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Huang J, Hu W, Yu M, Ren Y, Zhang L, Yang H. Effects of terpene alcohol dopant on the morphology and electro‐optical properties of polymer‐dispersed liquid‐crystal composite films. POLYM ADVAN TECHNOL 2021. [DOI: 10.1002/pat.5424] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Junyi Huang
- Department of Materials Science and Engineering, College of Engineering Peking University Beijing China
| | - Wei Hu
- Department of Materials Science and Engineering, College of Engineering Peking University Beijing China
| | - Meina Yu
- Institute for Advanced Materials and Technology University of Science and Technology Beijing Beijing China
| | - Yunxiao Ren
- Department of Materials Physics and Chemistry, School of Materials Science and Engineering University of Science and Technology Beijing Beijing China
| | - Lanying Zhang
- Department of Materials Science and Engineering, College of Engineering Peking University Beijing China
| | - Huai Yang
- Department of Materials Science and Engineering, College of Engineering Peking University Beijing China
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2
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Jirón V, Castellón E. Increased Nematic-Isotropic Transition Temperature on Doping a Liquid Crystal with Molecularly Rigid Carboxylic Acids. J Phys Chem B 2020; 124:890-899. [PMID: 31945293 DOI: 10.1021/acs.jpcb.9b09567] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A thermotropic nematic liquid crystal (LC) becomes an isotropic liquid at the nematic-isotropic transition temperature (TNI), which depends on the molecular order of the mesophase. By means of a polarized optical microscope and a differential scanning calorimeter, it was found that doping the nematic liquid crystal 4-n-pentyl-4'-cyanobiphenyl (5CB) with molecularly rigid carboxylic acids (benzoic, 1-naphthoic, 2-naphthoic, and biphenyl-4-carboxylic acids) increases TNI without modification of the nematic-isotropic transition enthalpy. This increment in TNI is due to the increased order caused by the formation of molecularly rigid and elongated dimers of carboxylic acids in the nematic LC, as confirmed with infrared spectra. Furthermore, TNI increased with the length of the molecularly rigid dimers at the same concentration level. Conversely, doping the LC with molecularly flexible acids caused lowering of TNI. A quantitative correlation was established between the TNI increase of the rigid carboxylic acids and the length of the dimers of these acids; a predictive model for these ΔTNI values as a function of acid molar fraction was developed. It was also demonstrated that the doping of 5CB with rigid carboxylic acids increases the rotational viscosity of the liquid crystal.
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Affiliation(s)
- Vanessa Jirón
- Escuela de Quı́mica , Universidad de Costa Rica , San José 11501-2060 , Costa Rica.,Centro de Investigación en Ciencia e Ingenierı́a de Materiales (CICIMA) , Universidad de Costa Rica , San José 11501-2060 , Costa Rica
| | - Erick Castellón
- Escuela de Quı́mica , Universidad de Costa Rica , San José 11501-2060 , Costa Rica.,Centro de Investigación en Ciencia e Ingenierı́a de Materiales (CICIMA) , Universidad de Costa Rica , San José 11501-2060 , Costa Rica
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3
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Shen W, Wang L, Chen G, Li C, Zhang L, Yang Z, Yang H. A facile route towards controllable electric-optical performance of polymer-dispersed liquid crystal via the implantation of liquid crystalline epoxy network in conventional resin. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.01.052] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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4
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Kakiuchida H, Ogiwara A, Matsuyama A. Multiple Bragg Diffractions with Different Wavelengths and Polarizations Composed of Liquid Crystal/Polymer Periodic Phases. ACS OMEGA 2017; 2:6081-6090. [PMID: 31457857 PMCID: PMC6644821 DOI: 10.1021/acsomega.7b01149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 09/07/2017] [Indexed: 06/01/2023]
Abstract
We first fabricated holographic polymer-dispersed liquid crystals (HPDLCs) that produce multiple Bragg diffractions with different polarization states for every angle of incidence, through a photopolymerization-induced phase separation by one-time interferential exposure. The polarizations of the Bragg diffractions were well-controlled at individual wavelengths in the fabrication process by the compositional ratio of LCs to monomers. The raw mixtures of extremely low-functionality monomers having very different viscosities were used to reduce the domain size in phase separation and subsequently to form elaborate periodic structures of the LC and polymer phases. A cross-linker (1-vinyl-2-pyrrolidione) and a prepolymer with urethane groups were employed to strengthen the polymer network. Note that the diffractions of our HPDLCs are regarded as not purely but mostly Bragg type, according to the evaluation with the established criteria. The devices, which are monolithic but versatile in diffractive behaviors, have advantages of simple manufacturing and handling.
