1
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Máthé MT, Nishikawa H, Araoka F, Jákli A, Salamon P. Electrically activated ferroelectric nematic microrobots. Nat Commun 2024; 15:6928. [PMID: 39164266 PMCID: PMC11336208 DOI: 10.1038/s41467-024-50226-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 07/02/2024] [Indexed: 08/22/2024] Open
Abstract
Ferroelectric nematic liquid crystals are fluids exhibiting spontaneous electric polarization, which is coupled to their long range orientational order. Due to their inherent property of making bound and surface charges, the free surface of ferroelectric nematics becomes unstable in electric fields. Here we show that ferroelectric liquid bridges between two electrode plates undergo distinct interfacial instabilities. In a specific range of frequency and voltage, the ferroelectric fluid bridges move as active interacting particles resembling living organisms like swarming insects, microbes or microrobots. The motion is accompanied by sound emission, as a consequence of piezoelectricity and electrostriction. Statistical analysis of the active particles reveals that the movement can be controlled by the applied voltage, which implies the possible application of the system in new types of microfluidic devices.
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Affiliation(s)
- Marcell Tibor Máthé
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, Budapest, Hungary
- Eötvös Loránd University, P.O. Box 32, Budapest, Hungary
| | - Hiroya Nishikawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, Japan
| | - Fumito Araoka
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, Japan.
| | - Antal Jákli
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, Budapest, Hungary.
- Material Science Graduate Program and Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, USA.
- Department of Physics, Kent State University, Kent, OH, USA.
| | - Péter Salamon
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, Budapest, Hungary.
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2
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Ben Salah M, Saadaoui L, Soltani T, Ben Hamadi N, Guesmi A, Maschke U. New Series of Hydrogen-Bonded Liquid Crystal with High Birefringence and Conductivity. Molecules 2024; 29:3422. [PMID: 39065000 PMCID: PMC11279611 DOI: 10.3390/molecules29143422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 07/18/2024] [Accepted: 07/19/2024] [Indexed: 07/28/2024] Open
Abstract
Liquid crystals with high dielectric anisotropy, low operational thresholds, and significant birefringence (Δn) represent a key focus in soft matter research. This work introduces a novel series of hydrogen-bonded liquid crystals (HBLCs) derived from 4-n-alkoxybenzoic, 4-alkoxy-3-fluorobenzoic derivatives (nOBAF), 4-alkoxy-2,3-fluorobenzoic derivatives (nOBAFF), and 2-fluoro-4-nitrobenzoic acid. The HBLCs were characterized using Fourier transform infrared spectroscopy, and their thermal behavior was evaluated via differential scanning calorimetry. Optical observations were conducted using polarized optical microscopy. The results indicate that mixtures containing benzoic acid with a bilateral fluorine substituent exhibit both SmA and SmC phases, while those with a unilateral fluorine substituent exhibit nematic and SmA phases. Moreover, an increase in the length of the alkoxy chain results in an expanded mesophase temperature range. This study demonstrates that the presence of a fluorine substituent and the incorporation of an NO2 group in the molecular structure result in an increase in dielectric permittivity, DC conductivity, dielectric anisotropy, and birefringence.
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Affiliation(s)
- Manel Ben Salah
- Laboratoire de Physique de la Matière Molle et de la Modélisation Electromagnétique, Faculté des Sciences de Tunis, Université de Tunis El Manar, Tunis 2092, Tunisia; (M.B.S.); (T.S.)
| | - Lotfi Saadaoui
- The MOE Key Laboratory of Weak-Light Nonlinear Photonics and International Sino-Slovenian Joint Research Center on Liquid Crystal Photonics, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin 300457, China
| | - Taoufik Soltani
- Laboratoire de Physique de la Matière Molle et de la Modélisation Electromagnétique, Faculté des Sciences de Tunis, Université de Tunis El Manar, Tunis 2092, Tunisia; (M.B.S.); (T.S.)
| | - Naoufel Ben Hamadi
- Chemistry Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), P.O. Box 5701, Riyadh 11432, Saudi Arabia; (N.B.H.); (A.G.)
| | - Ahlem Guesmi
- Chemistry Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), P.O. Box 5701, Riyadh 11432, Saudi Arabia; (N.B.H.); (A.G.)
| | - Ulrich Maschke
- Unité Matériaux et Transformations (UMET), UMR 8207–CNRS, University Lille, CNRS, INRAE, Centrale Lille, F-59000 Lille, France
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3
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Gibb CJ, Hobbs J, Nikolova DI, Raistrick T, Berrow SR, Mertelj A, Osterman N, Sebastián N, Gleeson HF, Mandle RJ. Spontaneous symmetry breaking in polar fluids. Nat Commun 2024; 15:5845. [PMID: 38992039 PMCID: PMC11239904 DOI: 10.1038/s41467-024-50230-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 07/03/2024] [Indexed: 07/13/2024] Open
Abstract
Spontaneous symmetry breaking and emergent polar order are each of fundamental importance to a range of scientific disciplines, as well as generating rich phase behaviour in liquid crystals (LCs). Here, we show the union of these phenomena to lead to two previously undiscovered polar liquid states of matter. Both phases have a lamellar structure with an inherent polar ordering of their constituent molecules. The first of these phases is characterised by polar order and a local tilted structure; the tilt direction processes about a helix orthogonal to the layer normal, the period of which is such that we observe selective reflection of light. The second new phase type is anti-ferroelectric, with the constituent molecules aligning orthogonally to the layer normal. This has led us to term the phases the Sm C P H and SmAAF phases, respectively. Further to this, we obtain room temperature ferroelectric nematic (NF) and Sm C P H phases via binary mixture formulation of the novel materials described here with a standard NF compound (DIO), with the resultant materials having melting points (and/or glass transitions) which are significantly below ambient temperature. The new soft matter phase types discovered herein can be considered as electrical analogues of topological structures of magnetic spins in hard matter.
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Affiliation(s)
- Calum J Gibb
- School of Chemistry, University of Leeds, Leeds, UK
| | - Jordan Hobbs
- School of Physics and Astronomy, University of Leeds, Leeds, UK
| | | | | | - Stuart R Berrow
- School of Physics and Astronomy, University of Leeds, Leeds, UK
| | | | - Natan Osterman
- Jožef Stefan Institute, Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
| | | | - Helen F Gleeson
- School of Physics and Astronomy, University of Leeds, Leeds, UK
| | - Richard J Mandle
- School of Chemistry, University of Leeds, Leeds, UK.
- School of Physics and Astronomy, University of Leeds, Leeds, UK.
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4
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Perkowski P, Urbańska M. Dielectric Modes in Antiferroelectric and Ferroelectric Liquid Crystals in a Pure Enantiomeric Version and a Racemic Mixture. MATERIALS (BASEL, SWITZERLAND) 2024; 17:3335. [PMID: 38998416 PMCID: PMC11243658 DOI: 10.3390/ma17133335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/12/2024] [Accepted: 06/17/2024] [Indexed: 07/14/2024]
Abstract
The dielectric properties of synclinic (ferroelectric SmC*) and anticlinic (antiferroelectric SmCA*) smectic liquid crystals composed of molecules of one chiral version (S) are presented and compared with properties of racemic mixture (R, S), showing SmC and SmCA phases. The racemic mixture completely loses its ferroelectric and antiferroelectric properties. Surprisingly, only one dielectric mode observed in the antiferroelectric SmCA* phase disappeared in the dielectric response of the racemic SmCA phase. Additionally, we observed that in the SmC phase, seen in the racemic mixture, the weak dielectric mode (named the X mode) is detected, which seems to be the continuation of the PL mode existing in the racemic SmCA. Moreover, this mode in the racemic SmC has nothing to do with the Goldstone mode, typical for the SmC* phase. This paper describes in detail the real and imaginary parts of dielectric permittivity in smectic phases for the enantiomer and racemate with and without a DC field, compares the properties of the X and PL modes, and discusses the full scheme of dielectric modes in enantiomer and racemate.
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Affiliation(s)
- Paweł Perkowski
- Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland
| | - Magdalena Urbańska
- Institute of Chemistry, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland;
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5
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Nacke P, Tuffin R, Klasen-Memmer M, Rudquist P, Giesselmann F. Revealing the antipolar order in the antiferroelectric SmZ A phase by means of circular alignment. Sci Rep 2024; 14:15018. [PMID: 38951542 PMCID: PMC11217385 DOI: 10.1038/s41598-024-65275-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/18/2024] [Indexed: 07/03/2024] Open
Abstract
Many ferroelectric nematic liquid crystals, like one of the archetype materials, DIO, do not have a direct paraelectric N to ferroelectric NF phase transition, but exhibit yet another phase between N and NF. This phase has recently been proposed to be antiferroelectric, with a layered structure of alternating polarization normal to the average director and is sometimes referred to as Smectic ZA (SmZA). We have examined the SmZA phase in circularly rubbed (CR) cells, known to discriminate between the polar NF and the non-polar N phase from the configuration of disclination lines formed. We find that the ground state of SmZA has the same disclination configuration as the non-polar N phase, demonstrating that the SmZA phase is also non-polar, i.e., it has no net ferroelectric polarization. At the same time, the SmZA texture generally has a grainy appearance, which we suggest is partly a result of the frustration related to layered order combined with the imposed twist in CR cells. We discuss possible orientations of the smectic layers, depending on the alignment conditions. While a horizontal SmZA layer structure is always compatible with surface-induced twist, a vertical layer structure would tend to break up in a twisted bookshelf structure to match non-parallel alignment directions at the two surfaces.
