1
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Yadav N, Panarin YP, Jiang W, Mehl GH, Vij JK. Spontaneous mirror symmetry breaking and chiral segregation in the achiral ferronematic compound DIO. Phys Chem Chem Phys 2023; 25:9083-9091. [PMID: 36919840 DOI: 10.1039/d3cp00357d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
An achiral compound, DIO, known to exhibit three nematic phases namely N, NX and NF, is studied by polarizing microscopy and electro-optics for different surface conditions in confinement. The high temperature N phase assigned initially as a conventional nematic phase, shows two additional unusual features: the optical activity and the linear electro-optic response related to the polar nature of this phase. An appearance of chiral domains is explained by the spontaneous symmetry breaking arising from the saddle-splay elasticity and followed by the formation of helical domains of the opposite chirality. This is the first example of helical segregation observed in calamitic non-chiral molecules in the nematic phase. As reported previously, the ferronematic NF shows strong polar azimuthal surface interaction energy which stabilizes a homogeneous structure in planar aligned LC cells rubbed parallel and exhibits a twisted structure in cells with antiparallel buffing. The transmission spectra are simulated using Berreman's 4 × 4 matrix method. The observed agreement between the experimental and the simulated spectra quantitatively confirms the presence of twisted structures in antiparallel rubbed cells.
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Affiliation(s)
- Neelam Yadav
- Department of Electronic and Electrical Engineering, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland.
| | - Yuri P Panarin
- Department of Electrical and Electronic Engineering, TU Dublin, Dublin 7, Ireland
| | - Wanhe Jiang
- Department of Chemistry, University of Hull, Hull, HU6 7RX, UK
| | - Georg H Mehl
- Department of Chemistry, University of Hull, Hull, HU6 7RX, UK
| | - Jagdish K Vij
- Department of Electronic and Electrical Engineering, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland.
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2
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Ali M. Diffraction gratings formed spontaneously by a two-dimensional undulation of the pseudo-layer structure of a twist-bend nematic phase. LIQUID CRYSTALS TODAY 2022. [DOI: 10.1080/1358314x.2022.2168968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- M. Ali
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Chemistry, University of Warsaw, Warsaw, Poland
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3
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Arakawa Y, Komatsu K, Shiba T, Tsuji H. Phase behaviors of classic liquid crystal dimers and trimers: Alternate induction of smectic and twist-bend nematic phases depending on spacer parity for liquid crystal trimers. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115319] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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4
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Ali M, Gorecka E, Pociecha D, Vaupotič N. Structure and grating efficiency of thin cells filled by a twist-bend nematic liquid crystal. Phys Rev E 2020; 102:032704. [PMID: 33075896 DOI: 10.1103/physreve.102.032704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/31/2020] [Indexed: 11/07/2022]
Abstract
A twist-bend nematic (N_{TB}) liquid crystalline phase spontaneously forms modulated structures on a microscale level when confined in thin planar cells. Preliminary studies showed that these cells can be used as polarization gratings. Here we present a theoretical description of the formation of a two-dimensionally modulated structure. By considering the N_{TB} phase as a pseudolayer medium, a threshold condition for the onset of a modulated structure is calculated for weak and strong boundary conditions in the case of initially bookshelf or pretilt alignment of pseudolayers. Based on the modeled structure we determine spatial variation of the optic axis and calculate properties of the transmitted diffracted light. Results of the beam propagation method (BPM) and transfer matrix method are compared and it is shown that a more complex BPM gives better agreement with experimental results, meaning that even in thin cells the diffraction of light inside the grating should not be neglected.
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Affiliation(s)
- M Ali
- Faculty of Chemistry, University of Warsaw, Zwirki i Wigury 101, 02-089 Warsaw, Poland.,Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia
| | - E Gorecka
- Faculty of Chemistry, University of Warsaw, Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - D Pociecha
- Faculty of Chemistry, University of Warsaw, Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - N Vaupotič
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia.,Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
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5
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Šmahel M, Poryvai A, Xiang Y, Pociecha D, Troha T, Novotná V, Svoboda J, Kohout M. Photosensitive bent-core nematic liquid crystals with various linking units in the side arms: Structure-properties relationships. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112743] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Alaasar M, Prehm M, Belau S, Sebastián N, Kurachkina M, Eremin A, Chen C, Liu F, Tschierske C. Polar Order, Mirror Symmetry Breaking, and Photoswitching of Chirality and Polarity in Functional Bent‐Core Mesogens. Chemistry 2019; 25:6362-6377. [DOI: 10.1002/chem.201806180] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/21/2019] [Indexed: 01/06/2023]
Affiliation(s)
- Mohamed Alaasar
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
- Department of Chemistry, Faculty of ScienceCairo University Giza Egypt
| | - Marko Prehm
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
| | - Sebastian Belau
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Nerea Sebastián
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Marharyta Kurachkina
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Changlong Chen
- State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong University Xi'an 710049 P. R. China
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong University Xi'an 710049 P. R. China
| | - Carsten Tschierske
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
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7
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Potisk T, Pleiner H, Brand HR. Influence of tetrahedral order on ferromagnetic gel phases. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:35. [PMID: 30900106 DOI: 10.1140/epje/i2019-11798-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/15/2019] [Indexed: 06/09/2023]
Abstract
We investigate the macroscopic dynamics of gels with tetrahedral/octupolar symmetry, which possess in addition a spontaneous permanent magnetization. We derive the corresponding static and dynamic macroscopic equations for a phase, where the magnetization is parallel to one of the improper fourfold tetrahedral symmetry axes. Apart from elastic strains, we take into account relative rotations between the magnetization and the elastic network. The influence of tetrahedral order on these degrees of freedom is investigated and some experiments are proposed that are specific for such a material and allow to indirectly detect tetrahedral order. We also consider the case of a transient network and predict that stationary elastic shear stresses arise when a temperature gradient is applied.