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Affiliation(s)
- Hiroshi Kakiuchida
- Structural
Materials Research Institute, National Institute
of Advanced Industrial Science and Technology, 2266-98 Anagahora, Shimoshidami,
Moriyama-ku, Nagoya, Aichi 463-8560, Japan
| | - Akifumi Ogiwara
- Department
of Electronics Engineering, Kobe City College
of Technology, 8-3 Gakuen-higashi, Nishiku, Kobe 651-2194, Japan
| | - Akihiko Matsuyama
- Faculty
of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan
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5
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Binet C, Allart A, Judeinstein P, Roussel F. Anisotropic charge transport in ion-conductive photoresponsive polyethylene oxide-based mesomorphic materials. Phys Rev E 2017; 95:012708. [PMID: 28208449 DOI: 10.1103/physreve.95.012708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Indexed: 11/07/2022]
Abstract
The mechanism of charge motion in conductive and photosensitive mesogenic block copolymers containing polyethylene oxide (PEO) segments is investigated over a wide frequency and temperature range with the broadband dielectric spectroscopy technique. It is found that the ultraviolet (UV) irradiation, the UV intensity, and the anchoring conditions of mesogenic unit in the cells produce changes in conductivity properties and in the molecular arrangement. The anisotropic nature of the conductivity is established.
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Affiliation(s)
- Corinne Binet
- Université de Lille-Sciences et Techniques, Unité Matériaux et Transformations (UMET), CNRS, UMR 8207, UFR de Physique, P5, 59655 Villeneuve d'Ascq Cedex, France
| | - Alexandre Allart
- Université de Lille-Sciences et Techniques, Unité Matériaux et Transformations (UMET), CNRS, UMR 8207, UFR de Physique, P5, 59655 Villeneuve d'Ascq Cedex, France
| | - Patrick Judeinstein
- ICMMO, UMR 8182 CNRS-U. P-Sud, Université Paris-Saclay, Université Paris-Sud, 91405 Orsay Cedex, France.,Laboratoire Léon Brillouin, UMR 12 CNRS-CEA, Université Paris-Saclay, CEA Saclay, 91191 Gif sur Yvette Cedex, France
| | - Frédérick Roussel
- Université de Lille-Sciences et Techniques, Unité Matériaux et Transformations (UMET), CNRS, UMR 8207, UFR de Physique, P5, 59655 Villeneuve d'Ascq Cedex, France
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6
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Ishige R, Shinohara T, White KL, Meskini A, Raihane M, Takahara A, Ameduri B. Unique Difference in Transition Temperature of Two Similar Fluorinated Side Chain Polymers Forming Hexatic Smectic Phase: Poly{2-(perfluorooctyl)ethyl acrylate} and Poly{2-(perfluorooctyl)ethyl vinyl ether}. Macromolecules 2014. [DOI: 10.1021/ma500503z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
| | | | | | - Ahmed Meskini
- Organometallic and Macromolecular Chemistry-Composite
Materials Laboratory − Cadi Ayyad University-Faculté des Sciences et Techniques, Avenue Abdelkrim Khattabi, BP 549, 40000 Marrakech, Morocco
| | - Mustapha Raihane
- Organometallic and Macromolecular Chemistry-Composite
Materials Laboratory − Cadi Ayyad University-Faculté des Sciences et Techniques, Avenue Abdelkrim Khattabi, BP 549, 40000 Marrakech, Morocco
| | - Atsushi Takahara
- Exploratory Research for Advanced Technology
(ERATO), Takahara Soft Interfaces Project, Japan Science and Technology Agency (JST), 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Bruno Ameduri
- Engineering
and Macromolecular Architectures, Institut Charles Gerhardt, UMR (CNRS)
5253, Ecole Nationale Supérieure de Chimie de Montpellier, 8 Rue Ecole Normale, 34296 Montpellier Cedex 5, France
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7
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Boussoualem M, Ismaili M, Roussel F. Influence of surface anchoring conditions on the dielectric and electro-optical properties of nematic droplets dispersed in a polymer network. SOFT MATTER 2014; 10:367-373. [PMID: 24651946 DOI: 10.1039/c3sm52573b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Dielectric and electro-optical properties of liquid crystal (LC) dispersions exhibiting two different surface anchoring conditions at the polymer-LC interface are investigated. The confining surface was tuned by changing the side chains of the polymeric matrix in order to get either planar or homeotropic anchoring conditions and, in turn, bipolar or radial LC droplets, respectively. In the low frequency region of the dielectric spectra, LC dispersions exhibit a broad absorption domain, which has been assigned to a depolarization field effect (Maxwell-Wagner-Sillars (MWS) mechanism). The strength and relaxation frequency of the MWS process are closely related to the geometry of the confined LC phase. In the case of radial droplets, the electrical conductivity dominates whereas for bipolar droplets capacitive effects are predominant. From electro-optical (EO) measurements and numerical simulations of the electric field inside droplets, it is shown that bipolar droplets exhibit enhanced EO performances compared to their radial counterparts. Based on simple topological and electrodynamic approaches, this phenomenon is related to the spatial distribution of charges inside droplets.