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Affiliation(s)
- Pierre Nacke
- Institute of Physical Chemistry, University of Stuttgart, 70569, Stuttgart, Germany
| | - Rachel Tuffin
- Display Solutions, Merck Electronics KGaA, 64293, Darmstadt, Germany
| | | | - Per Rudquist
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296, Gothenburg, Sweden.
| | - Frank Giesselmann
- Institute of Physical Chemistry, University of Stuttgart, 70569, Stuttgart, Germany.
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6
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Pleiner H, Brand HR. Macroscopic dynamics of ferromagnetic smectic-A. Phys Rev E 2024; 109:064612. [PMID: 39021036 DOI: 10.1103/physreve.109.064612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 06/03/2024] [Indexed: 07/20/2024]
Abstract
We derive the macroscopic dynamic equations for ferromagnetic smectic-A liquid crystals for which the spontaneous magnetization is parallel to the layer normal of the layering. As additional macroscopic variables when compared to simple fluids, we have the layer displacement u, familiar from smectic liquid crystals, and the magnetization density M. We find a number of reversible and dissipative cross-coupling terms to the additional macroscopic variables and discuss possible experiments to detect them. Among other effects, we point out that the velocity of first sound becomes anisotropic due to the influence of the modulus of the magnetization, while the magnitude of the velocity of second sound is modified. As for the static behavior, we find cross-coupling terms between the magnitude of the magnetization, on the one hand, and layer compression as well as osmotic pressure, on the other hand. In addition, we point out that as a dissipative effect, temperature gradients can induce gradients in the magnetization parallel to the layer normal, mediated by layer compressions.
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7
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Cruickshank E. The Emergence of a Polar Nematic Phase: A Chemist's Insight into the Ferroelectric Nematic Phase. Chempluschem 2024; 89:e202300726. [PMID: 38452282 DOI: 10.1002/cplu.202300726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/20/2024] [Accepted: 03/07/2024] [Indexed: 03/09/2024]
Abstract
The discovery of a new polar nematic phase; the ferroelectric nematic, has generated a great deal of excitement in the field of liquid crystals. To date there have been around 150 materials reported exhibiting the ferroelectric nematic phase, in general, following three key archetypal structures with these compounds known as RM734, DIO and UUQU-4N. In this review, the relationship between the molecular structure and the stability of the ferroelectric nematic, NF, phase will be described from a chemist's perspective. This will look to highlight the wide variety of functionalities which have been incorporated into these archetypal structures and how these changes influence the transition temperatures of the mesophases present. The NF phase appears to be stabilised particularly by reducing the length of terminal alkyl chains present and adding fluorines laterally along the length of the molecular backbone. This review will look to introduce the background of the ferroelectric nematic phase before then showing the molecular structures of a range of materials which exhibit the phase, describing their structure-property relationships and therefore giving an up-to-date account of the literature for this fascinating new mesophase.
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Affiliation(s)
- Ewan Cruickshank
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB10 7GJ, UK
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8
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Aya S, Xu H, Long H, Yiliu M, Zou Y, Huang M. Response of helielectric nematics under an in-plane electric field. Phys Chem Chem Phys 2024; 26:12422-12432. [PMID: 38619386 DOI: 10.1039/d4cp00588k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
In traditional chiral nematic liquid crystals, the apolar cholesterics, the dielectric effect is the main driving force for responding to an electric field. The emerging polar chiral nematics, dubbed helielectric nematics, are the polar counterparts of the cholesterics. The head-to-tail symmetry breaking of the new matter state enables it to respond sensitively to the polarity of an electric field. Here, we report on the observation of a sequential polar winding/unwinding process of polarization helices under an electric field applied perpendicular to the helical axes, which behaves distinctly from the unwinding of the apolar cholesteric helices. Understanding the helix-unwinding behaviors provides insights for developing switchable devices based on helielectric nematics.
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Affiliation(s)
- Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Hao Xu
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Huaqian Long
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Muhan Yiliu
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Yu Zou
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Mingjun Huang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
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9
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Nacke P, Manabe A, Klasen-Memmer M, Chen X, Martinez V, Freychet G, Zhernenkov M, Maclennan JE, Clark NA, Bremer M, Giesselmann F. New examples of ferroelectric nematic materials showing evidence for the antiferroelectric smectic-Z phase. Sci Rep 2024; 14:4473. [PMID: 38396051 PMCID: PMC11319781 DOI: 10.1038/s41598-024-54832-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 02/16/2024] [Indexed: 02/25/2024] Open
Abstract
We present a new ferroelectric nematic material, 4-((4'-((trans)-5-ethyloxan-2-yl)-2',3,5,6'-tetrafluoro-[1,1'-biphenyl]-4-yl)difluoromethoxy)-2,6-difluorobenzonitrile (AUUQU-2-N) and its higher homologues, the molecular structures of which include fluorinated building blocks, an oxane ring, and a terminal cyano group, all contributing to a large molecular dipole moment of about 12.5 D. We observed that AUUQU-2-N has three distinct liquid crystal phases, two of which were found to be polar phases with a spontaneous electric polarization Ps of up to 6 µC cm-2. The highest temperature phase is a common enantiotropic nematic (N) exhibiting only field-induced polarization. The lowest-temperature, monotropic phase proved to be a new example of the ferroelectric nematic phase (NF), evidenced by a single-peak polarization reversal current response, a giant imaginary dielectric permittivity on the order of 103, and the absence of any smectic layer X-ray diffraction peaks. The ordinary nematic phase N and the ferroelectric nematic phase NF are separated by an antiferroelectric liquid crystal phase which has low permittivity and a polarization reversal current exhibiting a characteristic double-peak response. In the polarizing light microscope, this antiferroelectric phase shows characteristic zig-zag defects, evidence of a layered structure. These observations suggest that this is another example of the recently discovered smectic ZA (SmZA) phase, having smectic layers with the molecular director parallel to the layer planes. The diffraction peaks from the smectic layering have not been observed to date but detailed 2D X-ray studies indicate the presence of additional short-range structures including smectic C-type correlations in all three phases-N, SmZA and NF-which may shed new light on the understanding of polar and antipolar order in these phases.
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Affiliation(s)
- Pierre Nacke
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Atsutaka Manabe
- Display Solutions, Merck Electronics KGaA, 64293, Darmstadt, Germany
- Individual researcher (Since 01.01.22), 64625, Bensheim, Germany
| | | | - Xi Chen
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
| | - Vikina Martinez
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
| | - Guillaume Freychet
- Brookhaven National Laboratory, National Synchrotron Light Source-II, Upton, NY, 11973, USA
| | - Mikhail Zhernenkov
- Brookhaven National Laboratory, National Synchrotron Light Source-II, Upton, NY, 11973, USA
| | - Joseph E Maclennan
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
| | - Noel A Clark
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
| | - Matthias Bremer
- Display Solutions, Merck Electronics KGaA, 64293, Darmstadt, Germany
| | - Frank Giesselmann
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
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10
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Brand HR, Pleiner H. Macroscopic dynamics of the ferroelectric smectic [Formula: see text] phase with [Formula: see text] symmetry. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2024; 47:10. [PMID: 38305841 PMCID: PMC11226535 DOI: 10.1140/epje/s10189-024-00406-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 01/05/2024] [Indexed: 02/03/2024]
Abstract
We present the macroscopic dynamics of ferroelectric smectic A, smectic [Formula: see text], liquid crystals reported recently experimentally by three groups. In this fluid and orthogonal smectic phase, the macroscopic polarization, [Formula: see text], is parallel to the layer normal thus giving rise to [Formula: see text] overall symmetry for this phase in the spatially homogeneous limit. A combination of linear irreversible thermodynamics and symmetry arguments is used to derive the resulting dynamic equations applicable at sufficiently low frequencies and sufficiently long wavelengths. Compared to non-polar smectic A phases, we find a static cross-coupling between compression of the layering and bending of the layers, which does not lead to elastic forces, but to elastic stresses. In addition, it turns out that a reversible cross-coupling between flow and the magnitude of the polarization modifies the velocities of both, first and second sound. At the same time, the relaxation of the polarization gives rise to dissipative effects for second sound at the same order of the wavevector as for the sound velocity. We also analyze reversible cross-coupling terms between elongational flow and electric fields as well as temperature and concentration gradients, which lend themselves to experimental detection. Apparently this type of terms has never been considered before for smectic phases. The question how the linear [Formula: see text] coupling in the energy alters the macroscopic response behavior when compared to usual non-polar smectic A phases is also addressed.
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Affiliation(s)
- Helmut R Brand
- Department of Physics, University of Bayreuth, 95440, Bayreuth, Germany
| | - Harald Pleiner
- Max Planck Institute for Polymer Research, 55021, Mainz, Germany.
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11
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Barthakur A, Bag B, Shivaraja SJ, Karcz J, Kula P, Dhara S. Mixing twist-bend and ferroelectric nematic liquid crystals. Phys Rev E 2024; 109:024702. [PMID: 38491706 DOI: 10.1103/physreve.109.024702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 01/12/2024] [Indexed: 03/18/2024]
Abstract
Twist-bend (N_{tb}) and ferroelectric (N_{F}) nematic liquid crystals exhibit several novel effects and new physical properties. Here, we report experimental studies on the phase diagram and some physical properties of binary mixtures of CB9CB and RM734 mesogens. Both N-N_{tb} and N-N_{F} phase transition temperatures and the corresponding enthalpies decrease significantly and, eventually, these transitions disappear at some intermediate compositions, stabilizing wide nematic phase (N). Temperature-dependent birefringence several degrees above the N-N_{tb} phase transition shows strong director tilt fluctuations. The critical range of the fluctuations increases with the nematic range and the critical exponent is consistent with the mean field. The spontaneous polarization of RM734 decreases drastically with the addition of CB9CB mesogen. The temperature dependence of the splay elastic constant of the mixtures' high-temperature nematic (N) phase strikingly differs from that of the pristine CB9CB and RM734 mesogens. The study shows that a small inclusion of either compound has a substantial effect on the phase diagram and physical properties.
