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Drozd-Rzoska A, Łoś J, Rzoska SJ. The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4'-butylaniline with Transverse Permanent Dipole Moment and BaTiO 3 Nanoparticles. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:655. [PMID: 38668149 PMCID: PMC11053839 DOI: 10.3390/nano14080655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/03/2024] [Accepted: 04/07/2024] [Indexed: 04/29/2024]
Abstract
The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO3 nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4'-butylaniline) is a liquid crystalline compound with a permanent dipole moment transverse to the long molecular axis. The distortions-sensitive analysis of the dielectric constant revealed its hidden pretransitional anomaly, strongly influenced by the addition of nanoparticles. The evolution of the dielectric constant in the nematic phase shows the split into two regions, with the crossover coinciding with the standard melting temperature. The 'universal' exponential-type behavior of the low-frequency contribution to the real part of the dielectric permittivity is found. The critical-like pretransitional behavior in the solid phase is also evidenced. This is explained by linking the Lipovsky model to the Mossotti catastrophe concept under quasi-negative pressure conditions. The explicit preference for the 'critical-like' evolution of the apparent activation enthalpy is worth stressing for dynamics. Finally, the long-range, 'critical-like' behavior of the dissipation factor (D = tgδ), covering the isotropic liquid and nematic phases, is shown.
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Affiliation(s)
| | | | - Sylwester J. Rzoska
- Institute of High Pressure Physics, Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland; (A.D.-R.); (J.Ł.)
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Rani A, Chakraborty S, Sinha A. Effect of CdSe/ZnS quantum dot dispersion on phase transitional behavior of 8OCB liquid crystal. Phys Rev E 2023; 108:034701. [PMID: 37849204 DOI: 10.1103/physreve.108.034701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 07/10/2023] [Indexed: 10/19/2023]
Abstract
We report the effect on the phase transitional behavior of 8OCB liquid crystal (LC) doped with functionalized CdSe/ZnS quantum dots (QDs) in different concentrations. The temperature-dependent data of high-resolution optical birefringence and dielectric anisotropy are utilized to characterize the critical anomaly for both the isotropic-to-nematic (I-N) and nematic-to-smectic-A (N-SmA) phase transitions. The obtained results reveal that the order parameter exponent (β) for the pure LC is found to be β=0.249 and does not vary upon the inclusion of QDs in the pure matrix. It describes the weakly first-order characteristic of the I-N phase transition for all the studied samples, which falls within the limit of the tricritical hypothesis. Conversely, depending on the range of the N phase, we observed a nonuniversal nature of the specific heat capacity critical exponent (α^{'}) linked with the N-SmA phase transition for all the studied samples. A relative comparison was made amongst the α^{'} values extracted from both the anisotropy data, and further, a theoretical relationship is established with these exponent values. The coupling strength among the N and SmA order parameters is determined using the optical birefringence data and discussed from the perspective of mutual interaction between the LC-QDs ligands. The results signify that a strong ligand-ligand interaction between neighboring QDs effectively reduces the N range and slightly influences the N-SmA phase transition.
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Affiliation(s)
- Aysha Rani
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Susanta Chakraborty
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Aloka Sinha
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Łoś J, Drozd-Rzoska A, Rzoska S. Critical-like behavior of low-frequency dielectric properties in compressed liquid crystalline octyloxycyanobiphenyl (8OCB) and its nanocolloid with paraelectric BaTiO3. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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Phase Equilibria and Critical Behavior in Nematogenic MBBA-Isooctane Monotectic-Type Mixtures. Int J Mol Sci 2023; 24:ijms24032065. [PMID: 36768388 PMCID: PMC9916662 DOI: 10.3390/ijms24032065] [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: 12/23/2022] [Revised: 01/16/2023] [Accepted: 01/18/2023] [Indexed: 01/21/2023] Open
Abstract
The transition from the isotropic (I) liquid to the nematic-type (N) uniaxial phase appearing as the consequence of the elongated geometry of elements seems to be a universal phenomenon for many types of suspensions, from solid nano-rods to biological particles based colloids. Rod-like thermotropic nematogenic liquid crystalline (LC) compounds and their mixtures with a molecular solvent (Sol) can be a significant reference for this category, enabling insights into universal features. The report presents studies in 4'-methoxybenzylidene-4-n-butylaniline (MBBA) and isooctane (Sol) mixtures, for which the monotectic-type phase diagram was found. There are two biphasic regions (i) for the low (TP1, isotropic liquid-nematic coexistence), and (ii) high (TP2, liquid-liquid coexistence) concentrations of isooctane. For both domains, biphasic coexistence curves' have been discussed and parameterized. For TP2 it is related to the order parameter and diameter tests. Notable is the anomalous mean-field type behavior near the critical consolute temperature. Regarding the isotropic liquid phase, critical opalescence has been detected above both biphasic regions. For TP2 it starts ca. 20 K above the critical consolute temperature. The nature of pretransitional fluctuations in the isotropic liquid phase was tested via nonlinear dielectric effect (NDE) measurements. It is classic (mean-field) above TP1 and non-classic above the TP2 domain. The long-standing problem regarding the non-critical background effect was solved to reach this result.
