1
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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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2
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Marchenko AA, Kapitanchuk OL, Lopatina YY, Nazarenko KG, Senenko AI, Katsonis N, Nazarenko VG, Lavrentovich OD. Polar Self-Organization of Ferroelectric Nematic-Liquid-Crystal Molecules on Atomically Flat Au(111) Surface. PHYSICAL REVIEW LETTERS 2024; 132:098101. [PMID: 38489655 DOI: 10.1103/physrevlett.132.098101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/15/2023] [Accepted: 01/26/2024] [Indexed: 03/17/2024]
Abstract
Understanding nanoscale mechanisms responsible for the recently discovered ferroelectric nematics can be helped by direct visualization of self-assembly of strongly polar molecules. Here, we report on scanning tunneling microscopy studies of monomolecular layers of a ferroelectric nematic liquid crystal on a reconstructed Au(111) surface. The monolayers are obtained by deposition from a solution at ambient conditions. The adsorbed ferroelectric nematic molecules self-assemble into regular rows with tilted orientation, resembling a layered structure of a smectic C. Remarkably, each molecular dipole in this architecture is oriented along the same direction giving rise to polar ferroelectric ordering.
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Affiliation(s)
- Alexandr A Marchenko
- Institute of Physics of the National Academy of Sciences of Ukraine, 46 Nauki Avenue, Kyiv 03028, Ukraine
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Oleksiy L Kapitanchuk
- Bogolyubov Institute for Theoretical Physics of the National Academy of Sciences of Ukraine, 14-B Metrologichna Street, Kyiv 03143, Ukraine
| | - Yaroslava Yu Lopatina
- Institute of Physics of the National Academy of Sciences of Ukraine, 46 Nauki Avenue, Kyiv 03028, Ukraine
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Kostiantyn G Nazarenko
- Institute of Organic Chemistry of the National Academy of Sciences of Ukraine, 5 Academician Kukhar St., Kyiv 02660, Ukraine
- Ukraine Enamine Ltd., 78 Winston Churchill St., Kyiv 02094, Ukraine
| | - Anton I Senenko
- Institute of Physics of the National Academy of Sciences of Ukraine, 46 Nauki Avenue, Kyiv 03028, Ukraine
| | - Nathalie Katsonis
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Vassili G Nazarenko
- Institute of Physics of the National Academy of Sciences of Ukraine, 46 Nauki Avenue, Kyiv 03028, Ukraine
- Institute of Physical Chemistry, PAS, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Department of Physics, Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, USA
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3
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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 DOI: 10.1038/s41598-024-54832-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [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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4
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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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5
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Yu JS, Lee JH, Lee JY, Kim JH. Alignment properties of a ferroelectric nematic liquid crystal on the rubbed substrates. SOFT MATTER 2023; 19:2446-2453. [PMID: 36939059 DOI: 10.1039/d3sm00123g] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The orientation characteristics of FNLC-919, a new material with a ferroelectric nematic phase at room temperature, were investigated. Its alignment characteristics varied greatly depending on the relative rubbing direction on both substrates of a liquid crystal cell. In a cell where the two substrates were rubbed in the same direction, they were arranged homogeneously along the rubbing direction without domains or defects in the ferroelectric nematic phase. In a cell where the two substrates were rubbed in the anti-parallel direction, the two domains were twisted in the opposite direction. We quantitatively obtained the twisted direction and angle by matching the experimental data and calculation results using Jones matrix calculations. From the electro-optical experiment, it was confirmed that the polarization direction was opposite to the rubbing direction. In addition, the wavelength and temperature dependence of birefringence was measured for FNLC-919. In a cell where the rubbing direction between two substrates was 90°, two domains of opposite directions were observed in the nematic phase. When it becomes a ferroelectric nematic phase on cooling, the twist is determined to be only in one direction. The twist direction and angle were quantitatively obtained in the nematic and ferroelectric nematic phases. It was twisted more in the ferroelectric nematic phase than in the nematic phase.
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Affiliation(s)
- Jeong-Seon Yu
- Institute of Quantum Systems, Chungnam National University, Daejeon, 34134, Korea.
| | - Jae Hoon Lee
- Department of Physics, Chungnam National University, Daejeon, 34134, Korea
| | - Jun-Yong Lee
- Department of Physics, Chungnam National University, Daejeon, 34134, Korea
| | - Jong-Hyun Kim
- Institute of Quantum Systems, Chungnam National University, Daejeon, 34134, Korea.
- Department of Physics, Chungnam National University, Daejeon, 34134, Korea
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6
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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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7
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Kumari P, Basnet B, Wang H, Lavrentovich OD. Ferroelectric nematic liquids with conics. Nat Commun 2023; 14:748. [PMID: 36765061 PMCID: PMC9918734 DOI: 10.1038/s41467-023-36326-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 01/23/2023] [Indexed: 02/12/2023] Open
Abstract
Spontaneous electric polarization of solid ferroelectrics follows aligning directions of crystallographic axes. Domains of differently oriented polarization are separated by domain walls (DWs), which are predominantly flat and run along directions dictated by the bulk translational order and the sample surfaces. Here we explore DWs in a ferroelectric nematic (NF) liquid crystal, which is a fluid with polar long-range orientational order but no crystallographic axes nor facets. We demonstrate that DWs in the absence of bulk and surface aligning axes are shaped as conic sections. The conics bisect the angle between two neighboring polarization fields to avoid electric charges. The remarkable bisecting properties of conic sections, known for millennia, play a central role as intrinsic features of liquid ferroelectrics. The findings could be helpful in designing patterns of electric polarization and space charge.
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Affiliation(s)
- Priyanka Kumari
- grid.258518.30000 0001 0656 9343Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242 USA ,grid.258518.30000 0001 0656 9343Materials Science Graduate Program, Kent State University, Kent, OH 44242 USA
| | - Bijaya Basnet
- grid.258518.30000 0001 0656 9343Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242 USA ,grid.258518.30000 0001 0656 9343Materials Science Graduate Program, Kent State University, Kent, OH 44242 USA
| | - Hao Wang
- grid.258518.30000 0001 0656 9343Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242 USA
| | - Oleg D. Lavrentovich
- grid.258518.30000 0001 0656 9343Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242 USA ,grid.258518.30000 0001 0656 9343Materials Science Graduate Program, Kent State University, Kent, OH 44242 USA ,grid.258518.30000 0001 0656 9343Department of Physics, Kent State University, Kent, OH 44242 USA
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8
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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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9
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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: 4] [Impact Index Per Article: 2.0] [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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10
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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: 27] [Impact Index Per Article: 13.5] [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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11
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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: 14] [Impact Index Per Article: 7.0] [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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