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Affiliation(s)
| | - Bidisha Bag
- School of Physics, University of Hyderabad, Hyderabad 500046, India
| | | | - Jakub Karcz
- Institute of Chemistry, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Warsaw 00-908, Poland
| | - Przemyslaw Kula
- Institute of Chemistry, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Warsaw 00-908, Poland
| | - Surajit Dhara
- School of Physics, University of Hyderabad, Hyderabad 500046, India
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12
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Parton-Barr C, Gleeson HF, Mandle RJ. Room-temperature ferroelectric nematic liquid crystal showing a large and diverging density. SOFT MATTER 2024; 20:672-680. [PMID: 38164818 DOI: 10.1039/d3sm01282d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
The ferroelectric nematic phase (NF) is a recently discovered phase of matter in which the orientational order of the conventional nematic liquid crystal state is augmented with polar order. Atomistic simulations suggest that the polar NF phase would be denser than conventional nematics owing to contributions from polar order. Using an oscillating U-tube densitometer, we obtain detailed temperature-dependent density values for a selection of conventional liquid crystals with excellent agreement with earlier reports. Having demonstrated the validity of our method, we then record density as a function of temperature for M5, a novel room-temperature ferroelectric nematic material. We present the first experimental density data for a NF material as well as density data for a nematic that has not previously been reported. We find that the room-temperature NF material shows a large (>1.3 g cm-3) density at all temperatures studied, notably including phases without polar order. An increase in density at phase transitions is observed. The magnitude of the increase for the intermediate-to-ferroelectric nematic (NX-NF) transition is an order of magnitude smaller than the isotropic-nematic (I-N) transition. We then probe potential consequences that may result from an elevated density through measurement of the refractive indices (no and ne). The navg of M5 is compared with 5CB and polar smectic liquid crystals. We observe how the highly polar nature of the system counteracts the effects of an increase in density. With knowledge of experimental density, we are able to derive an approximation that yields the polar order parameter, 〈P1〉, from polarisation measurements. Present results may be typical of ferroelectric nematic materials, potentially guiding material development, and is especially relevant for informing ongoing studies into this emerging class of materials.
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Affiliation(s)
| | - Helen F Gleeson
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Richard J Mandle
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
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13
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Emelyanenko AV, Rudyak VY, Shvetsov SA, Araoka F, Nishikawa H, Ishikawa K. Transformation of polar nematic phases in the presence of an electric field. Phys Rev E 2024; 109:014701. [PMID: 38366416 DOI: 10.1103/physreve.109.014701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 12/07/2023] [Indexed: 02/18/2024]
Abstract
Only a few years have passed since the discovery of polar nematics, and now they are becoming the most actively studied liquid-crystal materials. Despite numerous breakthrough findings made recently, a theoretical systematization is still lacking. In the present paper, we take a step toward systematization. The powerful technique of molecular-statistical physics has been applied to an assembly of polar molecules influenced by electric field. Three polar nematic phases were found to be stable at various conditions: the double-splay ferroelectric nematic N_{F}^{2D} (observed in the lower-temperature range in the absence of or at low electric field), the double-splay antiferroelectric nematic N_{AF} (observed at intermediate temperature in the absence of or at low electric field), and the single-splay ferroelectric nematic N_{F}^{1D} (observed at moderate electric field at any temperature below transition into paraelectric nematic N and in the higher-temperature range (also below N) at low electric field or without it. A paradoxical transition from N_{F}^{1D} to N induced by application of higher electric field has been found and explained. A transformation of the structure of polar nematic phases at the application of electric field has also been investigated by Monte Carlo simulations and experimentally by observation of polarizing optical microscope images. In particular, it has been realized that, at planar anchoring, N_{AF} in the presence of a moderate out-of-plane electric field exhibits twofold splay modulation: antiferroelectric in the plane of the substrate and ferroelectric in the plane normal to the substrate. Several additional subtransitions related to fitting the confined geometry of the cell by the structure of polar phases were detected.
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Affiliation(s)
| | - V Yu Rudyak
- Lomonosov Moscow State University, Moscow 119991, Russia
| | - S A Shvetsov
- Lomonosov Moscow State University, Moscow 119991, Russia
| | - F Araoka
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa Wako, Saitama 351-0198, Japan
| | - H Nishikawa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa Wako, Saitama 351-0198, Japan
| | - K Ishikawa
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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14
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Karcz J, Rychłowicz N, Czarnecka M, Kocot A, Herman J, Kula P. Enantiotropic ferroelectric nematic phase in a single compound. Chem Commun (Camb) 2023. [PMID: 37937977 DOI: 10.1039/d3cc04296k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
The ferroelectric nematic phase became the centre of interest of scientists because of its unique physical properties. The uniqueness of this particular phase results in its monotropic character in all known NF materials. Here we present the very first example of a compound with an enantiotropic ferroelectric nematic phase. Compound 3JK is complementary with already well known NF materials, i.e. RM734 and DIO and is characterized by moderately high dielectric anisotropy.
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Affiliation(s)
- Jakub Karcz
- Institute of Chemistry, Faculty of Advanced Technologies and Chemistry, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Natan Rychłowicz
- Institute of Chemistry, Faculty of Advanced Technologies and Chemistry, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Małgorzata Czarnecka
- Faculty of Electrical Engineering, Automatics, Computer Science and Biomedical Engineering, AGH University of Science and Technology, al. Adama Mickiewicza 30, 30-059 Cracow, Poland
| | - Antoni Kocot
- Institute of Materials Engineering, Faculty of Science and Technology, University of Silesia, ul. 75 Pułku Piechoty, 41-500 Chorzów, Poland
| | - Jakub Herman
- Institute of Chemistry, Faculty of Advanced Technologies and Chemistry, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Przemysław Kula
- Institute of Chemistry, Faculty of Advanced Technologies and Chemistry, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw, Poland.
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15
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Ortega J, Folcia CL, Etxebarria J. Second harmonic generation in anisotropic stratified media: a generalization of the Berreman method and its application to photonic materials. OPTICS EXPRESS 2023; 31:36966-36980. [PMID: 38017835 DOI: 10.1364/oe.497447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 10/09/2023] [Indexed: 11/30/2023]
Abstract
We have developed a numerical method for calculating the second-harmonic generation (SHG) generated by an anisotropic material whose optical properties present an arbitrary modulation in one dimension. The method is based on the Berreman 4 × 4 matrix formalism, which is generalized to include nonlinear optical phenomena. It can be used under oblique incidences of the input beam, and is valid even when the SHG frequency is close to photonic bands, where the usual slowly-varying-amplitude approximation breaks down. As an example of application, we have studied the SHG performance of ferroelectric and helielectric fluids. The obtained results indicate that the present procedure may contribute to improving the structural design and enlarging the variety of nonlinear optical materials for application in optical devices.
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16
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Kubala P, Cieśla M. Splay and polar order in a system of hard pear-like molecules: confrontation of Monte Carlo numerical simulations with density functional theory calculations. SOFT MATTER 2023; 19:7836-7845. [PMID: 37800190 DOI: 10.1039/d3sm01021j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Recent experimental discoveries of novel nematic types with polar order, including ferroelectric nematic and splay nematic, have brought the resurgence of the interest in polar and modulated phases. One of the most important factors that is widely believed to be crucial for the formation of new phases is the pear-like shape of mesogenic molecules. Such molecules were treated using second-virial density functional theory in [De Gregorio, P et al., Soft Matter, 2016, 12(23), 5188-5198], where the authors showed that the K11 splay elastic constant can become negative due to solely entropic reasons leading to long-range splay and polar correlations. To verify whether the predictions are correct, we performed Monte Carlo simulations of the same hard-core molecules used in the DFT study. As our results suggest, no polar or modulated liquid crystalline phases emerge; polar and splay correlations are either at most short-range or completely absent. On the other hand, a polar ferroelectric splay crystal was observed.
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Affiliation(s)
- Piotr Kubala
- Institute of Theoretical Physics, Jagiellonian University in Kraków, Łojasiewicza 11, 30-348 Kraków, Poland.
| | - Michał Cieśla
- Institute of Theoretical Physics, Jagiellonian University in Kraków, Łojasiewicza 11, 30-348 Kraków, Poland.
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17
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Cruickshank E, Rybak P, Majewska MM, Ramsay S, Wang C, Zhu C, Walker R, Storey JMD, Imrie CT, Gorecka E, Pociecha D. To Be or Not To Be Polar: The Ferroelectric and Antiferroelectric Nematic Phases. ACS OMEGA 2023; 8:36562-36568. [PMID: 37810647 PMCID: PMC10552116 DOI: 10.1021/acsomega.3c05884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 08/30/2023] [Indexed: 10/10/2023]
Abstract
We report two new series of compounds that show the ferroelectric nematic, NF, phase in which the terminal chain length is varied. The longer the terminal chain, the weaker the dipole-dipole interactions of the molecules are along the director and thus the lower the temperature at which the axially polar NF phase is formed. For homologues of intermediate chain lengths, between the non-polar and ferroelectric nematic phases, a wide temperature range nematic phase emerges with antiferroelectric character. The size of the antiparallel ferroelectric domains critically increases upon transition to the NF phase. In dielectric studies, both collective ("ferroelectric") and non-collective fluctuations are present, and the "ferroelectric" mode softens weakly at the N-NX phase transition because the polar order in this phase is weak. The transition to the NF phase is characterized by a much stronger lowering of the mode relaxation frequency and an increase in its strength, and a typical critical behavior is observed.
