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Cousins JRL, Duffy BR, Wilson SK, Mottram NJ. Young and Young-Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states. Proc Math Phys Eng Sci 2022; 478:20210849. [PMID: 35370444 PMCID: PMC8966048 DOI: 10.1098/rspa.2021.0849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 02/25/2022] [Indexed: 11/22/2022] Open
Abstract
Motivated by the need for greater understanding of systems that involve interfaces between a nematic liquid crystal, a solid substrate and a passive gas that include nematic-substrate-gas three-phase contact lines, we analyse a two-dimensional static ridge of nematic resting on a solid substrate in an atmosphere of passive gas. Specifically, we obtain the first complete theoretical description for this system, including nematic Young and Young-Laplace equations, and then, making the assumption that anchoring breaking occurs in regions adjacent to the contact lines, we use the nematic Young equations to determine the continuous and discontinuous transitions that occur between the equilibrium states of complete wetting, partial wetting and complete dewetting. In particular, in addition to continuous transitions analogous to those that occur in the classical case of an isotropic liquid, we find a variety of discontinuous transitions, as well as contact-angle hysteresis, and regions of parameter space in which there exist multiple partial wetting states that do not occur in the classical case.
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Affiliation(s)
- Joseph R. L. Cousins
- Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, UK
- School of Mathematics and Statistics, University of Glasgow, University Place, Glasgow G12 8QQ, UK
| | - Brian R. Duffy
- Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, UK
| | - Stephen K. Wilson
- Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, UK
| | - Nigel J. Mottram
- Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, UK
- School of Mathematics and Statistics, University of Glasgow, University Place, Glasgow G12 8QQ, UK
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Rijeesh K, Higuchi H, Okumura Y, Yamamoto J, Kikuchi H. Liquid crystal anchoring transitions and weak anchoring interface formation at surfaces created by uniquely designed acrylate copolymers. POLYMER 2017. [DOI: 10.1016/j.polymer.2016.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Stetsyshyn Y, Raczkowska J, Budkowski A, Awsiuk K, Kostruba A, Nastyshyn S, Harhay K, Lychkovskyy E, Ohar H, Nastishin Y. Cholesterol-Based Grafted Polymer Brushes as Alignment Coating with Temperature-Tuned Anchoring for Nematic Liquid Crystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11029-11038. [PMID: 27689751 DOI: 10.1021/acs.langmuir.6b02946] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Novel alignment coating with temperature-tuned anchoring for nematic liquid crystals (NLCs) was successfully fabricated in three step process, involving polymerization of poly(cholesteryl methacrylate) (PChMa) from oligoproxide grafted to the glass surface premodified with 3-aminopropyltriethoxysilane. Molecular composition, thickness, wettability of the PChMa coating and its alignment action for a NLC were examined with time of flight-secondary ion mass spectrometry, ellipsometry, contact angle measurements, polarization optical microscopy and commercially produced PolScope technique allowing for mapping of the optic axis and optical retardance within the microscope field view. We find that the PChMa coating provides a specific monotonous increase (decrease) in the tilt angle of the NLC director with respect to the substrates normal upon heating (cooling) referred to as anchoring tuning.
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Affiliation(s)
- Yurij Stetsyshyn
- Lviv Polytechnic National University , S. Bandery 12, 79013 Lviv, Ukraine
| | - Joanna Raczkowska
- Smoluchowski Institute of Physics, JagiellonianUniversity , Łojasiewicza 11, 30-348 Kraków, Poland
| | - Andrzej Budkowski
- Smoluchowski Institute of Physics, JagiellonianUniversity , Łojasiewicza 11, 30-348 Kraków, Poland
| | - Kamil Awsiuk
- Smoluchowski Institute of Physics, JagiellonianUniversity , Łojasiewicza 11, 30-348 Kraków, Poland
| | - Andriy Kostruba
- Lviv Academy of Commerce , Samtshuk 9, Lviv 79005 Ukraine
- Vlokh Institute of Physical Optics , 23 Dragomanov st., Lviv 79011, Ukraine
| | | | - Khrystyna Harhay
- Lviv Polytechnic National University , S. Bandery 12, 79013 Lviv, Ukraine
| | - Edward Lychkovskyy
- Lviv Danylo Halytsky National Medical University , Pekarska 69, 79010 Lviv, Ukraine
| | - Halyna Ohar
- Lviv Polytechnic National University , S. Bandery 12, 79013 Lviv, Ukraine
| | - Yuriy Nastishin
- Vlokh Institute of Physical Optics , 23 Dragomanov st., Lviv 79011, Ukraine
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Bhargavi R, Nair GG, Prasad SK. Anchoring transition induced by gelation in a liquid crystal system. Chemphyschem 2013; 14:331-7. [PMID: 23255349 DOI: 10.1002/cphc.201200920] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Indexed: 11/05/2022]
Abstract
We report a novel type of anchoring transition (ANT) in a liquid crystal driven by the physical gelation of the system. The ANT manifests as anomaly in the thermal behaviour of the dielectric permittivity. Data from X-ray studies suggest that ANT is caused by the ability of the gel fibres to compete with the substrate-driven orientation conditions. It is further found that the molecular reorientation is possible only in cases where the gel is weak, the difference between weak and strong gels being established by rheological measurements.