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Affiliation(s)
- Tilen Potisk
- Department of Physics, University of Bayreuth, 95440, Bayreuth, Germany
| | - Harald Pleiner
- Max Planck Institute for Polymer Research, 55021, Mainz, Germany.
| | - Helmut R Brand
- Department of Physics, University of Bayreuth, 95440, Bayreuth, Germany
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8
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Huang Z, Qi P, Liu Y, Chai C, Wang Y, Song A, Hao J. Ionic-surfactants-based thermotropic liquid crystals. Phys Chem Chem Phys 2019; 21:15256-15281. [DOI: 10.1039/c9cp02697e] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ionic surfactants can be combined with various functional groups through electrostatic interaction, resulting in a series of thermotropic liquid crystals (TLCs).
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Affiliation(s)
- Zhaohui Huang
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Ping Qi
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Yihan Liu
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Chunxiao Chai
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Yitong Wang
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Aixin Song
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Jingcheng Hao
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
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9
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Cybotactic nematic phase of achiral unsymmetrical bent-core liquid crystals – Quelling of polar ordering and the influence of terminal substituent moiety. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.02.097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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10
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Panarin YP, Sreenilayam SP, Vij JK, Lehmann A, Tschierske C. Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1288-1296. [PMID: 29765807 PMCID: PMC5942366 DOI: 10.3762/bjnano.9.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 03/28/2018] [Indexed: 05/23/2023]
Abstract
Two homologue achiral bent-core liquid crystals (LCs), BCN66 and BCN84, in their nematic phases are studied by dielectric spectroscopy in the frequency range 10 Hz-10 MHz. In each of these compounds, two relaxation processes are identified and assigned to (i) collective dynamics of molecules in nanometer-sized cybotactic clusters and (ii) individual molecular relaxations, in the ascending order of frequency of the probe field. The temperature and the bias electric field dependence of the dielectric strength and relaxation frequency for these processes are shown to give rise to sharpness in cluster boundaries, increased size and volume fraction in the LC nematic phase. The effect of the bias field on the LC cell is similar to reducing its temperature; both variables increase the cluster size and volume fraction and give rise to sharp cluster boundaries. The findings confirm that dielectric spectroscopy is a powerful and an extremely useful technique to provide a deeper understanding of the mechanism of cybotactic cluster formation in the isotropic liquid and the nematic phase of LCs as a function of temperature and the bias field.
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Affiliation(s)
- Yuri P Panarin
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
- School of Electrical and Electronic Engineering, Dublin Institute of Technology, Dublin 8, Ireland
| | - Sithara P Sreenilayam
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Jagdish K Vij
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Anne Lehmann
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany
| | - Carsten Tschierske
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany
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11
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Salamończyk M, Vaupotič N, Pociecha D, Wang C, Zhu C, Gorecka E. Structure of nanoscale-pitch helical phases: blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering. SOFT MATTER 2017; 13:6694-6699. [PMID: 28871294 DOI: 10.1039/c7sm00967d] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Periodic structures of phases with orientational order of molecules but homogenous electron density distribution: a short pitch cholesteric phase, blue phase and twist-bend nematic phase, were probed by resonant soft X-ray scattering (RSoXS) at the carbon K-edge. The theoretical model shows that in the case of a simple heliconical nematic structure, two resonant signals corresponding to the full and half pitch band should be present, while only the full pitch band is observed experimentally. This suggests that the twist-bend nematic phase has a complex structure with a double-helix built of two interlocked, shifted helices. We confirm that the helical pitch in the twist-bend nematic phase is in a 10 nm range for both the chiral and achiral materials. We also show that the symmetry of the blue phase can be unambiguously determined through a resonant enhancement of the X-ray diffraction signals, by including polarization effects, which are found to be an important indicator in phase structure determination.
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Affiliation(s)
- Mirosław Salamończyk
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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12
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Dietrich CF, Rudquist P, Lorenz K, Giesselmann F. Chiral Structures from Achiral Micellar Lyotropic Liquid Crystals under Capillary Confinement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5852-5862. [PMID: 28509558 DOI: 10.1021/acs.langmuir.7b01074] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recently, the emergence of spontaneous reflection-symmetry-broken configurations in achiral chromonic liquid crystals confined in cylindrical capillaries with homeotropic anchoring at the cylinder walls was reported, namely, the so-called twisted-escaped radial (TER) and twisted planar polar (TPP) configurations. This new example of spontaneous reflection symmetry breaking in liquid crystals was attributed to the twist elastic modulus, which is known to be unusually small in comparison to the splay and bend moduli in the case of chromonic liquid crystals. We now report the experimental observation of reflection symmetry breaking in cylindrical capillaries in the case of a classical, achiral, and nonchromonic lyotropic liquid crystal forming a nematic phase of disklike micelles orienting homeotropically at the capillary walls. We observed the same chiral TER configuration, as well as a nonplanar twisted polar (TP) configuration. The TP configuration is characterized by two half-unit so-called twist disclinations, where the director twist around the line defects drives the formation of a double helix of the disclinations along the axis of the capillary. Additionally, there is a transverse twist between the two disclination lines with the same handedness as the axial twist. Similarities with and differences from the case of chromonic liquid crystals are discussed; in particular, we examine the conditions under which spontaneous reflection symmetry breaking occurs in the nonchromonic system. It seems that the chiral TER configuration can be stabilized by the presence of point defects.
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Affiliation(s)
- Clarissa F Dietrich
- Institute of Physical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Per Rudquist
- Microelectronics and Nanoscience, Chalmers University of Technology , 41296 Göteborg, Sweden
| | - Kristin Lorenz
- Institute of Physical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Frank Giesselmann
- Institute of Physical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
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13
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Bergquist L, Zhang C, Ribeiro de Almeida RR, Pellegrene B, Salamonczyk M, Kim M, Hwang J, Kim K, Lee J, Jákli A, Hegmann T. An Optically Isotropic Antiferroelectric Liquid Crystal (OI-AFLC) Display Mode Operating over a Wide Temperature Range using Ternary Bent-Core Liquid Crystal Mixtures. ChemistryOpen 2017; 6:196-200. [PMID: 28413750 PMCID: PMC5390793 DOI: 10.1002/open.201600138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/15/2016] [Indexed: 11/06/2022] Open
Abstract
We report on the synthesis and characterization of bent-core liquid crystal (LC) compounds and the preparation of mixtures that provide an optically isotropic antiferroelectric (OI-AFLC) liquid crystal display mode over a very wide temperature interval and well below room temperature. From the collection of compounds synthesized during this study, we recognized that several ternary mixtures displayed a modulated SmCaPA phase down to below -40 °C and up to about 100 °C on both heating and cooling, as well as optical tilt angles in the transformed state of approximately 45° (optically isotropic state). The materials were fully characterized and their liquid crystal as well as electro-optical properties analyzed by polarized optical microscopy, differential scanning calorimetry, synchrotron X-ray diffraction, dielectric spectroscopy, and electro-optical tests.