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Affiliation(s)
- Ewan Cruickshank
- Department
of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, Aberdeen AB24 3UE, U.K.
| | - Paulina Rybak
- Faculty
of Chemistry, University of Warsaw, ul. Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Magdalena M. Majewska
- Faculty
of Chemistry, University of Warsaw, ul. Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Shona Ramsay
- Department
of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, Aberdeen AB24 3UE, U.K.
| | - Cheng Wang
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Chenhui Zhu
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Rebecca Walker
- Department
of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, Aberdeen AB24 3UE, U.K.
| | - John M. D. Storey
- Department
of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, Aberdeen AB24 3UE, U.K.
| | - Corrie T. Imrie
- Department
of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, Aberdeen AB24 3UE, U.K.
| | - Ewa Gorecka
- Faculty
of Chemistry, University of Warsaw, ul. Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Damian Pociecha
- Faculty
of Chemistry, University of Warsaw, ul. Zwirki i Wigury 101, 02-089 Warsaw, Poland
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18
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Szydlowska J, Majewski P, Čepič M, Vaupotič N, Rybak P, Imrie CT, Walker R, Cruickshank E, Storey JMD, Damian P, Gorecka E. Ferroelectric Nematic-Isotropic Liquid Critical End Point. PHYSICAL REVIEW LETTERS 2023; 130:216802. [PMID: 37295101 DOI: 10.1103/physrevlett.130.216802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 04/18/2023] [Indexed: 06/12/2023]
Abstract
A critical end point above which an isotropic phase continuously evolves into a polar (ferroelectric) nematic phase with an increasing electric field is found in a ferroelectric nematic liquid crystalline material. The critical end point is approximately 30 K above the zero-field transition temperature from the isotropic to nematic phase and at an electric field of the order of 10 V/μm. Such systems are interesting from the application point of view because a strong birefringence can be induced in a broad temperature range in an optically isotropic phase.
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Affiliation(s)
- Jadwiga Szydlowska
- Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Pawel Majewski
- Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Mojca Čepič
- Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Department of Physics and Technical Studies, Faculty of Education, University of Ljubljana, Kardeljeva ploščad 16, 1000 Ljubljana, Slovenia
| | - Nataša Vaupotič
- Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia
| | - Paulina Rybak
- Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Corrie T Imrie
- Department of Chemistry, University of Aberdeen, Old Aberdeen AB24 3UE, United Kingdom
| | - Rebecca Walker
- Department of Chemistry, University of Aberdeen, Old Aberdeen AB24 3UE, United Kingdom
| | - Ewan Cruickshank
- Department of Chemistry, University of Aberdeen, Old Aberdeen AB24 3UE, United Kingdom
| | - John M D Storey
- Department of Chemistry, University of Aberdeen, Old Aberdeen AB24 3UE, United Kingdom
| | - Pociecha Damian
- Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Ewa Gorecka
- Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
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19
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Sebastián N, Lovšin M, Berteloot B, Osterman N, Petelin A, Mandle RJ, Aya S, Huang M, Drevenšek-Olenik I, Neyts K, Mertelj A. Polarization patterning in ferroelectric nematic liquids via flexoelectric coupling. Nat Commun 2023; 14:3029. [PMID: 37230977 DOI: 10.1038/s41467-023-38749-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 05/11/2023] [Indexed: 05/27/2023] Open
Abstract
The recently discovered ferroelectric nematic liquids incorporate to the functional combination of fluidity, processability and anisotropic optical properties of nematic liquids, an astonishing range of physical properties derived from the phase polarity. Among them, the remarkably large values of second order optical susceptibility encourage to exploit these new materials for non-linear photonic applications. Here we show that photopatterning of the alignment layer can be used to structure polarization patterns. To do so, we take advantage of the flexoelectric effect and design splay structures that geometrically define the polarization direction. We demonstrate the creation of periodic polarization structures and the possibility of guiding polarization by embedding splay structures in uniform backgrounds. The demonstrated capabilities of polarization patterning, open a promising new route for the design of ferroelectric nematic based photonic structures and their exploitation.
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Affiliation(s)
| | - Matija Lovšin
- Jožef Stefan Institute, Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
| | - Brecht Berteloot
- Liquid Crystals and Photonics Group, ELIS Department, Ghent University, Ghent, Belgium
| | - Natan Osterman
- Jožef Stefan Institute, Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
| | - Andrej Petelin
- Jožef Stefan Institute, Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
| | - Richard J Mandle
- School of Physics and Astronomy, University of Leeds, Leeds, UK
- School of Chemistry, University of Leeds, Leeds, UK
| | - Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou, China
| | - Mingjun Huang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou, China
| | - Irena Drevenšek-Olenik
- Jožef Stefan Institute, Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
| | - Kristiaan Neyts
- Liquid Crystals and Photonics Group, ELIS Department, Ghent University, Ghent, Belgium
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20
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Tufaha N, Cruickshank E, Pociecha D, Gorecka E, Storey JM, Imrie CT. Molecular Shape, Electronic Factors, and the Ferroelectric Nematic Phase: Investigating the Impact of Structural Modifications. Chemistry 2023; 29:e202300073. [PMID: 36807424 PMCID: PMC10962687 DOI: 10.1002/chem.202300073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023]
Abstract
The synthesis and characterisation of two series of low molar mass mesogens, the (4-nitrophenyl) 2-alkoxy-4-(4-methoxybenzoyl)oxybenzoates (NT3.m) and the (3-fluoro-4-nitrophenyl) 2-alkoxy-4-(4-methoxybenzoyl)oxybenzoates (NT3F.m), are reported in order to investigate the effect of changing the position of a lateral alkoxy chain from the methoxy-substituted terminal ring to the central phenyl ring in these two series of materials based on RM734. All members of the NT3.m series exhibited a conventional nematic phase, N, which preceded the ferroelectric nematic phase, NF , whereas all the members of the NT3F.m series exhibited direct NF -I transitions except for NT3F.1 which also exhibited an N phase. These materials cannot be described as wedge-shaped, yet their values of the ferroelectric nematic-nematic transition temperature, TN F N ${{_{{\rm N}{_{{\rm F}}}{\rm N}}}}$ , exceed those of the corresponding materials with the lateral alkoxy chain located on the methoxy-substituted terminal ring. In part, this may be attributed to the effect that changing the position of the lateral alkoxy chain has on the electronic properties of these materials, specifically on the electron density associated with the methoxy-substituted terminal aromatic ring. The value of TNI decreased with the addition of a fluorine atom ortho to the nitro group in NT3F.1, however, the opposite behaviour was found when the transition temperatures of the NF phase were compared which are higher for the NT3F.m series. This may reflect a change in the polarity and polarizability of the NT3F.m series compared to the NT3.m series. Therefore, it is suggested that, rather than simply promoting a tapered shape, the role of the lateral chain in inhibiting anti-parallel associations and its effect on the electronic properties of the molecules are the key factors in driving the formation of the NF phase.
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Affiliation(s)
- Naila Tufaha
- Department of ChemistryUniversity of AberdeenOld AberdeenAB24 3UEUK
| | - Ewan Cruickshank
- Department of ChemistryUniversity of AberdeenOld AberdeenAB24 3UEUK
| | - Damian Pociecha
- Faculty of ChemistryUniversity of Warsawul. Zwirki i Wigury 10102-089WarsawPoland
| | - Ewa Gorecka
- Faculty of ChemistryUniversity of Warsawul. Zwirki i Wigury 10102-089WarsawPoland
| | - John M.D. Storey
- Department of ChemistryUniversity of AberdeenOld AberdeenAB24 3UEUK
| | - Corrie T. Imrie
- Department of ChemistryUniversity of AberdeenOld AberdeenAB24 3UEUK
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21
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Mrukiewicz M, Perkowski P, Karcz J, Kula P. Ferroelectricity in a nematic liquid crystal under a direct current electric field. Phys Chem Chem Phys 2023; 25:13061-13071. [PMID: 37114748 DOI: 10.1039/d3cp00714f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
We investigated the electrical properties of the liquid crystal compound 4-(4-nitrophenoxycarbonyl)phenyl 2,4-dimethoxybenzoate, known as RM734, exhibiting a ferroelectric nematic phase. The influence of alternating (AC) and direct (DC) current electric fields on the switching process of the polarization vector and dielectric constant of planarly aligned ferronematic and nematic phases were examined. The decrease of the real part of electric permittivity in the ferronematic phase and the creation of a ferroelectric order in the nematic phase under a DC field were demonstrated. The analysis of the results reveals the latching of the ferroelectric state. The applied DC field created a ferroelectric mode in the nematic phase. A new model of collective and molecular relaxations considering the domain structure of the ferronematic phase was proposed. The temperature and DC field dependence of dielectric properties was shown. Spontaneous polarization was measured using the field reversal technique. The spontaneous polarization value reaches the maximum at a fixed temperature.
