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Emelyanenko AV, Rudyak VY, Shvetsov SA, Araoka F, Nishikawa H, Ishikawa K. Emergence of paraelectric, improper antiferroelectric, and proper ferroelectric nematic phases in a liquid crystal composed of polar molecules. Phys Rev E 2022; 105:064701. [PMID: 35854528 DOI: 10.1103/physreve.105.064701] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 05/13/2022] [Indexed: 05/15/2023]
Abstract
We have elaborated a theoretical approach for the description of polar nematic phases observed by Nishikawa et al. [Adv. Mater. 29, 1702354 (2017)0935-964810.1002/adma.201702354], their structures, and transitions between them. Specific symmetry contributions to the pair molecular potentials provide the molecular mechanisms responsible for the formation of proper and improper polarity on the macroscopic level. An improper antiferroelectric nematic M2 phase can arise between paraelectric nematic M1 and proper ferroelectric nematic MP in the temperature scale. The local polarization in M2 arises mostly due to the local splay deformation. The director distribution in M2 represents the conjugation of cylindrical waves with opposite splay and polarization signs. The director and polarization are parallel to the cylindrical domain axes in the middle of each cylinder but exhibit considerable (mostly radial) deformation on the periphery of each cylinder. Polarization vectors are mostly stacked antiparallel on the borders between the domains without the director disruption. The domain size decreases with the decreasing temperature, the percentage of the antiferroelectric decouplings increases, and M2 exhibits the first-order phase transition into proper ferroelectric MP. With the increasing temperature the domain size in the M2 phase increases, the domination of particular polar orientation of molecules reduces, and finally, the domain size diverges at particular temperature corresponding to the second-order phase transition from M2 to paraelectric M1. Variations of the polar and nonpolar orientational order parameters are estimated within each phase and between the phases. Our experimental and computer simulation results (also presented in the paper) fully support our theoretical findings.
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Affiliation(s)
| | - V Yu Rudyak
- Lomonosov Moscow State University, Moscow 119991, Russia
| | - S A Shvetsov
- Lomonosov Moscow State University, Moscow 119991, Russia
- Lebedev Physical Institute, Moscow 119991, Russia
| | - F Araoka
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa Wako, Saitama 351-0198, Japan
| | - H Nishikawa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa Wako, Saitama 351-0198, Japan
| | - K Ishikawa
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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Śliwa I, Maslennikov PV, Zakharov AV. Anchoring transition induced by trans-cis isomerization in photosensitive substrate. Phys Rev E 2022; 105:014702. [PMID: 35193275 DOI: 10.1103/physreve.105.014702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 01/02/2022] [Indexed: 11/07/2022]
Abstract
A molecular model describing the effective anchoring energy of a liquid crystal (LC) system, composed of 4-n-pentyl-4^{'}-cyanobiphenyl (5CB) molecules deposited on a photosensitive azobenzene layer consisting of 6Az10PVA molecules, is proposed. This model takes into account the interaction between the surface polarization in the LC phase and the surface electric field, arising from the surface charge density. Within the framework of this molecular model, the mechanism responsible for the anchoring transition in the LC phase from homeotropic to planar alignment and vice versa, caused by trans-cis and cis-trans conformational changes in the monolayer 6Az10PVA after laser radiation, is described. It is shown that using experimental data for the voltage across the 6Az10PVA+5CB film, obtained by the surface potential technique, the charge separation during the conformational changing, caused by the laser irradiation, may lead to an anchoring transition induced by trans-cis-trans isomerization in the photosensitive azobenzene monolayer. The calculated values of the isothermal surface pressure diagram π-A showed that the surface area A per LC molecule is noticeably higher for the cis configuration, which reflects a less efficient packaging than in the trans state.
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Affiliation(s)
- Izabela Śliwa
- Poznan University of Economics and Business, Al. Niepodleglosci 10, 61-875 Poznan, Poland
| | - Pavel V Maslennikov
- Immanuel Kant Baltic Federal University, Universitetskaya Street 2, Kaliningrad 236040, Russia
| | - Alex V Zakharov
- Saint Petersburg Institute for Machine Sciences, Russian Academy of Sciences, Saint Petersburg 199178, Russia
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Kostikov DA, Krakhalev MN, Prishchepa OO, Zyryanov VY. Nematic Structures under Conical Anchoring at Various Director Tilt Angles Specified by Polymethacrylate Compositions. Polymers (Basel) 2021; 13:polym13172993. [PMID: 34503033 PMCID: PMC8434558 DOI: 10.3390/polym13172993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 11/24/2022] Open
Abstract
Dependence of the director tilt angle of nematic liquid crystal (LC) under conical anchoring from the two-component polymer mixture composition has been studied. We varied the ratio of poly(isobutyl methacrylate) (PiBMA), which specifies a conical anchoring for the nematic liquid crystal LN-396, and poly(methylmethacrylate) (PMMA) assigning a tangential alignment for the same nematic. An oblique incidence light technique to determine a tilt angle has been used. It has been shown that the tilt angle increases from 0∘ to 47.7∘ when PiBMA:PMMA ratio changes in the range 30:70 to 100:0. The specific optical textures viewed under the polarizing microscope and proper orientational structures have been considered for various compositions of the polymer films. An electric field action on the formed orientational structures has been investigated. The obtained results are promising for the application in various electro-optical LC devices with a conical anchoring in which the director tilt angle is a crucial parameter: a controlled diffraction gratings, an electrically operated achromatic rotators of linear light polarization, etc.