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Affiliation(s)
- Leah Bergquist
- Chemical Physics Interdisciplinary ProgramLiquid Crystal InstituteKent State UniversityKentOH44242-0001USA
| | - Cuiyu Zhang
- Chemical Physics Interdisciplinary ProgramLiquid Crystal InstituteKent State UniversityKentOH44242-0001USA
| | - Roberta R. Ribeiro de Almeida
- Chemical Physics Interdisciplinary ProgramLiquid Crystal InstituteKent State UniversityKentOH44242-0001USA
- Department of PhysicsFederal University of TechnologyApucaranaPR 86812-460Brazil
| | - Brittany Pellegrene
- Department of Chemistry and BiochemistryKent State UniversityKentOH44242-0001USA
| | - Miroslaw Salamonczyk
- Chemical Physics Interdisciplinary ProgramLiquid Crystal InstituteKent State UniversityKentOH44242-0001USA
- Advanced Light SourceLawrence Berkeley National LaboratoryBerkeleyCA94720USA
| | - Matthew Kim
- Chemical Physics Interdisciplinary ProgramLiquid Crystal InstituteKent State UniversityKentOH44242-0001USA
| | - Jung‐Im Hwang
- LG Display Co., Ltd.245, LG-ro, Wollong-myeon, Paju-siGyeonggi-do413-779South Korea
| | - Kyeong‐Jin Kim
- LG Display Co., Ltd.245, LG-ro, Wollong-myeon, Paju-siGyeonggi-do413-779South Korea
| | - Joun‐Ho Lee
- LG Display Co., Ltd.245, LG-ro, Wollong-myeon, Paju-siGyeonggi-do413-779South Korea
| | - Antal Jákli
- Chemical Physics Interdisciplinary ProgramLiquid Crystal InstituteKent State UniversityKentOH44242-0001USA
| | - Torsten Hegmann
- Chemical Physics Interdisciplinary ProgramLiquid Crystal InstituteKent State UniversityKentOH44242-0001USA
- Department of Chemistry and BiochemistryKent State UniversityKentOH44242-0001USA
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14
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Brand HR, Pleiner H. On the influence of a network on optically isotropic fluid phases with tetrahedral/octupolar order. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2017; 40:34. [PMID: 28337650 DOI: 10.1140/epje/i2017-11523-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 03/01/2017] [Indexed: 06/06/2023]
Abstract
We investigate the influence of transient or permanent elasticity on liquid phases with octupolar (tetrahedral) order, a question that has never been addressed before. The focus will be on optically isotropic liquid phases with tetrahedral order including the T d phase and the chiral T phase introduced by Fel. It turns out that the presence of both, a network as well as tetrahedral order can lead to the formation of chiral domains of both hands in an optically isotropic fluid due to a completely novel mechanism, thus providing a possible macroscopic explanation for recent experimental observations. We study in detail how elasticity influences the macroscopic dynamics of both, the T d and the T phase. The simultaneous presence of a transient network as well as of octupolar order is shown to lead to completely new cross-coupling phenomena for optically isotropic systems including transient dissipative elastic strains due to temperature gradients.
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Affiliation(s)
- Helmut R Brand
- Theoretische Physik III, Universität Bayreuth, 95440, Bayreuth, Germany
- Max-Planck-Institute for Polymer Research, POBox 3148, 55021, Mainz, Germany
| | - Harald Pleiner
- Max-Planck-Institute for Polymer Research, POBox 3148, 55021, Mainz, Germany.
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15
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Kaur S, Punjani V, Mohiuddin G, Pal SK. Orthogonal smectic and nematic ordering in three-ring polar bent-core molecules with anti-parallel arrangement. NEW J CHEM 2017. [DOI: 10.1039/c7nj00272f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three-ring based BLCs exhibiting orthogonal smectic and nematic phases with antiparallel arrangement as derived from SCXRD and X-ray scattering results.
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Affiliation(s)
- Supreet Kaur
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
| | - Vidhika Punjani
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
| | - Golam Mohiuddin
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
| | - Santanu Kumar Pal
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
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16
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Brand HR, Pleiner H, Svenšek D. Macroscopic behavior of polar nematic gels and elastomers. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:105. [PMID: 27822626 DOI: 10.1140/epje/i2016-16105-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 10/05/2016] [Indexed: 06/06/2023]
Abstract
We present the derivation of the macroscopic equations for uniaxial polar nematic gels and elastomers. We include the strain field as well as relative rotations as independent dynamic macroscopic degrees of freedom. As a consequence, special emphasis is laid on possible static and dynamic cross-couplings between these macroscopic degrees of freedom associated with the network, and the other macroscopic degrees of freedom including reorientations of the macroscopic polarization. In particular, we find static and dissipative dynamic cross-couplings between strain fields and relative rotations on one hand and the macroscopic polarization on the other that allow for new possibilities to manipulate polar nematics. To give one example each for the effects of a static and a dissipative cross-coupling: we find that a static electric field applied perpendicularly to the polar preferred direction leads to relative rotations while dynamically relative rotations can lead to transverse electric currents. In addition to a permanent network, we also consider the effect of a transient network, which is particularly important for the case of gels, melts and concentrated polymer solutions. A section on the influence of macroscopic chirality is included as well.