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Affiliation(s)
- Mateusz Mrukiewicz
- Institute of Applied Physics, Military University of Technology, 2 Kaliskiego, 00-908 Warsaw, Poland.
| | - Paweł Perkowski
- Institute of Applied Physics, Military University of Technology, 2 Kaliskiego, 00-908 Warsaw, Poland.
| | - Jakub Karcz
- Institute of Chemistry, Military University of Technology, 2 Kaliskiego, 00-908 Warsaw, Poland
| | - Przemysław Kula
- Institute of Chemistry, Military University of Technology, 2 Kaliskiego, 00-908 Warsaw, Poland
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22
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Máthé MT, Farkas B, Péter L, Buka Á, Jákli A, Salamon P. Electric field-induced interfacial instability in a ferroelectric nematic liquid crystal. Sci Rep 2023; 13:6981. [PMID: 37117269 PMCID: PMC10147939 DOI: 10.1038/s41598-023-34067-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 04/24/2023] [Indexed: 04/30/2023] Open
Abstract
Studies of sessile droplets and fluid bridges of a ferroelectric nematic liquid crystal in externally applied electric fields are presented. It is found that above a threshold, the interface of the fluid with air undergoes a fingering instability or ramification, resembling to Rayleigh-type instability observed in charged droplets in electric fields or circular drop-type instabilities observed in ferromagnetic liquids in magnetic field. The frequency dependence of the threshold voltage was determined in various geometries. The nematic director and ferroelectric polarization direction was found to point along the tip of the fingers that appear to repel each other, indicating that the ferroelectric polarization is essentially parallel to the director. The results are interpreted in connection to the Rayleigh and circular drop-type instabilities.
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Affiliation(s)
- Marcell Tibor Máthé
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
- Eötvös Loránd University, P.O. Box 32, 1518, Budapest, Hungary
| | - Bendegúz Farkas
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
- Eötvös Loránd University, P.O. Box 32, 1518, Budapest, Hungary
| | - László Péter
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
| | - Ágnes Buka
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
| | - Antal Jákli
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary.
- Materials Sciences Graduate Program and Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.
- Department of Physics, Kent State University, Kent, OH, 44242, USA.
| | - Péter Salamon
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary.
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23
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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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24
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Yadav N, Panarin YP, Vij JK, Jiang W, Mehl GH. Two mechanisms for the formation of ferronematic phase in DIO as studied by dielectric spectroscopy. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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25
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Perera K, Saha R, Nepal P, Dharmarathna R, Hossain MS, Mostafa M, Adaka A, Waroquet R, Twieg RJ, Jákli A. Ferroelectric nematic droplets in their isotropic melt. SOFT MATTER 2023; 19:347-354. [PMID: 36597812 DOI: 10.1039/d2sm01395a] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The isotropic to ferroelectric nematic liquid transition was theoretically studied over one hundred years ago, but its experimental studies are rare. Here we present experimental results and theoretical considerations of novel electromechanical effects of ferroelectric nematic liquid crystal droplets coexisting with the isotropic melt. We find that the droplets have flat pancake-like shapes that are thinner than the sample thickness as long as there is room to increase the lateral droplet size. In the center of the droplets a wing-shaped defect with low birefringence is present that moves perpendicular to a weak in-plane electric field, and then extends and splits in two at higher fields. Parallel to the defect motion and extension, the entire droplet drifts along the electric field with a speed that is independent of the size of the droplet and is proportional to the amplitude of the electric field. After the field is increased above 1 mV μm-1 the entire droplet gets deformed and oscillates with the field. These observations led us to determine the polarization field and revealed the presence of a pair of positive and negative bound electric charges due to divergences of polarization around the defect volume.
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Affiliation(s)
- Kelum Perera
- Department of Physics, Kent State University, Kent OH, 44242, USA.
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
| | - Rony Saha
- Department of Physics, Kent State University, Kent OH, 44242, USA.
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
| | - Pawan Nepal
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Rohan Dharmarathna
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
| | - Md Sakhawat Hossain
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
- Materials Science Graduate Program, Kent State University, Kent OH, 44242, USA
| | - Md Mostafa
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
- Materials Science Graduate Program, Kent State University, Kent OH, 44242, USA
| | - Alex Adaka
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
- Materials Science Graduate Program, Kent State University, Kent OH, 44242, USA
| | - Ronan Waroquet
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
| | - Robert J Twieg
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Antal Jákli
- Department of Physics, Kent State University, Kent OH, 44242, USA.
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent OH, 44242, USA
- Materials Science Graduate Program, Kent State University, Kent OH, 44242, USA
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26
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Thoen J, Cordoyiannis G, Jiang W, Mehl GH, Glorieux C. Phase transitions study of the liquid crystal DIO with a ferroelectric nematic, a nematic, and an intermediate phase and of mixtures with the ferroelectric nematic compound RM734 by adiabatic scanning calorimetry. Phys Rev E 2023; 107:014701. [PMID: 36797863 DOI: 10.1103/physreve.107.014701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/21/2022] [Indexed: 06/18/2023]
Abstract
High-resolution calorimetry has played a significant role in providing detailed information on phase transitions in liquid crystals. In particular, adiabatic scanning calorimetry (ASC), capable of providing simultaneous information on the temperature dependence of the specific enthalpy h(T) and on the specific heat capacity c_{p}(T), has proven to be an important tool to determine the order of transitions and render high-resolution information on pretransitional thermal behavior. Here we report on ASC results on the compound 2,3',4',5'-tetrafluoro[1,1'-biphenyl]-4-yl 2,6-difluoro-4-(5-propyl-1,3-dioxan-2-yl) benzoate (DIO) and on mixtures with 4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (RM734). Both compounds exhibit a low-temperature ferroelectric nematic phase (N_{F}) and a high-temperature paraelectric nematic phase (N). However, in DIO these two phases are separated by an intermediate phase (N_{x}). From the detailed data of h(T) and c_{p}(T), we found that the intermediate phase was present in all the mixtures over the complete composition range, albeit with strongly decreasing temperature width for that phase with decreasing mole fraction of DIO (x_{DIO}). The x_{DIO} dependence on the transition temperatures for both transitions could be well described by a quadratic function. Both these transitions were weakly first order. The true latent heat of the N_{x}-N transition of DIO was as low as L=0.0075±0.0005J/g and L=0.23±0.03J/g for the N_{F}-N_{x} transition, which is about twice the previously reported value of 0.115 J/g for the N_{F}-N transition in RM734. In the mixtures both transition latent heats decrease gradually with decreasing x_{DIO}. At all the N_{x}-N transitions pretransition fluctuation effects are absent and these transitions are purely but very weakly first order. As in RM734 the transition from the N_{F} to the higher-temperature phase exhibits substantial pretransitional behavior, in particular, in the high-temperature phase. Power-law analysis of c_{p}(T) resulted in an effective critical exponent α=0.88±0.1 for DIO and this value decreased in the mixtures with decreasing x_{DIO} toward α=0.50±0.05 reported for RM734. Ideal mixture analysis of the phase diagram was consistent with ideal mixture behavior provided the total transition enthalpy change was used in the analysis.
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Affiliation(s)
- J Thoen
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
| | - G Cordoyiannis
- Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia
| | - W Jiang
- Department of Chemistry, University of Hull, Hull HU6 7RX, United Kingdom
| | - G H Mehl
- Department of Chemistry, University of Hull, Hull HU6 7RX, United Kingdom
| | - C Glorieux
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
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27
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Polar Nematic Phase in Short-Chained Fluorinated Hydrogen-Bonded Liquid Crystals. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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28
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Derbali M, Soltani T, Guesmi A, Ben Hamadi N, Jeanneau E, Chevalier Y. Synthesis, thermal, dielectric and electro-optic properties of new series of fluorinated hydrogen-bonded liquid crystals. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120510] [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]
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29
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Zavvou E, Klasen-Memmer M, Manabe A, Bremer M, Eremin A. Polarisation-driven magneto-optical and nonlinear-optical behaviour of a room-temperature ferroelectric nematic phase. SOFT MATTER 2022; 18:8804-8812. [PMID: 36354279 DOI: 10.1039/d2sm01298g] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Nematics with a broken polar symmetry are one of the fascinating recent discoveries in the field of soft matter. High spontaneous polarisation and the fluidity of the ferroelectric nematic NF phase make such materials attractive for future applications and interesting for fundamental research. Here, we explore the polar and mechanical properties of a room-temperature ferroelectric nematic and its behaviour in a magnetic field. We show that NF is much less susceptible to the splay deformation than to the twist. The strong splay rigidity can be attributed to the electrostatic self-interaction of polarisation avoiding the polarisation splay.
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Affiliation(s)
- Evangelia Zavvou
- Otto von Guericke University Magdeburg, Institute of Physics, Dept. Nonlinear Phenomena, Magdeburg, Germany.
- Department of Physics, University of Patras, 26504, Patras, Greece
| | | | | | | | - Alexey Eremin
- Otto von Guericke University Magdeburg, Institute of Physics, Dept. Nonlinear Phenomena, Magdeburg, Germany.
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30
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Eremin A, Murad A, Alaasar M. Shear-induced birefringence in an optically isotropic cubic liquid crystalline phase. SOFT MATTER 2022; 18:8315-8319. [PMID: 36300301 DOI: 10.1039/d2sm01148d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We report an unusually strong flow-induced birefringence in an optically isotropic cubic phase occurring below the isotropic chiral conglomerate phase formed by a low-molecular-weight polycatenar mesogen. The transition into the birefringent state occurs thresholdless and the induced birefringence is comparable with that observed in polymeric systems. We suggest that the flow-induced deformation of the cubic structure is responsible for the strong rheo-optical response.
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Affiliation(s)
- Alexey Eremin
- Department of Nonlinear Phenomena, Institute for Physics Otto von Guericke University Magdeburg, Magdeburg, Germany.
| | - Ahmad Murad
- Department of Nonlinear Phenomena, Institute for Physics Otto von Guericke University Magdeburg, Magdeburg, Germany.
| | - Mohamed Alaasar
- Department of Chemistry, Martin-Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.
- Department of Chemistry, Cairo University, Giza, Egypt.