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8
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Sung SJ, Jung EA, Kim DH, Son DH, Kang JK, Cho KY. Pixel-isolation liquid crystals formed by polarization-selective UV-curing of a prepolymer containing cinnamate oligomer. OPTICS EXPRESS 2010; 18:11737-11745. [PMID: 20589034 DOI: 10.1364/oe.18.011737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A pixel isolated liquid crystal display was fabricated by polarization-selective anisotropic photoreaction of a prepolymer containing a cinnamate oligomer. The cinnamate oligomer was mainly distributed on the surface region of a UV-cured polymer wall. Anisotropic photo-dimerization of cinnamate moiety was achieved by polarized UV exposure. It was found that the polymer walls containing cinnamate dimers formed by polarized UV exposure showed ordered orientation of LC molecules at the boundary of the polymer walls resulting in electro-optic performance improvement.
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Affiliation(s)
- Shi-Joon Sung
- Public & Original Technology Research Center, Daegu Gyeongbuk Institute of Science & Technology (DGIST), 711 Hosan-dong, Dalseo-gu, Daegu, 704-230, Republic of Korea.
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9
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Castellón E, Zayat M, Levy D. Molecular configuration transitions of a nematic liquid crystal encapsulated in organically modified silicas. Phys Chem Chem Phys 2009; 11:6234-41. [DOI: 10.1039/b903926k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Boussoualem M, Ismaili M, Lamonier JF, Buisine JM, Roussel F. Polarization field effects at liquid-crystal-droplet-polymer interfaces. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:041702. [PMID: 16711822 DOI: 10.1103/physreve.73.041702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Indexed: 05/09/2023]
Abstract
The influence of confinement (droplet size) and liquid crystal orientational order (smectic-A and nematic) on the interfacial polarization field effects [Maxwell-Wagner-Sillars (MWS) effect] existing in liquid-crystal-droplets-polymer systems is investigated by broadband dielectric spectroscopy and a forward transmittance measurement technique. A relaxation process observed in the low frequency domain of the dielectric spectrum has been associated with a MWS effect for both micron-size and submicron-size droplets. Using electro-optical measurements and numerical simulations of the field inside droplets, it is shown that a depolarization field takes place in the same frequency range as that determined by dielectric spectroscopy. Differential scanning calorimetry measurements allowed to estimate the phase-separated liquid crystal [4,4'-octylcyanobiphenyl (8CB)] fraction, which was found in the range of 55% for both micron-size and submicron-size droplets. X-ray diffraction experiments showed that smectic 8CB confined to micron-size cavities adopt bulklike properties, i.e., a partial bilayer structure, whereas in submicron-size droplets the layer spacing of the smectic phase is increased due to the strong bending deformations induced by the high curvature of the cavity walls.
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Affiliation(s)
- Mourad Boussoualem
- Laboratoire de Thermophysique de la Matière Condensée, UMR CNRS 8024, MREI, Université du Littoral-Côte d'Opale, 59140 Dunkerque, France
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11
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Boussoualem M, Roussel F, Ismaili M. Thermophysical, dielectric, and electro-optic properties of nematic liquid crystal droplets confined to a thermoplastic polymer matrix. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:031702. [PMID: 15089305 DOI: 10.1103/physreve.69.031702] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2003] [Indexed: 05/24/2023]
Abstract
The thermophysical, dielectric and electro-optic properties of polymer-dispersed liquid crystal (PDLC) films made of monodisperse polystyrene (PS) and 4-n-pentyl-4(')-cyanobiphenyl (5CB) are investigated by polarized optical microscopy, differential scanning calorimetry, ac impedance analysis, and forward transmittance measurement technique. The PS-5CB system exhibits an upper critical solution temperature (UCST) shape phase diagram with a wide isotropic+isotropic (I+I) miscibility gap between the isotropic and nematic+isotropic (N+I) regions. An absorption domain in the dielectric spectrum of PDLC films was clearly observed at low frequency, and unambiguously assigned to the confined liquid crystalline phase in both nematic and isotropic states. The correlation between the dielectric and electro-optical results for PS-5CB (30:70) samples has shown that in the vicinity of the low frequency absorption domain ( approximately 200 Hz at T=25 degrees C), a drastic decrease in the optical transmittance of the film occurs. This phenomenon can be related to an interfacial polarization process resulting from a charge accumulation at the droplet-polymer interface (Maxwell-Wagner-Sillars effect).