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Affiliation(s)
- Helmut R Brand
- Theoretische Physik III, Universität Bayreuth, 95440, Bayreuth, Germany
- Max-Planck-Institute for Polymer Research, POBox 3148, 55021, Mainz, Germany
| | - Harald Pleiner
- Max-Planck-Institute for Polymer Research, POBox 3148, 55021, Mainz, Germany.
| | - Daniel Svenšek
- Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, 1000, Ljubljana, Slovenia
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17
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Kang S, Lee EW, Li T, Liang X, Tokita M, Nakajima K, Watanabe J. Two-Dimensional Skyrmion Lattice Formation in a Nematic Liquid Crystal Consisting of Highly Bent Banana Molecules. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201606388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sungmin Kang
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Eun-Woo Lee
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Tianqi Li
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Xiaobin Liang
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Masatoshi Tokita
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Ken Nakajima
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Junji Watanabe
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
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18
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Wang J, Liu XQ, Ren XK, Zhang B, Yang S, Cao Y, Liu F, Lotz B, Chen EQ. Helical Polyacetylene-Based Switchable Chiral Columnar Phases: Frustrated Chain Packing and Two-Way Shape Actuator. Chem Asian J 2016; 11:2387-91. [DOI: 10.1002/asia.201600879] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Jun Wang
- Beijing National Laboratory for Molecular Sciences; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; College of Chemistry; Peking University; Beijing 100871 P. R. China
| | - Xiao-Qing Liu
- Beijing National Laboratory for Molecular Sciences; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; College of Chemistry; Peking University; Beijing 100871 P. R. China
| | - Xiang-Kui Ren
- School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 P. R. China
| | - Ben Zhang
- Beijing National Laboratory for Molecular Sciences; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; College of Chemistry; Peking University; Beijing 100871 P. R. China
| | - Shuang Yang
- Beijing National Laboratory for Molecular Sciences; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; College of Chemistry; Peking University; Beijing 100871 P. R. China
| | - Yu Cao
- State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 P. R. China
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 P. R. China
| | - Bernard Lotz
- Institut Charles Sadron; CNRS-Université de Strasbourg; Strasbourg 67034 France
| | - Er-Qiang Chen
- Beijing National Laboratory for Molecular Sciences; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; College of Chemistry; Peking University; Beijing 100871 P. R. China
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19
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Kang S, Lee EW, Li T, Liang X, Tokita M, Nakajima K, Watanabe J. Two-Dimensional Skyrmion Lattice Formation in a Nematic Liquid Crystal Consisting of Highly Bent Banana Molecules. Angew Chem Int Ed Engl 2016; 55:11552-6. [DOI: 10.1002/anie.201606388] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Sungmin Kang
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Eun-Woo Lee
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Tianqi Li
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Xiaobin Liang
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Masatoshi Tokita
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Ken Nakajima
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
| | - Junji Watanabe
- Department of Chemical Science and Engineering; School of Materials and Chemical Technology; Tokyo Institute of Technology; 2-12-1 O-okayama Tokyo 152-8552 Japan
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20
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Vaupotič N, Curk S, Osipov MA, Čepič M, Takezoe H, Gorecka E. Short-range smectic fluctuations and the flexoelectric model of modulated nematic liquid crystals. Phys Rev E 2016; 93:022704. [PMID: 26986385 DOI: 10.1103/physreve.93.022704] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Indexed: 06/05/2023]
Abstract
We show that the flexoelectric model of chiral and achiral modulated nematics predicts the compression modulus that is by orders of magnitude lower than the measured values. The discrepancy is much larger in the chiral modulated nematic phase, in which the measured value of the compression modulus is of the same order of magnitude as in achiral modulated nematics, even though the heliconical pitch is by an order of magnitude larger. The relaxation of a one-constant approximation in the biaxial elastic model used for chiral modulated nematics does not solve the problem. Therefore, we propose a structural model of the modulated nematic phase, which is consistent with the current experimental evidence and can also explain large compression modulus: the structure consists of short-range smectic clusters with a fourfold symmetry and periodicity of two molecular distances. In chiral systems, chiral interactions lead to a helicoidal structure of such clusters.
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Affiliation(s)
- Nataša Vaupotič
- Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia
- Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Samo Curk
- Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia
| | - Mikhail A Osipov
- Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, G1 Glasgow, United Kingdom
| | - Mojca Čepič
- Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Faculty of Education, University of Ljubljana, Kardeljeva ploščad 16, 1000 Ljubljana, Slovenia
| | - Hideo Takezoe
- Toyota Physical and Chemical Research Institute, 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
- Department of Chemistry, University of Warsaw, Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Ewa Gorecka
- Department of Chemistry, University of Warsaw, Zwirki i Wigury 101, 02-089 Warsaw, Poland
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21
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Meyer C, Dozov I. Local distortion energy and coarse-grained elasticity of the twist-bend nematic phase. SOFT MATTER 2016; 12:574-580. [PMID: 26503741 DOI: 10.1039/c5sm02018b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The recently discovered twist-bend nematic phase of achiral bent-shaped molecules, NTB, has a doubly degenerate ground-state with a periodically modulated heliconical structure and unusual distortion elasticity, the theoretical description of which is still debated. We show that the NTB phase has the same macroscopic symmetry as another periodic mesophase, the chiral smectic-A, SmA*. Based on this NTB/SmA* analogy, we develop a coarse-grained elastic model for the NTB phase. Adopting one of the existing microscopic NTB elastic models, we calculate the coarse-grained elastic constants, coherence and penetration lengths in terms of a few Frank-like nematic elastic coefficients that can be measured in macroscopic experiments. The same coarse-grained approach, applied to different local elastic models, may provide an efficient experimental test of their validity. We show that the anisotropy of the NTB coarse-grained elasticity is opposite to that of the SmA*, leading probably to different configurations of some of the defects of the "layered" NTB structure. Moreover, we argue that the intrinsic chiral frustration of the NTB phase may be resolved by penetration of the twist field into the bulk through a network of screw dislocations of the NTB pseudo-layers, resulting in a twist-bend analogue of the twist grain boundary phase TGBA.