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31
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Song Y, Deng M, Wang Z, Li J, Lei H, Wan Z, Xia R, Aya S, Huang M. Emerging Ferroelectric Uniaxial Lamellar (Smectic A F) Fluids for Bistable In-Plane Polarization Memory. J Phys Chem Lett 2022; 13:9983-9990. [PMID: 36263973 DOI: 10.1021/acs.jpclett.2c02846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The emerging matter category of liquid-matter ferroelectrics, i.e., ferroelectric nematics, demonstrates an unprecedented combination of fluidity and spontaneous polarization. However, unlike traditional ferroelectrics, the field-switched polarization at zero-field cannot be conserved, so the memory effect remains challenging. Here we report another new type of ferroelectric liquid crystal state, dubbed the ferroelectric smectic A phase, where the polarization is longitudinally coupled to the smectic quasi-layer order. With higher packing density, the phase exhibits higher values of refractive anisotropy and spontaneous polarization compared to the ferroelectric nematics. A delicate balance between the liquid crystal elasticity and flow viscosity enables both the switching and memory of the polarization field, thus opening the door toward realizing liquid-matter ferroelectric memory devices.
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Affiliation(s)
- Yaohao Song
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Minghui Deng
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Zhidong Wang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Jinxing Li
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Huanyu Lei
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Zhe Wan
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Runli Xia
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Mingjun Huang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
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32
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Cruickshank E, Walker R, Storey JMD, Imrie CT. The effect of a lateral alkyloxy chain on the ferroelectric nematic phase. RSC Adv 2022; 12:29482-29490. [PMID: 36320775 PMCID: PMC9562421 DOI: 10.1039/d2ra05628c] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 10/06/2022] [Indexed: 11/05/2022] Open
Abstract
The synthesis and characterisation of two series of low molar mass liquid crystals, the 4-[(4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 5-m) and the 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 6-m) are reported in order to explore the effects of a lateral alkyloxy chain on the formation and stability of the recently discovered ferroelectric nematic phase. In both series m, the number of carbon atoms in the lateral chain, is varied from one to nine. The two series differ by the addition of a fluorine substituent in the 6-m series. 5-1 is the extensively studied ferroelectric nematogen RM734. All the members of the 5-m series exhibited both a conventional nematic, N, and ferroelectric nematic, NF, phase, whereas all the members of the 6-m series exhibit a direct NF-I transition with the exception of 6-1 that also exhibits a N phase. The replacement of a hydrogen atom by a fluorine atom reduces the nematic-isotropic transition temperature, T NI, whereas the ferroelectric nematic-nematic, or isotropic, transition temperature, T NFN/I, increases. This is interpreted in terms of the reduced structural anisotropy associated with the larger fluorine atom whereas the increase in the stability of the NF phase reflects changes in polarity and polarizability. The dependence of T NI and T NFN/I on m in both series is similar, and these initially decrease on increasing m but converge to limiting values on further increasing m. This suggests that the lateral alkyloxy chain may adopt conformations in which it lies along the major axis of the mesogenic unit.
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Affiliation(s)
- Ewan Cruickshank
- Department of Chemistry, University of AberdeenOld AberdeenAB24 3UEUK
| | - Rebecca Walker
- Department of Chemistry, University of AberdeenOld AberdeenAB24 3UEUK
| | - John M. D. Storey
- Department of Chemistry, University of AberdeenOld AberdeenAB24 3UEUK
| | - Corrie T. Imrie
- Department of Chemistry, University of AberdeenOld AberdeenAB24 3UEUK
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33
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Pociecha D, Walker R, Cruickshank E, Szydlowska J, Rybak P, Makal A, Matraszek J, Wolska JM, Storey JM, Imrie CT, Gorecka E. Intrinsically chiral ferronematic liquid crystals: An inversion of the helical twist sense at the chiral nematic – Chiral ferronematic phase transition. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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34
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Kikuchi H, Matsukizono H, Iwamatsu K, Endo S, Anan S, Okumura Y. Fluid Layered Ferroelectrics with Global C ∞v Symmetry. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2202048. [PMID: 35869031 PMCID: PMC9475520 DOI: 10.1002/advs.202202048] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/01/2022] [Indexed: 06/15/2023]
Abstract
Ferroelectricity in fluid materials, which allows free rotation of molecules, is an unusual phenomenon raising cutting-edge questions in science. Conventional ferroelectric liquid crystals have been found in phases with low symmetry that permit the presence of spontaneous polarization. Recently, the discovery of ferroelectricity with high symmetry in the nematic phase has attracted considerable attention. However, the physical mechanism and molecular origin of ferroelectricity are poorly understood and a large domain of macroscopically oriented spontaneous polarization is difficult to fabricate in the ferroelectric nematic phase. This study reports new fluid layered ferroelectrics with the C∞v symmetry in which nearly complete orientation of the spontaneous polarization remains stable under zero electric field without any orientation treatment. These ferroelectrics are obtained by simplifying the molecular structure of a compound with a known ferroelectric nematic phase, although the simplification reduced the dipole moment. The results provide useful insights into the mechanism of ferroelectricity due to dipole-dipole interactions in molecular assemblies. The new ferroelectric materials are promising for a wide range of applications as soft ferroelectrics.
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Affiliation(s)
- Hirotsugu Kikuchi
- Kyushu UniversityInstitute for Materials Chemistry and Engineering6‐1 Kasuga‐KoenKasugaFukuoka816‐8580Japan
| | - Hiroyuki Matsukizono
- Kyushu UniversityInstitute for Materials Chemistry and Engineering6‐1 Kasuga‐KoenKasugaFukuoka816‐8580Japan
| | - Koki Iwamatsu
- Kyushu UniversityInterdisciplinary Graduate School of Engineering Sciences6‐1 Kasuga‐KoenKasugaFukuoka816‐8580Japan
| | - Sota Endo
- Kyushu UniversityInterdisciplinary Graduate School of Engineering Sciences6‐1 Kasuga‐KoenKasugaFukuoka816‐8580Japan
| | - Shizuka Anan
- Kyushu UniversityInstitute for Materials Chemistry and Engineering6‐1 Kasuga‐KoenKasugaFukuoka816‐8580Japan
| | - Yasushi Okumura
- Kyushu UniversityInstitute for Materials Chemistry and Engineering6‐1 Kasuga‐KoenKasugaFukuoka816‐8580Japan
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35
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Sebastián N, Čopič M, Mertelj A. Ferroelectric nematic liquid-crystalline phases. Phys Rev E 2022; 106:021001. [PMID: 36109969 DOI: 10.1103/physreve.106.021001] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Recent experimental realization of ferroelectric nematic liquid crystalline phases stimulated material development and numerous experimental studies of these phases, guided by their fundamental and applicative interest. In this Perspective, we give an overview of this emerging field by linking history and theoretical predictions to a general outlook of the development and properties of the materials exhibiting ferroelectric nematic phases. We will highlight the most relevant observations to date, e.g., giant dielectric permittivity values, polarization values an order of magnitude larger than in classical ferroelectric liquid crystals, and nonlinear optical coefficients comparable with several ferroelectric solid materials. Key observations of anchoring and electro-optic behavior will also be examined. The collected contributions lead to a final discussion on open challenges in materials development, theoretical description, experimental explorations, and possible applications of the ferroelectric phases.
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Affiliation(s)
| | - Martin Čopič
- J. Stefan Institute, SI-1000 Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
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36
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Mandle RJ. A new order of liquids: polar order in nematic liquid crystals. SOFT MATTER 2022; 18:5014-5020. [PMID: 35776092 DOI: 10.1039/d2sm00543c] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Given the widespread adoption of display technology based on nematic liquid crystals, the discovery of new nematic phases at thermodynamic equilibrium, although extremely rare, generates much excitement. The remarkable discovery polar order and giant ferroelectric polarisation in a nematic fluid is a watershed moment in soft matter research, and is one of the most important discoveries in the 150 year history of liquid crystals. After a brief introduction to this emerging field, we present the current state-of-the art in terms of understanding the molecular origins of this phase, before exploring how molecular structure underpins the incidence of this phase, as well as exploring future directions.
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Affiliation(s)
- Richard J Mandle
- School of Physics and Astronomy, University of Leeds, UK, LS2 9JT
- School of Chemistry, University of Leeds, UK, LS2 9HT.
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37
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Basnet B, Rajabi M, Wang H, Kumari P, Thapa K, Paul S, Lavrentovich MO, Lavrentovich OD. Soliton walls paired by polar surface interactions in a ferroelectric nematic liquid crystal. Nat Commun 2022; 13:3932. [PMID: 35798735 PMCID: PMC9262936 DOI: 10.1038/s41467-022-31593-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 06/24/2022] [Indexed: 11/09/2022] Open
Abstract
Surface interactions are responsible for many properties of condensed matter, ranging from crystal faceting to the kinetics of phase transitions. Usually, these interactions are polar along the normal to the interface and apolar within the interface. Here we demonstrate that polar in-plane surface interactions of a ferroelectric nematic NF produce polar monodomains in micron-thin planar cells and stripes of an alternating electric polarization, separated by \documentclass[12pt]{minimal}
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\begin{document}$${180}^{{{{{{\rm{o}}}}}}}$$\end{document}180o domain walls, in thicker slabs. The surface polarity binds together pairs of these walls, yielding a total polarization rotation by \documentclass[12pt]{minimal}
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\begin{document}$${360}^{{{{{{\rm{o}}}}}}}$$\end{document}360o. The polar contribution to the total surface anchoring strength is on the order of 10%. The domain walls involve splay, bend, and twist of the polarization. The structure suggests that the splay elastic constant is larger than the bend modulus. The \documentclass[12pt]{minimal}
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\begin{document}$${360}^{{{{{{\rm{o}}}}}}}$$\end{document}360o pairs resemble domain walls in cosmology models with biased vacuums and ferromagnets in an external magnetic field. Surface interactions are usually polar along the normal to the interface and apolar within the interface. Here, the authors find that polar in-plane surface interactions produce domain structures in the bulk of a ferroelectric nematic liquid crystal.