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Łoś J, Drozd-Rzoska A, Rzoska SJ, Czupryński K. The impact of ionic contribution to dielectric permittivity in 11CB liquid crystal and its colloids with BaTiO 3 nanoparticles. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2022; 45:74. [PMID: 36074208 PMCID: PMC9458595 DOI: 10.1140/epje/s10189-022-00228-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/24/2022] [Indexed: 06/15/2023]
Abstract
The report shows the temperature behavior of the real part of dielectric permittivity in the static (dielectric constant) and low-frequency (LF) domains in bulk samples of 11CB and its BaTiO3-based nanocolloids. The study covers the isotropic liquid (I), nematic (N), smectic A (SmA), and solid crystal (Cr) phases. For each phase, the dominance of pretransitional fluctuations, significantly moderated by nanoparticles, is shown. The authors consider separate focuses on the dielectric constant [Formula: see text] evolution in the static domain, yielding mainly response from permanent dipole moment and its arrangement, and in the low-frequency (LF) domain [Formula: see text] (where [Formula: see text] is for the real part of dielectric permittivity in the LF domain), which is associated solely with ionic-related polarization mechanisms. All of these led to new experimental evidence concerning I-N, N-SmA, and SmA-solid transitions, focusing on the strength and extent of pretransitional effects, critical exponents, and phase transitions discontinuities. The strong evidence for pretransitional effects near the SmA-Cr transition is notable, particularly regarding [Formula: see text]. Studies are supplemented by the discussion of DC electric conductivity-a parameter also related to the LF domain. Finally, the validity of the relation [Formula: see text] (where f stands for frequency, and A is a constant parameter), often used for discussing dielectric spectra in LC compound and its nanocolloids in the LF domain, is examined.
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Affiliation(s)
- Joanna Łoś
- Institute of High Pressure Physics, Polish Academy of Sciences, X-PressMatter Lab, ul. Sokołowska 29/37, 01-142, Warsaw, Poland.
| | - Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics, Polish Academy of Sciences, X-PressMatter Lab, ul. Sokołowska 29/37, 01-142, Warsaw, Poland
| | - Sylwester J Rzoska
- Institute of High Pressure Physics, Polish Academy of Sciences, X-PressMatter Lab, ul. Sokołowska 29/37, 01-142, Warsaw, Poland
| | - Krzysztof Czupryński
- Faculty of Advanced Technologies and Chemistry, Military University of Technology, ul. gen. Sylwestra Kaliskiego 2, 00-908, Warsaw, Poland
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Łoś J, Drozd-Rzoska A, Rzoska SJ, Starzonek S, Czupryński K. The fluctuation-driven dielectric properties of liquid crystalline 8OCB and its nanocolloids. SOFT MATTER 2022; 18:4502-4512. [PMID: 35678229 DOI: 10.1039/d2sm00105e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Results of broadband dielectric spectroscopy studies in liquid crystalline octyloxycyanobiphenyl (8OCB) and its colloids with BaTiO3 nanoparticles (paraelectric, diameter d = 50 nm) are presented. Studies were carried out in isotropic liquid, nematic, smectic A and solid crystalline phases. They are supported by derivative-based and distortion-sensitive analyses, revealing a set of universal scaling patterns for temperature evolution of static and dynamic dielectric properties. All these yielded evidence for a pretransitional fluctuation impact on the dielectric constant, primary relaxation time, loss curve maximum and translational-orientational decoupling associated with anomalous values of the fractional Debye-Stokes-Einstein (DSE) exponent 0.2 < S < 2.2. The evidence for critical like changes in a distribution of relaxation times is shown. For mesophases, a tiny addition of nanoparticles causes permanent orientation of LC molecules, leading even to a 16% increase of the dielectric constant above a maximal value in pure 8OCB. A split of two regions, dominated by pre-isotropic and pre-smectic fluctuations, is evidenced. Model explanations for detected phenomena, particularly in the isotropic liquid phase, are presented. New evidence for a premelting effect in the solid phase is also shown.