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Affiliation(s)
- C Meyer
- Physique des Systèmes Complexes, Université de Picardie Jules Verne, 80039 Amiens, France.
| | - I Dozov
- Physique des Systèmes Complexes, Université de Picardie Jules Verne, 80039 Amiens, France. and Laboratoire de Physique des Solides, UMR 8502 CNRS-Université Paris-Sud, Bât. 510, 91405 Orsay Cedex, France
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22
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Alaasar M, Prehm M, Cao Y, Liu F, Tschierske C. Spontaneous Mirror-Symmetry Breaking in Isotropic Liquid Phases of Photoisomerizable Achiral Molecules. Angew Chem Int Ed Engl 2016; 55:312-6. [PMID: 26490058 DOI: 10.1002/anie.201508097] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Indexed: 11/07/2022]
Abstract
Spontaneous mirror-symmetry breaking is of fundamental importance in science as it contributes to the development of chiral superstructures and new materials and has a major impact on the discussion around the emergence of uniform chirality in biological systems. Herein we report chirality synchronization, leading to spontaneous chiral conglomerate formation in isotropic liquids of achiral and photoisomerizable azobenzene-based rod-like molecules. The position of fluorine substituents at the aromatic core is found to have a significant effect on the stability and the temperature range of these chiral liquids. Moreover, these liquid conglomerates occur in a new phase sequence adjacent to a 3D tetragonal mesophase.
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Affiliation(s)
- Mohamed Alaasar
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle/Saale (Germany). .,Department of Chemistry, Faculty of Science, Cairo University, P.O. 12613 Giza (Egypt).
| | - Marko Prehm
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle/Saale (Germany)
| | - Yu Cao
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049 (P. R. China)
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049 (P. R. China).
| | - Carsten Tschierske
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle/Saale (Germany).
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23
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López DO, Robles-Hernández B, Salud J, de la Fuente MR, Sebastián N, Diez-Berart S, Jaen X, Dunmur DA, Luckhurst GR. Miscibility studies of two twist-bend nematic liquid crystal dimers with different average molecular curvatures. A comparison between experimental data and predictions of a Landau mean-field theory for the NTB–N phase transition. Phys Chem Chem Phys 2016; 18:4394-404. [DOI: 10.1039/c5cp07605f] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have developed a Landau model that predicts a first order twist-bend nematic–nematic phase transition.
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Affiliation(s)
- D. O. López
- Grup de Propietats Físiques dels Materials (GRPFM-GCMM)
- Departament de Física
- E.T.S.E.I.B
- Universitat Politècnica de Catalunya
- 647 08028 Barcelona
| | - B. Robles-Hernández
- Grup de Propietats Físiques dels Materials (GRPFM-GCMM)
- Departament de Física
- E.T.S.E.I.B
- Universitat Politècnica de Catalunya
- 647 08028 Barcelona
| | - J. Salud
- Grup de Propietats Físiques dels Materials (GRPFM-GCMM)
- Departament de Física
- E.T.S.E.I.B
- Universitat Politècnica de Catalunya
- 647 08028 Barcelona
| | - M. R. de la Fuente
- Departamento de Física Aplicada II
- Facultad de Ciencia y Tecnología
- Universidad del País Vasco
- E-48080 Bilbao
- Spain
| | - N. Sebastián
- Institute for Experimental Physics
- Otto-von-Guerike Universität Magdeburg
- ANP
- 39106 Magdeburg
- Germany
| | - S. Diez-Berart
- Grup de Propietats Físiques dels Materials (GRPFM-GCMM)
- Departament de Física
- E.T.S.E.I.B
- Universitat Politècnica de Catalunya
- 647 08028 Barcelona
| | - X. Jaen
- Grup de Propietats Físiques dels Materials (GRPFM-GCMM)
- Departament de Física
- E.T.S.E.I.B
- Universitat Politècnica de Catalunya
- 647 08028 Barcelona
| | - D. A. Dunmur
- School of Physics and Astronomy
- University of Manchester
- Manchester M13 9PL
- UK
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24
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Yoshizawa A, Kato Y, Sasaki H, Takanishi Y, Yamamoto J. Chiral conglomerates observed for a binary mixture of a nematic liquid crystal trimer and 6OCB. SOFT MATTER 2015; 11:8827-8833. [PMID: 26395546 DOI: 10.1039/c5sm02121a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Dark conglomerates of domains with opposite handedness, which are designated as dark conglomerate phases (DC phases), have attracted much attention. After designing an achiral liquid crystal trimer, 4,4′-bis{7-[4-(5-octyloxypyrimidin-2-yl)phenyloxy]heptyloxy}biphenyl (1), which exhibits only a nematic phase, we prepared binary mixtures with some typical rod-like nematic liquid crystals, i.e., 4′-hexyloxy-4-cyanobiphenyl (6OCB), 2-(4-hexyloxyphenyl)-5-pentyloxypyrimidine (PPY), or 4-methyloxyphenyl 4-hexyloxycyclohexanecarboxylate (PCA), and investigated their phase transition behaviour. The binary mixtures containing 55–90 mol% of 6OCB were found to exhibit a nematic phase and a DC phase of chiral domains with opposite handedness. However, neither PPY nor PCA induced such a chiral conglomerate phase in the mixture with trimer 1. We discuss how core–core interactions contribute to produce such a chiral conglomerate phase.
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Affiliation(s)
- Atsushi Yoshizawa
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
| | - Yusuke Kato
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
| | - Haruna Sasaki
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
| | - Yoichi Takanishi
- Department of Physics, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto, 606-8562, Japan
| | - Jun Yamamoto
- Department of Physics, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto, 606-8562, Japan
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25
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Dressel C, Weissflog W, Tschierske C. Spontaneous mirror symmetry breaking in a re-entrant isotropic liquid. Chem Commun (Camb) 2015; 51:15850-3. [PMID: 26376587 DOI: 10.1039/c5cc06843f] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An achiral double-swallow tailed tetracatenar compound forms a re-entrant isotropic liquid between a bicontinuous cubic phase and a nematic liquid crystalline phase. This isotropic liquid was found to represent a conglomerate of two immiscible chiral liquids. The chirality is retained and eventually becomes uniform at the transition to the cubic I432 phase.
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Affiliation(s)
- Christian Dressel
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str.2, D-06120 Halle/Saale, Germany.
| | - Wolfgang Weissflog
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str.2, D-06120 Halle/Saale, Germany.
| | - Carsten Tschierske
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str.2, D-06120 Halle/Saale, Germany.