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Affiliation(s)
- Mourad Boussoualem
- Laboratoire de Thermophysique de la Matière Condensée, Equipe de l'UMR CNRS 8024, Université du Littoral-Côte d'Opale, MREI, 59140 Dunkerque, France
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12
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Zhou X, Chen H, Iwamoto M. Orientational order in binary mixtures of hard Gaussian overlap molecules. J Chem Phys 2004; 120:1832-6. [PMID: 15268314 DOI: 10.1063/1.1634954] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Based on a standard constant-pressure Monte Carlo molecular simulation, we have studied liquid crystal phases of binary mixtures of nonspherical molecules. The components of the mixtures are two types of hard Gaussian overlap (HGO) molecules. The first type of molecule has a small molecularelongation parameter (short HGO molecules) and cannot form stable liquid crystal phase in the bulk by themselves. The second type of molecule has a large elongation parameter (long HGO molecules) and can form a liquid crystal phase easily. In the mixtures, the short HGO molecules can form an orientationally ordered phase because the long HGO molecules form confining surfaces to induce the alignment of the short molecules. We also study the isotropic-nematic phase transition in different mixtures composed of short and long HGO molecules with different elongations and concentrations. The obtained result implies that small anisotropic molecules can show liquid crystal behavior.
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Affiliation(s)
- Xin Zhou
- Department of Physical Electronics, Tokyo Institute of Technology, O-okayama 2-12-1, Meguro-ku, Tokyo 152-8552, Japan
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13
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Roussel F, Chan-Yu-King R, Buisine JM. Conducting polymers as driving electrodes for Polymer-Dispersed Liquid-Crystals display devices: on the electro-optical efficiency. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2003; 11:293-300. [PMID: 15011049 DOI: 10.1140/epje/i2002-10158-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Intrinsically conducting polymer (ICP) thin films are used as driving electrodes for Polymer-Dispersed Liquid-Crystals (PDLC) display devices. In order to investigate the electro-optical efficiency of these organic electrodes, three different kinds of conducting polymers, i.e. polyaniline doped with 10-camphorsulfonic acid (PANI(HCSA)), polypyrrole doped with dodecylbenzenesulfonic acid (PPY(DBSA)), and polyethylenedioxythiophene doped with polystyrenesulfonate (PEDOT(PSS)), were prepared or purchased, and coated either on glass or plastic substrates. Optical absorption studies in the UV-Vis range of the conducting polymer-coated substrates were first performed showing the presence of conducting species for the three types of polymers. The electrical characteristics of the resulting films were measured with the four-probes technique. PANI(HCSA) exhibits a higher conductivity sigma approximately 122 S x cm(-1) (RS=1.2x10(3) Omega x (-1)) compared to PPY(DBSA) sigma approximately 2.6 S x cm(-1) (RS=150.7x10(3) Omega x (-1)), and PEDOT(PSS) sigma approximately 1.6 S x cm(-1) (RS=637.3x10(3) Omega x (-1)). It is also shown that for a given conducting polymer, its electrical conductivity decreases when a plastic substrate is used. These observations have been related to significant morphological changes observed by scanning electron microscopy (SEM). A mixture of Norland Optical Adhesive 65 and nematic liquid-crystal E7 in the weight ratio (35:65) was used as precursor of the PDLC material. Better electro-optical responses (transmission properties, drive voltages and switching times) of PDLC films were obtained for devices prepared with (PPY(DBSA))-based electrodes. The electro-optical performances of the PDLC display devices also depend on the nature of the ICP substrate used.
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Affiliation(s)
- F Roussel
- Laboratoire de Thermophysique de la Matière Condensée, UMR CNRS 8024 - Université du Littoral-Côte d'Opale, MREID, 59140, Dunkerque, France.
| | - R Chan-Yu-King
- Laboratoire de Thermophysique de la Matière Condensée, University of Science and Arts of Oklahoma, OK 73018, Chickasha, USA
| | - J-M Buisine
- Laboratoire de Thermophysique de la Matière Condensée, UMR CNRS 8024 - Université du Littoral-Côte d'Opale, MREID, 59140, Dunkerque, France
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