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Affiliation(s)
- Joanna Łoś
- Institute of High Pressure Physics of the Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland.
| | - Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics of the Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland.
| | - Sylwester J Rzoska
- Institute of High Pressure Physics of the Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland.
| | - Szymon Starzonek
- Institute of High Pressure Physics of the Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland.
| | - Krzysztof Czupryński
- Military University of Technology, ul. gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland
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Parveen A, Prakash J, Singh G. Impact of strontium titanate nanoparticles on the dielectric, electro-optical and electrical response of a nematic liquid crystal. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118907] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Effect of Liquid Crystalline Host on Structural Changes in Magnetosomes Based Ferronematics. NANOMATERIALS 2021; 11:nano11102643. [PMID: 34685084 PMCID: PMC8537930 DOI: 10.3390/nano11102643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/06/2021] [Accepted: 10/06/2021] [Indexed: 12/23/2022]
Abstract
The effect of the liquid crystalline host on structural changes in magnetosomes based on ferronematics is studied using the surface acoustic wave (SAW) technique supported by some capacitance and light transmission measurements. The measurement of the attenuation response of SAW propagating along the interface between LC and the piezoelectric substrate is used to study processes of structural changes under magnetic field. The magnetosome nanoparticles of the same volume concentration were added to three different nematic LCs, 5CB, 6CB, and E7. Unlike to undoped LCs, the different responses of SAW attenuation under the influence of magnetic and electric fields in LCs doped with magnetosomes were observed due to characteristic structural changes. The decrease of the threshold field for doped LCs as compared with pure LCs and slight effects on structural changes were registered. The threshold magnetic fields of LCs and composites were determined from capacitance measurements, and the slight shift to lower values was registered for doped LCs. The shift of nematic-isotropic transition was registered from dependencies of SAW attenuation on temperature. The acoustic anisotropy measurement approved the previous supposition about the role of bulk viscosity in used SAW measurements. In addition, capacitance and light transmition investigations supported SAW results and pointed out conclusions about their magnetic field behavior. Obtained results are discussed and confronted with previous ones and coincide well with those observed using acoustic, optical, or dielectric techniques.
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Roy S, Chen YL. Rich phase transitions in strongly confined polymer-nanoparticle mixtures: Nematic ordering, crystallization, and liquid-liquid phase separation. J Chem Phys 2021; 154:024901. [PMID: 33445888 DOI: 10.1063/5.0034602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the rich phase behavior of strongly confined semi-flexible (SFC) polymer-nanoparticle (NP) systems using the graphics processing unit accelerated Langevin dynamics simulation. Hard nanoparticles (HNP) that repel each other and ideal nanoparticles (INP) that do not interact with the same species are used as model additives to a strongly confined semiflexible polymer fluid. Both types of NPs exclude the monomer beads in the same way, but they have qualitatively different effects on the SFC isotropic-nematic (I-N) transition. For the total volume fraction ϕtot < 0.16, adding a low volume fraction of HNPs (ϕp) disrupts the long range nematic order of the polymers, whereas adding HNPs in a moderately packed system (0.16 < ϕtot < 0.32) facilitates polymer alignment due to the restricted polymer orientational degree of freedom. For dense packing (ϕtot > 0.32), polymers and NPs separate into layers along the slit height and the NPs form crystalline microdomains. In contrast, INP additives always promote inter-polymer alignment for low to moderate monomer volume fractions (ϕm). Furthermore, we found that INPs form a droplet-like fluid domain in dense nematic polymer systems.