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26
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Alaasar M, Prehm M, Cao Y, Liu F, Tschierske C. Spontaneous Mirror-Symmetry Breaking in Isotropic Liquid Phases of Photoisomerizable Achiral Molecules. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201508097] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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27
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Tschierske C, Ungar G. Mirror Symmetry Breaking by Chirality Synchronisation in Liquids and Liquid Crystals of Achiral Molecules. Chemphyschem 2015; 17:9-26. [DOI: 10.1002/cphc.201500601] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Indexed: 01/05/2023]
Affiliation(s)
- Carsten Tschierske
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
| | - Goran Ungar
- Department of Physics; Zhejiang Sci-Tech University; Xiasha College Park 310018 Hangzhou China
- Department of Materials Science and Engineering; University of Sheffield; Sheffield S1 3JD Sheffield UK
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28
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Tavarone R, Charbonneau P, Stark H. Phase ordering of zig-zag and bow-shaped hard needles in two dimensions. J Chem Phys 2015; 143:114505. [DOI: 10.1063/1.4930886] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Raffaele Tavarone
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - Patrick Charbonneau
- Departments of Chemistry and Physics, Duke University, Durham, North Carolina 27708, USA
| | - Holger Stark
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
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29
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Piccionello AP, Calabrese A, Pibiri I, Giacalone V, Pace A, Buscemi S. Synthesis of Fluorinated Bent-Core Mesogens (BCMs) Containing the 1,2,4-Oxadiazole Ring. J Heterocycl Chem 2015. [DOI: 10.1002/jhet.2509] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Antonio Palumbo Piccionello
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche; Università di Palermo; Viale delle Scienze, ed. 17 90128 Palermo Italy
- Istituto Euro-mediterraneo di scienza e Tecnologia, IEMEST; Via E. Amari 123 90145 Palermo Italy
| | - Alessandro Calabrese
- ENEA UTTRI-Ufficio territoriale della Sicilia-via Principe di Granatelli 24; 90139 Palermo Italy
| | - Ivana Pibiri
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche; Università di Palermo; Viale delle Scienze, ed. 17 90128 Palermo Italy
- Istituto Euro-mediterraneo di scienza e Tecnologia, IEMEST; Via E. Amari 123 90145 Palermo Italy
| | - Valentina Giacalone
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche; Università di Palermo; Viale delle Scienze, ed. 17 90128 Palermo Italy
| | - Andrea Pace
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche; Università di Palermo; Viale delle Scienze, ed. 17 90128 Palermo Italy
- Istituto Euro-mediterraneo di scienza e Tecnologia, IEMEST; Via E. Amari 123 90145 Palermo Italy
| | - Silvestre Buscemi
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche; Università di Palermo; Viale delle Scienze, ed. 17 90128 Palermo Italy
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30
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Alaasar M, Prehm M, Brautzsch M, Tschierske C. Dark conglomerate phases of azobenzene derived bent-core mesogens - relationships between the molecular structure and mirror symmetry breaking in soft matter. SOFT MATTER 2014; 10:7285-7296. [PMID: 25095778 DOI: 10.1039/c4sm01255k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
New 4-bromoresorcinol based bent-core molecules with peripheral fluoro substituted azobenzene wings have been synthesized and the liquid crystalline self-assembly was investigated by differential scanning calorimetry (DSC), optical polarizing microscopy (POM), electro-optic studies and X-ray diffraction (XRD). A new type of optically isotropic mesophase composed of chiral domains with opposite handedness (dark conglomerate phases, DC phases) is observed, which for some homologues with medium alkyl chain length is stable down to ambient temperature. It is proposed that these DC phases are formed by helical twisted nano-domains of limited size and composed of the crystallized aromatic cores which are separated by the disordered alkyl chains. This structure is distinct from the previously known soft helical nano-filament phases (HNF phases, B4 phases) formed by extended crystalline nano-filaments and also distinct from the fluid sponge phases composed of deformed fluid layers. Comparison with related bent-core molecules having H, F, Cl, I, CH3 and CN groups in the 4-position at the resorcinol core, either with or without additional peripheral fluorines, provided information about the effects of these substituents on the tendency to form DC phases. Based on these relationships and by comparison with the minimum energy conformations obtained by DFT calculations a hypothesis is provided for the formation of DC phases depending on the molecular structure.
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Affiliation(s)
- Mohamed Alaasar
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt Mothes Str. 2, D-06120 Halle (Saale), Germany.
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31
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Dressel C, Reppe T, Prehm M, Brautzsch M, Tschierske C. Chiral self-sorting and amplification in isotropic liquids of achiral molecules. Nat Chem 2014; 6:971-7. [DOI: 10.1038/nchem.2039] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 07/23/2014] [Indexed: 01/30/2023]
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32
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Paul MK, Kalita G, Laskar AR, Debnath S, Gude V, Sarkar DD, Mohiuddin G, Varshney SK, Nandiraju Rao V. Synthesis and mesomorphic behaviour of achiral four-ring unsymmetrical bent-core liquid crystals: Nematic phases. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.06.044] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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33
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Tschierske C. Entwicklung struktureller Komplexität durch Selbstorganisation in flüssigkristallinen Systemen. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201300872] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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34
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Meyer C, Luckhurst GR, Dozov I. Flexoelectrically driven electroclinic effect in the twist-bend nematic phase of achiral molecules with bent shapes. PHYSICAL REVIEW LETTERS 2013; 111:067801. [PMID: 23971614 DOI: 10.1103/physrevlett.111.067801] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Indexed: 06/02/2023]
Abstract
We extend the twist-bend nematic (N(TB)) model to describe the electro-optics of this novel phase. We predict an electroclinic effect (ECE) subject to a dc electric field E applied perpendicular to the helix axis or wave vector q, with rotation of the N(TB) optic axis around E. This linear effect, with its flexoelectric origin, is a close analog to the electro-optic effects observed for chiral liquid crystals. However, in nematics composed of achiral molecules having a bent shape, it is the electro-optic signature of the N(TB) phase. We test our model experimentally in the low-temperature nematic phase of the odd liquid crystal dimer, CB7CB, with its molecules having, on average, a bent shape. The ECE measurements confirm the previously proposed twist-bend nematic structure of this phase, with its broken chiral symmetry, extremely short (<10 nm) doubly degenerate pitch and ultrafast, submicrosecond response times.