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Affiliation(s)
- Bijaya Basnet
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.,Materials Science Graduate Program, Kent State University, Kent, OH, 44242, USA
| | - Mojtaba Rajabi
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.,Department of Physics, Kent State University, Kent, OH, 44242, USA
| | - Hao Wang
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
| | - Priyanka Kumari
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.,Materials Science Graduate Program, Kent State University, Kent, OH, 44242, USA
| | - Kamal Thapa
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.,Department of Physics, Kent State University, Kent, OH, 44242, USA
| | - Sanjoy Paul
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
| | - Maxim O Lavrentovich
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA
| | - Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA. .,Materials Science Graduate Program, Kent State University, Kent, OH, 44242, USA. .,Department of Physics, Kent State University, Kent, OH, 44242, USA.
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38
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Wide Nematogenic Azomethine/Ester Liquid Crystals Based on New Biphenyl Derivatives: Mesomorphic and Computational Studies. Molecules 2022; 27:molecules27134150. [PMID: 35807398 PMCID: PMC9268434 DOI: 10.3390/molecules27134150] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/18/2022] [Accepted: 06/25/2022] [Indexed: 02/04/2023] Open
Abstract
The thermal stability and mesomorphic behavior of a new biphenyl azomethine liquid crystal homologues series, (E)-4-(([1,1′-biphenyl]-4-ylmethylene)amino)phenyl 4-(alkoxy)benzoate, In, were investigated. The chemical structures of the synthesized compounds were characterized using FT-IR, NMR, and elemental analyses. Differential scanning calorimetry (DSC) and polarized optical microscopy were employed to evaluate the mesomorphic characteristics of the designed homologues. The examined homologues possessed high thermal stability and broad nematogenic temperature ranges. Furthermore, the homologues were covered by enantiotropic nematic phases. The experimental measurements of the mesomorphic behavior were substantiated by computational studies using the density functional theory (DFT) approach. The reactivity parameters, dipole moments, and polarizability of the studied molecules are discussed. The theoretical calculations demonstrated that as the chain length increased, the polarizability of the studied series increased; while it did not significantly affect the HOMO–LUMO energy gap and other reactivity descriptors, the biphenyl moiety had an essential impact on the stability of the possible geometries and their thermal as well as physical parameters.
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39
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Conception, Discovery, Invention, Serendipity and Consortia: Cyanobiphenyls and Beyond. CRYSTALS 2022. [DOI: 10.3390/cryst12060825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
In the 1960s, a world-wide change in electronic devices was about to occur with the invention of integrated circuits. The chip was upon us, which instantly created the need for a revolution in visual communication displays. From the watch to the computer monitor, to TVs, to the phone, nearly all everyday applications were affected. A strange connection in technology underpinned these changes; the linkage between silicon semiconductors and organic compounds that did not know if they were solids or liquids. Liquid crystals had been known since 1888 and had seen little usage until they were inserted between conducting glass slides and an applied electric field. Suddenly, the possibility of driving images with low voltage fields became obvious. Many major companies took up the challenge of commercialisation, but in the UK a curious combination of government research facilities, electronic companies and one small university came together in 1970 to form a consortium and within two years the basis for new technologies had been founded. Chemistry is part of this story, with new conceptions, discoveries and inventions, and the luck to be in the right place at the right time.
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40
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Song Y, Li J, Xia R, Xu H, Zhang X, Lei H, Peng W, Dai S, Aya S, Huang M. Development of emergent ferroelectric nematic liquid crystals with highly fluorinated and rigid mesogens. Phys Chem Chem Phys 2022; 24:11536-11543. [PMID: 35506891 DOI: 10.1039/d2cp01110g] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The emerging ferroelectric nematic liquid crystals have been attracting broader interests in new liquid crystal physics and their unique material properties. One big challenge for the ferroelectric nematic research is to enrich the material choice, which is now limited to RM734 and DIO families as representatives, in sharp contrast to the enormously diverse variety of the traditional apolar nematic liquid crystals. Here, we report a design of novel ferroelectric nematic materials with highly fluorinated and rigid mesogens. Noteworthily, they show distinct chemical structural features compared with previous aromatic ester-based molecules. The ferroelectric nematic phase was identified and confirmed through rigorous experiments. The bulk polarization was found to become purely along the long axis director, creating giant dielectric anisotropy. This work demonstrates a great potential for expanding ferroelectric nematic material diversity and will accelerate the corresponding application research and technology innovation.
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Affiliation(s)
- Yaohao Song
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Jinxing Li
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Runli Xia
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Hao Xu
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Xinxin Zhang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Huanyu Lei
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Weifeng Peng
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Shuqi Dai
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China. .,Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Mingjun Huang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China. .,Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
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41
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Máthé MT, Buka Á, Jákli A, Salamon P. Ferroelectric nematic liquid crystal thermomotor. Phys Rev E 2022; 105:L052701. [PMID: 35706177 DOI: 10.1103/physreve.105.l052701] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 04/14/2022] [Indexed: 05/15/2023]
Abstract
A thermal gradient-induced circular motion of particles placed on ferroelectric nematic liquid crystal sessile drops is demonstrated and explained. Unlike hurricanes and tornadoes that are the prime examples for thermal motors and where turbulent flows are apparent, here the texture without tracer particles appears completely steady indicating laminar flow. We provide a simple model showing that the tangential arrangement of the ferroelectric polarization combined with the vertical thermal gradient and the pyroelectricity of the fluid drives the rotation of the tracer particles that become electrically charged in the fluid. These observations provide a fascinating example of the unique nature of fluid ferroelectric liquid crystals.
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Affiliation(s)
- Marcell Tibor Máthé
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest H-1525, Hungary
- Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Ágnes Buka
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest H-1525, Hungary
| | - Antal Jákli
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest H-1525, Hungary
- Materials Sciences Graduate Program and Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA
- Department of Physics, Kent State University, Kent, Ohio 44242, USA
| | - Péter Salamon
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest H-1525, Hungary
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42
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Nishikawa H, Sano K, Araoka F. Anisotropic fluid with phototunable dielectric permittivity. Nat Commun 2022; 13:1142. [PMID: 35241651 PMCID: PMC8894468 DOI: 10.1038/s41467-022-28763-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/11/2022] [Indexed: 11/24/2022] Open
Abstract
Dielectric permittivity, a measure of polarisability, is a fundamental parameter that dominates various physical phenomena and properties of materials. However, it remains a challenge to control the dielectric permittivity of materials reversibly over a large range. Herein, we report an anisotropic fluid with photoresponsive dielectric permittivity (200 < ε < 18,000) consisting of a fluorinated liquid-crystalline molecule (96 wt%) and an azobenzene-tethered phototrigger (4 wt%). The reversible trans-cis isomerisation of the phototrigger under blue and green light irradiation causes a switch between two liquid-crystalline phases that exhibit different dielectric permittivities, with a rapid response time (<30 s) and excellent reversibility (~100 cycles). This anisotropic fluid can be used as a flexible photovariable capacitor that, for example, allows the reversible modulation of the sound frequency over a wide range (100 < f < 8500 Hz) in a remote manner using blue and green wavelengths. Light stimuli are widely used to control material properties, yet it remains challenging to reversibly photocontrol the dielectric permittivity. Nishikawa et al. achieve this goal in an anisotropic fluid via its liquid crystal phase transition induced by isomerization of an azobenzene-tethered phototrigger.
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Affiliation(s)
- Hiroya Nishikawa
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
| | - Koki Sano
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan. .,JST PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan. .,Department of Chemistry and Materials, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567, Japan.
| | - Fumito Araoka
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
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43
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Zheng X, Zhan Y, Liu Y, Lu M, Jiao E, Zhang H, Shi J, Lu M, Wu K. High intrinsic thermally conductivity side-chain liquid crystalline polysiloxane films grafted with pendent difunctional mesogenic groups. Polym Chem 2022. [DOI: 10.1039/d2py00432a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Herein, the microscopic ordered aggregation morphologies of SCLCP films are investigated, and molecular structures with regular arrangement can increase heat transfer via suppressing the scattering of phonons, thus greatly improving the λ of SCLCPs.
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Affiliation(s)
- Xiaole Zheng
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- Guangdong Provincial Key Laboratory of Organic Polymer Materials for Electronics, Guangzhou 510650, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yingjie Zhan
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- CAS Engineering Laboratory for Special Fine Chemicals, Guangzhou 510650, People's Republic of China
| | - Yingchun Liu
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- CAS Engineering Laboratory for Special Fine Chemicals, Guangzhou 510650, People's Republic of China
| | - Maoping Lu
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- Guangdong Provincial Key Laboratory of Organic Polymer Materials for Electronics, Guangzhou 510650, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Enxiang Jiao
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- New Materials Research Institute of CASCHEM (Chongqing) Co., Ltd, Chongqing, 400714, PR China
| | - Hangzhen Zhang
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- CASH GCC Shaoguan Research Institute of Advanced Materials Co., Ltd, Shaoguan 512400, People's Republic of China
| | - Jun Shi
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- New Materials Research Institute of CASCHEM (Chongqing) Co., Ltd, Chongqing, 400714, PR China
- CASH GCC Shaoguan Research Institute of Advanced Materials Co., Ltd, Shaoguan 512400, People's Republic of China
| | - Mangeng Lu
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- CAS Engineering Laboratory for Special Fine Chemicals, Guangzhou 510650, People's Republic of China
- New Materials Research Institute of CASCHEM (Chongqing) Co., Ltd, Chongqing, 400714, PR China
| | - Kun Wu
- Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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44
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Rudquist P. Revealing the polar nature of a ferroelectric nematic by means of circular alignment. Sci Rep 2021; 11:24411. [PMID: 34949781 PMCID: PMC8702550 DOI: 10.1038/s41598-021-04028-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/14/2021] [Indexed: 11/09/2022] Open
Abstract
The recent discovery of spontaneously polar nematic liquid crystals-so-called ferroelectric nematics-more than a century after the first discussions about their possible existence-has attracted large interest, both from fundamental scientific and applicational points of view. However, the experimental demonstration of such a phase has, so-far, been non-trivial. Here I present a direct method for the experimental verification of a ferroelectric nematic liquid crystal phase. The method utilizes a single sample cell where the two substrates are linearly and circularly rubbed, respectively, and the ferroelectric nematic phase (NF) is revealed by the orientation of the resulting disclination lines in the cell.
