation(s)
- Yuriy Garbovskiy
- UCCS Biofrontiers Center and Department of Physics, University of Colorado Colorado Springs, Colorado Springs, CO 80918, USA.
| | - Anatoliy Glushchenko
- Department of Physics, University of Colorado Colorado Springs, Colorado Springs, CO 80918, USA.
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48
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Li H, Pan F, Wu Y, Zhang Y, Xie X. Improvement in imaging contrast feature of liquid crystal lens with the dopant of multi-walled carbon nanotubes. APPLIED OPTICS 2017; 56:6655-6662. [PMID: 29047958 DOI: 10.1364/ao.56.006655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
An effective method to fabricate a high-contrast imaging liquid crystal (LC) lens with a relatively fast response time is proposed. This electrically tunable-focus LC lens is doped with multi-walled carbon nanotubes (MWCNTs) and has a high-resistance layer. A grinding method is utilized to lower agglomeration of doping MWCNTs. With respect to the high-resistance layer, it can make maximum use of doped nanoparticles to behave with high-quality lens character. The principles of improvement in electro-optical properties are discussed. The experimental results show that the proposed LC lens is effectively improved. The LC lens has great potential in compact imaging systems.
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49
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Ions and size effects in nanoparticle/liquid crystal colloids sandwiched between two substrates. The case of two types of fully ionized species. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.04.075] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Tomylko S, Yaroshchuk O, Koval'chuk O, Lebovka N. Structural evolution and dielectric properties of suspensions of carbon nanotubes in nematic liquid crystals. Phys Chem Chem Phys 2017; 19:16456-16463. [PMID: 28608878 DOI: 10.1039/c7cp01722g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Structuring of carbon nanotubes (CNTs) in liquid crystals (LCs) and electro-physical characteristics of LC + CNT suspensions were studied in a very broad range of CNT concentrations, C, from 10-5 wt% (highly diluted suspensions) to 2.5 wt% (highly viscous suspensions). Along with the conventional sandwich cells with the transparent electrodes on the substrates, we used the cells with the in-plane applied electrical field in order to monitor changes of electrical parameters in the same direction as the structural changes observed under an optical microscope. The data revealed four stages of structural evolution with the increase of C: (1) dispersion of individual CNTs and their very small aggregates (C < 3 × 10-4 wt%), (2) presence of branched aggregates with a non-compact structure (C = 3 × 10-4-5 × 10-3 wt%), (3) percolation of non-compact aggregates (C = 5 × 10-3-10-1 wt%) and (4) compaction of aggregates and formation of a dense network (C = 10-1-1 wt%). In the studied concentration range, the conductivity displayed two percolation thresholds at C ≈ 0.004 wt% and C ≈ 0.5 wt%, which are associated with the formation of a non-compact and dense CNT network. By contrast, the permittivity ε' revealed only one percolation threshold at C ≈ 0.5 wt%, when the distance between the adjacent CNTs becomes incredibly small.
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Affiliation(s)
- S Tomylko
- Institute of Physics, NAS of Ukraine, Prospekt Nauky 46, 03028, Kyiv, Ukraine.
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