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Affiliation(s)
- C Meyer
- Physique des Systèmes Complexes, Université de Picardie Jules Verne, 80039 Amiens, France
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35
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Tschierske C. Development of structural complexity by liquid-crystal self-assembly. Angew Chem Int Ed Engl 2013; 52:8828-78. [PMID: 23934786 DOI: 10.1002/anie.201300872] [Citation(s) in RCA: 349] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Indexed: 11/09/2022]
Abstract
Since the discovery of the liquid-crystalline state of matter 125 years ago, this field has developed into a scientific area with many facets. This Review presents recent developments in the molecular design and self-assembly of liquid crystals. The focus is on new exciting soft-matter structures distinct from the usually observed nematic, smectic, and columnar phases. These new structures have enhanced complexity, including multicompartment and cellular structures, periodic and quasiperiodic arrays of spheres, and new emergent properties, such as ferroelctricity and spontaneous achiral symmetry-breaking. Comparisons are made with developments in related fields, such as self-assembled monolayers, multiblock copolymers, and nanoparticle arrays. Measures of structural complexity used herein are the size of the lattice, the number of distinct compartments, the dimensionality, and the logic depth of the resulting supramolecular structures.
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Affiliation(s)
- Carsten Tschierske
- Institut für Chemie, Organische Chemie, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle Saale, Germany.
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36
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Adlem K, Čopič M, Luckhurst GR, Mertelj A, Parri O, Richardson RM, Snow BD, Timimi BA, Tuffin RP, Wilkes D. Chemically induced twist-bend nematic liquid crystals, liquid crystal dimers, and negative elastic constants. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:022503. [PMID: 24032852 DOI: 10.1103/physreve.88.022503] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Indexed: 06/02/2023]
Abstract
Here we report the chemical induction of the twist-bend nematic phase in a nematic mixture of ether-linked liquid crystal dimers by the addition of a dimer with methylene links; all dimers have an odd number of groups in the spacer connecting the two mesogenic groups. The twist-bend phase has been identified from its optical texture and x-ray scattering pattern as well as NMR spectroscopy, which demonstrates the phase chirality. Theory predicts that the key macroscopic property required for the stability of this chiral phase formed from achiral molecules is for the bend elastic constant to tend to be negative; in addition the twist elastic constant should be smaller than half the splay elastic constant. To test these important aspects of the prediction we have measured the bend and splay elastic constants in the nematic phase preceding the twist-bend nematic using the classic Frederiks methodology and all three elastic constants employing the dynamic light scattering approach. Our results show that, unlike the splay, the bend elastic constant is small and decreases significantly as the transition to the induced twist-bend nematic phase is approached, but then exhibits unexpected behavior prior to the phase transition.
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Affiliation(s)
- K Adlem
- Merck Chemicals Ltd., Chilworth Technical Centre, University Parkway, Southampton SO16 7QD, United Kingdom
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37
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Emsley JW, Lelli M, Lesage A, Luckhurst GR. A comparison of the conformational distributions of the achiral symmetric liquid crystal dimer CB7CB in the achiral nematic and chiral twist-bend nematic phases. J Phys Chem B 2013; 117:6547-57. [PMID: 23634827 DOI: 10.1021/jp4001219] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sets of residual dipolar couplings between carbon and hydrogen nuclei obtained from the proton-encoded (13)C 2D NMR experiment are used to investigate the conformational changes which occur when the achiral symmetric liquid crystal dimer CB7CB changes from the achiral nematic to the chiral twist-bend nematic phase. It is found that these changes are a consequence of the chirality of the twist-bend nematic phase, rather than being the driving force for the stability of this phase.
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Affiliation(s)
- James W Emsley
- Centre RMN à Très Hauts Champs, CNRS/ENS Lyon/UCB-Lyon 1, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France.
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38
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Alaasar M, Prehm M, Nagaraj M, Vij JK, Tschierske C. A liquid crystalline phase with uniform tilt, local polar order and capability of symmetry breaking. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:2186-2191. [PMID: 23427137 DOI: 10.1002/adma.201205180] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Indexed: 06/01/2023]
Abstract
A new liquid crystalline (LC) phase with uniform tilt, local polar order and capability of symmetry breaking is found for a bent-core mesogen combining a 4-cyanoresorcinol unit with two azobenzene wings. The combination of local polar order and long range synclinic tilt in this SmC(s)P(R) phase leads, under special conditions, to macroscopic domains with opposite chirality, though the molecules themselves are achiral.
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Affiliation(s)
- Mohamed Alaasar
- Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt.
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Emsley JW, Lesot P, Luckhurst GR, Meddour A, Merlet D. Chiral solutes can seed the formation of enantiomorphic domains in a twist-bend nematic liquid crystal. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:040501. [PMID: 23679359 DOI: 10.1103/physreve.87.040501] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Indexed: 06/02/2023]
Abstract
The twist-bend nematic, an enantiomorphic liquid-crystalline phase, exhibited by the structurally symmetric liquid-crystal dimer CB7CB is induced to form a single domain of uniform handedness, in the bulk, by the addition of the dopant chiral solute (S)-1-phenylethanol. Addition of a nonracemic (or scalemic) mixture of both R and S enantiomers of this solute produced equal volumes of P and M chiral domains for the twist-bend nematic phase. This seeding of the domains in an enantiomorphic nematic conglomerate is revealed using deuterium NMR spectroscopy.
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Affiliation(s)
- James W Emsley
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
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Upadhyaya K, Gude V, Mohiuddin G, Nandiraju RVS. A new family of four-ring bent-core nematic liquid crystals with highly polar transverse and end groups. Beilstein J Org Chem 2013; 9:26-35. [PMID: 23400045 PMCID: PMC3566756 DOI: 10.3762/bjoc.9.4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/29/2012] [Indexed: 11/23/2022] Open
Abstract
Non-symmetrically substituted four-ring achiral bent-core compounds with polar substituents, i.e.., chloro in the bent or transverse direction in the central core and cyano in the lateral direction at one terminal end of the molecule, are designed and synthesized. These molecules possess an alkoxy chain attached at only one end of the bent-core molecule. The molecular structure characterization is consistent with data from elemental and spectroscopic analysis. The materials thermal behaviour and phase characterization have been investigated by differential scanning calorimetry and polarizing microscopy. All the compounds exhibit a wide-ranging monotropic nematic phase.