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Affiliation(s)
- Supriya Roy
- Institute of Physics, Academia Sinica, Taipei, Taiwan
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Rzoska SJ, Starzonek S, Łoś J, Drozd-Rzoska A, Kralj S. Dynamics and Pretransitional Effects in C 60 Fullerene Nanoparticles and Liquid Crystalline Dodecylcyanobiphenyl (12CB) Hybrid System. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2343. [PMID: 33255904 PMCID: PMC7761475 DOI: 10.3390/nano10122343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/15/2020] [Accepted: 11/16/2020] [Indexed: 11/16/2022]
Abstract
The report shows the strong impact of fullerene C60 nanoparticles on phase transitions and complex dynamics of rod-like liquid crystal dodecylcyanobiphenyl (12CB), within the limit of small concentrations. Studies were carried out using broadband dielectric spectroscopy (BDS) via the analysis of temperature dependences of the dielectric constant, the maximum of the primary loss curve, and relaxation times. They revealed a strong impact of nanoparticles, leading to a ~20% change of dielectric constant even at x = 0.05% of C60 fullerene. The application of the derivative-based and distortion-sensitive analysis showed that pretransitional effects dominate in the isotropic liquid phase up to 65 K above the clearing temperature and in the whole Smectic A mesophase. The impact of nanoparticles on the pretransitional anomaly appearance is notable for the smectic-solid phase transition. The fragility-based analysis of relaxation times revealed the universal pattern of its temperature changes, associated with scaling via the "mixed" ("activated" and "critical") relation. Phase behavior and dynamics of tested systems are discussed within the extended Landau-de Gennes-Ginzburg mesoscopic approach.
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Affiliation(s)
- Sylwester J. Rzoska
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Szymon Starzonek
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Joanna Łoś
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Samo Kralj
- Laboratory of Physics of Complex Systems, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia;
- Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
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Suppression of the reentrant nematic and stabilization of the smectic phases by carbon nanotubes. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.04.135] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Drozd-Rzoska A, Starzonek S, Rzoska SJ, Kralj S. Nanoparticle-controlled glassy dynamics in nematogen-based nanocolloids. Phys Rev E 2019; 99:052703. [PMID: 31212529 DOI: 10.1103/physreve.99.052703] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Indexed: 11/07/2022]
Abstract
Results of broad-band dielectric spectroscopy studies in liquid crystal (pentylcyanobiphenyl, 5CB)-based nanocolloids are presented. They reveal the strong impact of BaTiO_{3} nanoparticles on dynamics and uniaxial ordering. Studies were carried out in an extreme range of temperatures (∼150 K), including the supercooled nematic phase. For the latter, the unique "pretransitional" effect for dielectric constant on approaching solid state is reported. The distortion-sensitive analysis revealed super-Arrhenius dynamics but associated with critical-like behavior. In the isotropic phase, translational-orientational decoupling, unusual for the high temperature dynamic domain, was detected. It can be directly link to heterogeneities-prenematic fluctuations. The model linking the classical Landau-de Gennes approach with Imry-Ma arguments has been developed to discuss experimental results.
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Affiliation(s)
- Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics of the Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland
| | | | | | - Samo Kralj
- Faculty of Natural Sciences and Mathematics, University of Maribor, Koroska 160, 2000 Maribor, Slovenia and Condensed Matter Physics Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
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Abstract
Dilute mixtures of nanoparticles (NPs) and nematic liquid crystals (LCs) are considered. We focus on cases where NPs enforce a relatively weak disorder to the LC host. We use a Lebwohl-Lasher semi-microscopic-type modeling where we assume that NPs effectively act as a spatially-dependent external field on nematic spins. The orientational distribution of locally favoured “easy” orientations is described by a probabilistic distribution function P. By means of a mean field-type approach, we derive a self-consistent equation for the average degree of nematic uniaxial order parameter S as a function of the concentration p of NPs, NP-LC coupling strength and P. Using a simple step-like probability distribution shape, we obtain the S(p) dependence displaying a crossover behaviour between two different regimes which is in line with recent experimental observations. We also discuss a possible origin of commonly observed non-monotonous variations of the nematic-isotropic phase temperature coexistence width on varying p.
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Mrukiewicz M, Perkowski P, Strzeżysz O, Węgłowska D, Piecek W. Pretransitional effects in a mesogenic mixture under an electric field. Phys Rev E 2018; 97:052704. [PMID: 29906921 DOI: 10.1103/physreve.97.052704] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Indexed: 11/07/2022]
Abstract
Nematogenic liquids are materials that are in high demand for many application purposes. Field-induced nematic order in isotropic liquids can be observed by the enhancement of electric permittivity during dielectric spectroscopy measurements under the bias electric field. For this reason, dielectric measurements were done on a nematogenic mixture of highly polar compounds. This paper presents a discussion on the influence of the bias electric field on the dielectric response. We observed a decrease of electric permittivity in the isotropic phase under the bias electric field. This effect is most likely caused by the field-induced creation of some complex molecular objects. In the paper, relaxation parameters of the molecular modes were analyzed. The field-induced orientational order was determined using a dichroic ratio in a guest-host system. The measurements show the significant order parameter in the isotropic phase under an electric field.