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Affiliation(s)
- R Bhargavi
- Centre for Soft Matter Research, Bangalore, India
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Wang JJ, Li XS. Improved oxygen permeability and mechanical strength of silicone hydrogels with interpenetrating network structure. CHINESE JOURNAL OF POLYMER SCIENCE 2010. [DOI: 10.1007/s10118-010-9142-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Yoon HG, Kang SW, Dong RY, Marini A, Suresh KA, Srinivasarao M, Kumar S. Nematic biaxiality in a bent-core material. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:051706. [PMID: 20866246 DOI: 10.1103/physreve.81.051706] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 02/21/2010] [Indexed: 05/29/2023]
Abstract
The results of a recent investigation of the nematic biaxiality in a bent-core mesogen (A131) are in apparent disagreement with earlier claims. Samples of mesogen A131 used in the two studies were investigated with polarized optical microscopy, conoscopy, carbon-13 NMR, and crossover frequency measurements. The results demonstrate that textural changes associated with the growth of biaxial nematic order appear at ∼149 °C. The Maltese cross observed in the conoscopic figure gradually splits into two isogyres at lower temperatures indicating phase biaxiality. Presence of the uniaxial to biaxial nematic phase transition is further confirmed by temperature trends of local order parameters based on 13C chemical shifts in NMR experiments. Frequency switching measurements also clearly reveal a transition at 149 °C. Differences between the two reports appear to be related to the presence of solvent, impurities, and/or adsorbed gases in samples of A131 used in the study of Van Le [Phys. Rev. E 79, 030701 (2009)].
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Affiliation(s)
- Hyung Guen Yoon
- Department of Physics, Kent State University, Kent, Ohio 44242, USA
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Wang J, Sun F, Li X. Preparation and antidehydration of interpenetrating polymer network hydrogels based on 2-hydroxyethyl methacrylate andN-vinyl-2-pyrrolidone. J Appl Polym Sci 2010. [DOI: 10.1002/app.32150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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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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Application and New Developments in Polymer-Dispersed Liquid Crystal Simulation Studies. MACROMOL THEOR SIMUL 2007. [DOI: 10.1002/mats.200700008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Aoki Y, Watabe T, Hirose T, Ishikawa K. Noble Orientation Change with Temperature in Nematic Liquid Crystalline Mixtures. CHEM LETT 2007. [DOI: 10.1246/cl.2007.380] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Zhou J, Park JO, De Luca G, Rey AD, Srinivasarao M. Microscopic observations and simulations of Bloch walls in nematic thin films. PHYSICAL REVIEW LETTERS 2006; 97:157801. [PMID: 17155362 DOI: 10.1103/physrevlett.97.157801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Indexed: 05/12/2023]
Abstract
We study Bloch wall defects formed by quenching nematic thin films from planar anchoring to homeotropic anchoring through a temperature-driven anchoring transition. The director profiles of the walls are directly visualized using fluorescence confocal polarizing microscopy, and shown to agree well with the simulation based on the Frank elasticity theory. A pure twist wall exists if the ratio of sample thickness to surface extrapolation length p is smaller than or close to 1; while a diffuse Bloch wall is obtained if p is much greater than 1.
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Affiliation(s)
- Jian Zhou
- School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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Zhou J, Collard DM, Srinivasarao M. Switchable gratings by spatially periodic alignment of liquid crystals via patterned photopolymerization. OPTICS LETTERS 2006; 31:652-4. [PMID: 16570428 DOI: 10.1364/ol.31.000652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Spatially periodic patterning of the anchoring condition of a nematic liquid crystal (NLC) within a polymer matrix via a patterned photopolymerization affords a novel and facile method to prepare electrically switchable diffraction gratings. UV irradiation through a photomask of two comonomers, with opposite tendencies to align the NLC and also with different reactivity ratios, leads to definition of areas with either homeotropic or planar alignment of the NLC. Photopolymerization-induced diffusion of the monomers accounts for the spatial distribution of the concentration of these monomers. The resulting diffraction gratings are switchable under low electric fields and possess structural stability offered by the polymer matrix.
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Affiliation(s)
- Jian Zhou
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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