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Affiliation(s)
- Kalpana Upadhyaya
- Chemistry Department, Assam University, Silchar-788011, Assam, India, phone 919435522541, fax 913842270806
| | - Venkatesh Gude
- Chemistry Department, Assam University, Silchar-788011, Assam, India, phone 919435522541, fax 913842270806
| | - Golam Mohiuddin
- Chemistry Department, Assam University, Silchar-788011, Assam, India, phone 919435522541, fax 913842270806
| | - Rao V S Nandiraju
- Chemistry Department, Assam University, Silchar-788011, Assam, India, phone 919435522541, fax 913842270806
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Deb R, Laskar AR, Sarkar DD, Mohiuddin G, Chakraborty N, Ghosh S, Shankar Rao DS, Rao NVS. Fluorescent unsymmetrical four-ring bent-core mesogens: 2D modulated phases. CrystEngComm 2013. [DOI: 10.1039/c3ce41360h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Alaasar M, Prehm M, Tschierske C. A new room temperature dark conglomerate mesophase formed by bent-core molecules combining 4-iodoresorcinol with azobenzene units. Chem Commun (Camb) 2013; 49:11062-4. [DOI: 10.1039/c3cc45938a] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Tadapatri P, Krishnamurthy KS. Competing Instability Modes in an Electrically Driven Bent-Core Nematic Liquid Crystal. J Phys Chem B 2012; 116:782-93. [DOI: 10.1021/jp210383p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pramod Tadapatri
- Centre for Soft Matter Research, P.O. Box 1329, Jalahalli, Bangalore 560013, India
| | - K. S. Krishnamurthy
- Centre for Soft Matter Research, P.O. Box 1329, Jalahalli, Bangalore 560013, India
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Peroukidis SD, Vanakaras AG, Photinos DJ. Molecular simulation of hierarchical structures in bent-core nematic liquid crystals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:010702. [PMID: 21867106 DOI: 10.1103/physreve.84.010702] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Indexed: 05/31/2023]
Abstract
The structure of nematic liquid crystals formed by bent-core mesogens (BCMs) is studied in the context of Monte Carlo simulations of a simple molecular model that captures the symmetry, shape, and flexibility of achiral BCMs. The results indicate the formation of (i) clusters exhibiting local smectic order, orthogonal or tilted, with strong in-layer polar correlations and antiferroelectric juxtaposition of successive layers and (ii) large homochiral domains through the helical arrangement of the tilted smectic clusters, while the orthogonal clusters produce achiral (untwisted) nematic states.
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Tadapatri P, Krishnamurthy KS, Weissflog W. Multiple electroconvection scenarios in a bent-core nematic liquid crystal. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:031706. [PMID: 21230090 DOI: 10.1103/physreve.82.031706] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Indexed: 05/30/2023]
Abstract
We report on the anisotropic electrohydrodynamic states formed over a wide temperature range (∼45 °C) in a planarly aligned bent-core nematic liquid crystal driven by fields of frequency in the range 0.1 Hz-1 MHz. Three different primary bifurcation scenarios are generated in the voltage-frequency (V-f) plane, depending on the temperature T. These, under increasing T, are characterized by the pattern sequences (i) in-plane longitudinal rolls (ILR)→in-plane normal rolls 1 (INR1), (ii) Williams rolls (WR)→ILR→INR1, and (iii) WR→INR2→INR1. Temperature-induced ILR→INR2 transition, the first example of its kind, points to elastic anisotropy as possibly the determining factor in wave vector selection. In the ILR and INR states, at threshold, the director modulations are predominantly azimuthal, and the streamlines, mainly normal to the wave vector, lie in the sample plane. Well above threshold, growing director deviations lead to narrow disclination loops that evolve in regular arrays, with their area density being exponential in voltage. The defects drift in a coordinated manner along the flow lines with a speed that scales nonlinearly with voltage; they mediate in the eventual occurrence of turbulence. The current theories of anisotropic convection based on static electrical parameters fail to account for the observed high-frequency instabilities. The study includes (i) a quantitative characterization of the critical parameter functions V(c)(f), V(c)(T), q(c)(f), and q(c)(T), with q(c) denoting the critical pattern wave number, and (ii) measurement of electrical and elastic parameters of relevance to electroconvection; the latter show anomalous features supporting the cluster hypothesis.
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Affiliation(s)
- Pramod Tadapatri
- Centre for Soft Matter Research, P.O. Box 1329, Jalahalli, Bangalore 560 013, India
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Mukherjee PK. Macroscopic description of the isotropic to antiferroelectric B2 phase transition in banana-shaped liquid crystals. J Chem Phys 2010; 132:024903. [DOI: 10.1063/1.3281640] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Brand HR, Pleiner H. Macroscopic behavior of non-polar tetrahedratic nematic liquid crystals. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 31:37-50. [PMID: 20101516 DOI: 10.1140/epje/i2010-10547-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 10/30/2009] [Accepted: 11/20/2009] [Indexed: 05/28/2023]
Abstract
We discuss the symmetry properties and the macroscopic behavior of a nematic liquid crystal phase with D(2d) symmetry. Such a phase is a prime candidate for nematic phases made from banana-shaped molecules where the usual quadrupolar order coexists with octupolar (tetrahedratic) order. The resulting nematic phase is nonpolar. While this phase could resemble the classic D (infinityh) nematic in the polarizing microscope, it has many static as well as reversible and irreversible properties unknown to nonpolar nematics without octupolar order. In particular, there is a linear gradient term in the free energy that selects parity leading to ambidextrously helical ground states when the molecules are achiral. In addition, there are static and irreversible coupling terms of a type only met otherwise in macroscopically chiral liquid crystals, e.g. the ambidextrous analogues of Lehmann-type effects known from cholesteric liquid crystals. We also discuss the role of hydrodynamic rotations about the nematic director. For example, we show how strong external fields could alter the D(2d) symmetry, and describe the non-hydrodynamic aspects of the dynamics, if the two order structures, the nematic and the tetrahedratic one, rotate relative to each other. Finally, we discuss certain nonlinear aspects of the dynamics related to the non-commutativity of three-dimensional finite rotations as well as other structural nonlinear hydrodynamic effects.
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Affiliation(s)
- H R Brand
- Max-Planck-Institute for Polymer Research, Mainz, Germany.
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