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Affiliation(s)
- Mateusz Mrukiewicz
- Institute of Applied Physics, Military University of Technology, 2 Urbanowicza, 00-908 Warsaw, Poland
| | - Paweł Perkowski
- Institute of Applied Physics, Military University of Technology, 2 Urbanowicza, 00-908 Warsaw, Poland
| | - Olga Strzeżysz
- Institute of Chemistry, Military University of Technology, 2 Urbanowicza, 00-908 Warsaw, Poland
| | - Dorota Węgłowska
- Institute of Chemistry, Military University of Technology, 2 Urbanowicza, 00-908 Warsaw, Poland
| | - Wiktor Piecek
- Institute of Applied Physics, Military University of Technology, 2 Urbanowicza, 00-908 Warsaw, Poland
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Garbovskiy Y, Glushchenko A. Ferroelectric Nanoparticles in Liquid Crystals: Recent Progress and Current Challenges. NANOMATERIALS 2017; 7:nano7110361. [PMID: 29104276 PMCID: PMC5707578 DOI: 10.3390/nano7110361] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 10/24/2017] [Accepted: 10/24/2017] [Indexed: 12/21/2022]
Abstract
The dispersion of ferroelectric nanomaterials in liquid crystals has recently emerged as a promising way for the design of advanced and tunable electro-optical materials. The goal of this paper is a broad overview of the current technology, basic physical properties, and applications of ferroelectric nanoparticle/liquid crystal colloids. By compiling a great variety of experimental data and discussing it in the framework of existing theoretical models, both scientific and technological challenges of this rapidly developing field of liquid crystal nanoscience are identified. They can be broadly categorized into the following groups: (i) the control of the size, shape, and the ferroelectricity of nanoparticles; (ii) the production of a stable and aggregate-free dispersion of relatively small (~10 nm) ferroelectric nanoparticles in liquid crystals; (iii) the selection of liquid crystal materials the most suitable for the dispersion of nanoparticles; (iv) the choice of appropriate experimental procedures and control measurements to characterize liquid crystals doped with ferroelectric nanoparticles; and (v) the development and/or modification of theoretical and computational models to account for the complexity of the system under study. Possible ways to overcome the identified challenges along with future research directions are also discussed.
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Affiliation(s)
- Yuriy Garbovskiy
- UCCS Biofrontiers Center and Department of Physics, University of Colorado Colorado Springs, Colorado Springs, CO 80918, USA.
| | - Anatoliy Glushchenko
- Department of Physics, University of Colorado Colorado Springs, Colorado Springs, CO 80918, USA.
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Starzonek S, Rzoska SJ, Drozd-Rzoska A, Czupryński K, Kralj S. Impact of ferroelectric and superparaelectric nanoparticles on phase transitions and dynamics in nematic liquid crystals. Phys Rev E 2017; 96:022705. [PMID: 28950608 DOI: 10.1103/physreve.96.022705] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Indexed: 11/07/2022]
Abstract
Results of broadband dielectric spectroscopy (BDS) studies of pure liquid crystalline (4-pentyloxy-4-biphenylcarbonitryle) 5OCB and its nanocolloids with BaTiO_{3} nanoparticles (NPs) under varying pressure and temperature are presented. The notable impact of NPs on phase transitions and dynamics was found. Particularly strong impact on pretransitional behavior was observed for relatively low concentrations of NPs, which can be related to the NPs-induced disorder. There are also notable differences between pressure and temperature paths of studies for nanocomposites, absent for the pure LC compound. For instance, tests focused on the translational orientational decoupling via the fractional Debye-Stokes-Einstein relation yielded S=0.71 and S=0.3 for the temperature and pressure paths, respectively: S=1 is for the complete coupling. The possible theoretical frame of observed phenomena is also proposed.
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Affiliation(s)
- Szymon Starzonek
- Institute of High Pressure Physics of Polish Academy of Sciences, ulica Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Sylwester J Rzoska
- Institute of High Pressure Physics of Polish Academy of Sciences, ulica Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics of Polish Academy of Sciences, ulica Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Krzysztof Czupryński
- Military University of Technology, Institute of Chemistry, ulica Kaliskiego 2, 00-908 Warsaw, Poland
| | - Samo Kralj
- Condensed Matter Physics Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia and Faculty of Natural Sciences and Mathematics, University of Maribor, Koroska 160, 2000 Maribor, Slovenia
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K. Mukherjee P. Effect of ferroelectric nanoparticles on the dielectric permittivity in the isotropic phase of the isotropic-smectic-A phase transition. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2016.11.122] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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