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Affiliation(s)
- Per Rudquist
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296, Gothenburg, Sweden.
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Li J, Xia R, Xu H, Yang J, Zhang X, Kougo J, Lei H, Dai S, Huang H, Zhang G, Cen F, Jiang Y, Aya S, Huang M. How Far Can We Push the Rigid Oligomers/Polymers toward Ferroelectric Nematic Liquid Crystals? J Am Chem Soc 2021; 143:17857-17861. [PMID: 34657433 DOI: 10.1021/jacs.1c09594] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The emerging ferroelectric nematic (NF) liquid crystal is a novel 3D-ordered liquid exhibiting macroscopic electric polarization. The combination of the ultrahigh dielectric constant, strong nonlinear optical signal, and high sensitivity to the electric field makes NF materials promising for the development of advanced liquid crystal electroopic devices. Previously, all studies focused on the rod-shaped small molecules with limited length (l) range and dipole moment (μ) values. Here, through the precision synthesis, we extend the aromatic rod-shaped mesogen to oligomer/polymer (repeat unit up to 12 with monodisperse molecular-weight dispersion) and increase the μ value over 30 Debye (D). The NF phase has a widespread existence far beyond our expectation and could be observed in all the oligomer/polymer length range. Notably, the NF phase experiences a nontrivial evolution pathway with the traditional apolar nematic phase completely suppressed, i.e., the NF phase nucleates directly from the isotropic liquid phase. The discovery of thte ferroelectric packing of oligomer/polymer rods not only offers the concept of extending the NF state to oligomers/polymers but also provides some previously overlooked insights in oxybenzoate-based liquid crystal polymer materials.
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Affiliation(s)
- Jinxing Li
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China.,Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Runli Xia
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Hao Xu
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Jidan Yang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Xinxin Zhang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Junichi Kougo
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China.,Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Huanyu Lei
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Shuqi Dai
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Houbing Huang
- School of Materials Science & Engineering, and Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Guangzu Zhang
- School of Optical and Electronic Information, and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Fangjie Cen
- School of Optical and Electronic Information, and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Yuanbin Jiang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China.,Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Mingjun Huang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China.,Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
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46
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Spontaneous helielectric nematic liquid crystals: Electric analog to helimagnets. Proc Natl Acad Sci U S A 2021; 118:2111101118. [PMID: 34642251 DOI: 10.1073/pnas.2111101118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2021] [Indexed: 11/18/2022] Open
Abstract
Recently, a type of ferroelectric nematic fluid has been discovered in liquid crystals in which the molecular polar nature at molecule level is amplified to macroscopic scales through a ferroelectric packing of rod-shaped molecules. Here, we report on the experimental proof of a polar chiral liquid matter state, dubbed helielectric nematic, stabilized by the local polar ordering coupled to the chiral helicity. This helielectric structure carries the polar vector rotating helically, analogous to the magnetic counterpart of helimagnet. The helielectric state can be retained down to room temperature and demonstrates gigantic dielectric and nonlinear optical responses. This matter state opens a new chapter for developing the diverse polar liquid crystal devices.
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47
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Brown S, Cruickshank E, Storey JMD, Imrie CT, Pociecha D, Majewska M, Makal A, Gorecka E. Multiple Polar and Non-polar Nematic Phases. Chemphyschem 2021; 22:2506-2510. [PMID: 34623724 DOI: 10.1002/cphc.202100644] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/08/2021] [Indexed: 11/09/2022]
Abstract
Liquid-crystal materials exhibiting up to three nematic phases are reported. Dielectric response measurements show that while the lower temperature nematic phase has ferroelectric order and the highest temperature nematic phase is apolar, the intermediate phase has local antiferroelectric order. The modification of the molecular structure by increasing the number of lateral fluorine substituents leads to one of the materials showing a direct isotropic- ferronematic phase transition.
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Affiliation(s)
- Stevie Brown
- Department of Chemistry, University of Aberdeen, Old Aberdeen, AB24 3UE, U.K
| | - Ewan Cruickshank
- Department of Chemistry, University of Aberdeen, Old Aberdeen, AB24 3UE, U.K
| | - John M D Storey
- Department of Chemistry, University of Aberdeen, Old Aberdeen, AB24 3UE, U.K
| | - Corrie T Imrie
- Department of Chemistry, University of Aberdeen, Old Aberdeen, AB24 3UE, U.K
| | - Damian Pociecha
- Department of Chemistry, University of Warsaw, Zwirki i Wigury 101, 02-089, Warsaw, Poland
| | - Magdalena Majewska
- Department of Chemistry, University of Warsaw, Zwirki i Wigury 101, 02-089, Warsaw, Poland
| | - Anna Makal
- 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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48
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Nishikawa H, Araoka F. A New Class of Chiral Nematic Phase with Helical Polar Order. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101305. [PMID: 34278630 DOI: 10.1002/adma.202101305] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/25/2021] [Indexed: 06/13/2023]
Abstract
A novel chiral nematic phase with a polar helical order is realized via the introduction of helical twisting power into a polar nematogen. The properties of the induced polar nematic (polar cholesteric: Np*) phase differ from those of the conventional cholesteric (N*) phases existing thus far. Np*, which is a new class of N* structures, is characterized not only by its helically twisted nematic director, but also by a continuously twisted polarization. Transmission spectroscopy and helical pitch measurements in a wedge cell revealed that the half-helical pitch in the Np* phase vanished because of the polar response in the Np* helix. The inner polar director in the Np* phase is confirmed in dielectric and second-harmonic-generation studies. Furthermore, this unique Np*LC, which corresponds to a half-/full-pitch helix, enables ultrafast electro-optic switching (τ < 20 µs), and proposes new potential applications for electrically interchangeable photonic bandgaps.
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Affiliation(s)
- Hiroya Nishikawa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Fumito Araoka
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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49
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Madhusudana NV. Simple molecular model for ferroelectric nematic liquid crystals exhibited by small rodlike mesogens. Phys Rev E 2021; 104:014704. [PMID: 34412337 DOI: 10.1103/physreve.104.014704] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/28/2021] [Indexed: 11/07/2022]
Abstract
Nematic liquid crystals (NLCs) are the prime example of a liquid medium with an apolar orientational order. In the past couple of years, the ferroelectric nematic (FN) phase has been discovered in some compounds with small rodlike molecules with large longitudinal dipole moments and very restricted chemical structures, as the temperature is lowered from the NLC. We propose a simple model in which the molecules are idealized as cylindrical rods with longitudinal surface charge density waves. The usually strong electrostatic inter-rod interactions favoring antiparallel structures are shown to be subdued in magnitude, and those of parallel structures enhanced, by reducing the amplitudes of the half-waves at both ends of the rods. By introducing an additional increased amplitude of one interior wave, the energy per rod of a cluster of molecules with a pseudohexagonal order is shown to favor the ferroelectric order compared to the antiparallel order, below some value of the inter-rod separation. The model broadly accounts for the restriction in molecular structures for a compound to exhibit the FN phase. It is suggested that the weakly first-order nature of the NLC to FN transition arises from a coupling of the polar order and the density of the medium.
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Affiliation(s)
- N V Madhusudana
- Raman Research Institute, C.V. Raman Avenue, Bengaluru 560080, India
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50
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Mandle RJ, Sebastián N, Martinez-Perdiguero J, Mertelj A. On the molecular origins of the ferroelectric splay nematic phase. Nat Commun 2021; 12:4962. [PMID: 34400645 PMCID: PMC8367997 DOI: 10.1038/s41467-021-25231-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 07/13/2021] [Indexed: 11/25/2022] Open
Abstract
Nematic liquid crystals have been known for more than a century, but it was not until the 60s–70s that, with the development of room temperature nematics, they became widely used in applications. Polar nematic phases have been long-time predicted, but have only been experimentally realized recently. Synthesis of materials with nematic polar ordering at room temperature is certainly challenging and requires a deep understanding of its formation mechanisms, presently lacking. Here, we compare two materials of similar chemical structure and demonstrate that just a subtle change in the molecular structure enables denser packing of the molecules when they exhibit polar order, which shows that reduction of excluded volume is in the origin of the polar nematic phase. Additionally, we propose that molecular dynamics simulations are potent tools for molecular design in order to predict, identify and design materials showing the polar nematic phase and its precursor nematic phases. Nematic liquid crystals with polar order bear great potential for many applications but their rational design is difficult. Mandle et al. outline a set of design principles for this new phase of matter, guided by experiments and simulation, showing polar order to be driven by steric interactions.
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Affiliation(s)
- Richard J Mandle
- School of Physics and Astronomy, University of Leeds, Leeds, UK. .,Department of Chemistry, University of York, York, UK.
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