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Affiliation(s)
- Denis A. Kostikov
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia; (M.N.K.); (O.O.P.); (V.Y.Z.)
- Institute of Engineering Physics and Radio Electronics, Siberian Federal University, 660041 Krasnoyarsk, Russia
- Correspondence:
| | - Mikhail N. Krakhalev
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia; (M.N.K.); (O.O.P.); (V.Y.Z.)
- Institute of Engineering Physics and Radio Electronics, Siberian Federal University, 660041 Krasnoyarsk, Russia
| | - Oxana O. Prishchepa
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia; (M.N.K.); (O.O.P.); (V.Y.Z.)
| | - Victor Ya. Zyryanov
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia; (M.N.K.); (O.O.P.); (V.Y.Z.)
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Shvetsov SA, Rudyak VY, Gruzdenko AA, Emelyanenko AV. Axisymmetric skyrmion-like structures in spherical-cap droplets of chiral nematic liquid crystal. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Esteves C, Ramou E, Porteira ARP, Barbosa AJM, Roque ACA. Seeing the Unseen: The Role of Liquid Crystals in Gas-Sensing Technologies. ADVANCED OPTICAL MATERIALS 2020; 8:1902117. [PMID: 32612901 PMCID: PMC7329384 DOI: 10.1002/adom.201902117] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 02/17/2020] [Indexed: 05/17/2023]
Abstract
Fast, real-time detection of gases and volatile organic compounds (VOCs) is an emerging research field relevant to most aspects of modern society, from households to health facilities, industrial units, and military environments. Sensor features such as high sensitivity, selectivity, fast response, and low energy consumption are essential. Liquid crystal (LC)-based sensors fulfill these requirements due to their chemical diversity, inherent self-assembly potential, and reversible molecular order, resulting in tunable stimuliresponsive soft materials. Sensing platforms utilizing thermotropic uniaxial systems-nematic and smectic-that exploit not only interfacial phenomena, but also changes in the LC bulk, are demonstrated. Special focus is given to the different interaction mechanisms and tuned selectivity toward gas and VOC analytes. Furthermore, the different experimental methods used to transduce the presence of chemical analytes into macroscopic signals are discussed and detailed examples are provided. Future perspectives and trends in the field, in particular the opportunities for LC-based advanced materials in artificial olfaction, are also discussed.
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Affiliation(s)
- Carina Esteves
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Efthymia Ramou
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Ana Raquel Pina Porteira
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Arménio Jorge Moura Barbosa
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Ana Cecília Afonso Roque
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
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Krakhalev MN, Rudyak VY, Prishchepa OO, Gardymova AP, Emelyanenko AV, Liu JH, Zyryanov VY. Orientational structures in cholesteric droplets with homeotropic surface anchoring. SOFT MATTER 2019; 15:5554-5561. [PMID: 31243424 DOI: 10.1039/c9sm00384c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The dependency of orientational structures in cholesteric droplets with homeotropic surface anchoring on the helicity parameter has been studied by experiment and simulations. We have observed a sequence of structures, in which the director configurations and topological defects were identified by comparison of polarized microscopy pictures with simulated textures. A toron-like and low-symmetry intermediate layer-like structures have been revealed and studied in detail. The ranges of stability of the observed structures have been summarized in a general diagram and explained by the helicity parameter dependence of the free energy terms.
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Affiliation(s)
- Mikhail N Krakhalev
- Kirensky Institute of Physics, Federal Research Center - Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russia and Institute of Engineering Physics and Radio Electronics, Siberian Federal University, Krasnoyarsk 660041, Russia
| | - Vladimir Yu Rudyak
- Faculty of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Oxana O Prishchepa
- Kirensky Institute of Physics, Federal Research Center - Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russia and Institute of Engineering Physics and Radio Electronics, Siberian Federal University, Krasnoyarsk 660041, Russia
| | - Anna P Gardymova
- Institute of Engineering Physics and Radio Electronics, Siberian Federal University, Krasnoyarsk 660041, Russia
| | | | | | - Victor Ya Zyryanov
- Kirensky Institute of Physics, Federal Research Center - Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russia
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Anionic-cationic surfactant mixture providing the electrically controlled homeotropic surface anchoring of liquid crystals. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.02.132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Garbovskiy Y, Glushchenko A. Introduction to the Special Issue of the Journal of Molecular Liquids Dedicated to the Memory of Professor Yuriy Reznikov. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.08.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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