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Systematic investigation of the influence of experimental conditions on TiO2 nanosheet structures. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2020.125716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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2
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Jenz F, Osipov MA, Jagiella S, Giesselmann F. Orientational distribution functions and order parameters in "de Vries"-type smectics: A simulation study. J Chem Phys 2016; 145:134901. [PMID: 27782446 DOI: 10.1063/1.4963660] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Simple smectic A liquid crystal phases with different types of prescribed orientational distribution functions have been simulated and compared in order to study the possibility to distinguish between the Maier-Saupe type and cone-like orientational distributions using the popular method of Davidson et al. [J. Phys. II 5, 113 (1995)]. This method has been used to extract the orientational distribution functions from simulated diffraction patterns, and the results have been compared with actual distribution functions which have been prescribed during simulations. It has been shown that it is indeed possible to distinguish between these two qualitatively different types of orientational distribution already from the shape of the 2D diffraction pattern. Moreover, typical experimental diffraction patterns for "de Vries"-type smectic liquid crystals appear to be close to the ones which have been simulated using the prescribed Maier-Saupe orientational distribution function.
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Affiliation(s)
- Frank Jenz
- Institute of Physical Chemistry, Pfaffenwaldring 55, University of Stuttgart, Stuttgart, Germany
| | - Mikhail A Osipov
- Department of Mathematics and Statistics, G1 1XH, University of Strathclyde, Glasgow, United Kingdom
| | - Stefan Jagiella
- Institute of Physical Chemistry, Pfaffenwaldring 55, University of Stuttgart, Stuttgart, Germany
| | - Frank Giesselmann
- Institute of Physical Chemistry, Pfaffenwaldring 55, University of Stuttgart, Stuttgart, Germany
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Jenz F, Jagiella S, Glaser MA, Giesselmann F. Reliability of Orientational Order Parameters Determined from Two-dimensional X-ray Diffraction Patterns: A Simulation Study. Chemphyschem 2016; 17:1568-72. [PMID: 26928989 DOI: 10.1002/cphc.201600050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Indexed: 11/09/2022]
Abstract
The orientational order parameter S2 is one of the most important quantities to describe the degree of long-range orientational ordering of liquid crystals. There are several approaches to experimentally measure this order parameter of liquid crystalline phases but every method includes substantial simplifications and assumptions. We present a simulation-based approach to elucidate the reliability of the method of Davidson, Petermann and Levelut to measure S2 via 2D X-ray experiments. We have found that this method slightly underestimates S2 by an absolute value of only 0.05 and thus provides reliable measures of S2 by X-ray diffraction.
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Affiliation(s)
- Frank Jenz
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Stefan Jagiella
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Matthew A Glaser
- Department of Physics, 390 UCB, University of Colorado, Boulder, CO, 80309-0390, USA
| | - Frank Giesselmann
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
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Varga S, Martínez-Ratón Y, Velasco E, Bautista-Carbajal G, Odriozola G. Effect of orientational restriction on monolayers of hard ellipsoids. Phys Chem Chem Phys 2016; 18:4547-56. [PMID: 26796794 DOI: 10.1039/c5cp05702g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of out-of-plane orientational freedom on the orientational ordering properties of a monolayer of hard ellipsoids is studied using the Parsons-Lee scaling approach and replica exchange Monte Carlo computer simulation. Prolate and oblate ellipsoids exhibit very different ordering properties, namely, the axes of revolution of prolate particles tend to lean out, while those of oblate ones prefer to lean into the confining plane. The driving mechanism of this is that the particles try to maximize the available free area on the confining surface, which can be achieved by minimizing the cross section areas of the particles with the plane. In the lack of out-of-plane orientational freedom the monolayer of prolate particles is identical to a two-dimensional hard ellipse system, which undergoes an isotropic-nematic ordering transition with increasing density. With gradually switching on the out-of-plane orientational freedom the prolate particles lean out from the confining plane and destabilisation of the in-plane isotropic-nematic phase transition is observed. The system of oblate particles behaves oppositely to that of prolates. It corresponds to a two-dimensional system of hard disks in the lack of out-of-plane freedom, while it behaves similar to that of hard ellipses in the freely rotating case. Solid phases can be realised by lower surface coverage due to the out-of-plane orientation freedom for both oblate and prolate shapes.
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Affiliation(s)
- Szabolcs Varga
- Institute of Physics and Mechatronics, University of Pannonia, PO Box 158, Veszprém, H-8201 Hungary
| | - Yuri Martínez-Ratón
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matemáticas, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911, Leganés, Madrid, Spain
| | - Enrique Velasco
- Departamento de Física Teórica de la Materia Condensada and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Gustavo Bautista-Carbajal
- Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, 09340, México, Distrito Federal, Mexico and Academia de Matemáticas, Universidad Autónoma de la Ciudad de México, 07160, México, D. F., Mexico
| | - Gerardo Odriozola
- Area de Física de Procesos Irreversibles, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, 02200 México, D. F., Mexico.
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González-Pinto M, Martínez-Ratón Y, Velasco E, Varga S. Effect of shape biaxiality on the phase behavior of colloidal liquid-crystal monolayers. Phys Chem Chem Phys 2015; 17:6389-400. [PMID: 25655742 DOI: 10.1039/c4cp04812a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We extend our previous work on monolayers of uniaxial particles [J. Chem. Phys., 2014, 140, 204906] to study the effect of particle biaxiality on the phase behavior of liquid-crystal monolayers. Particles are modelled as board-like hard bodies with three different edge lengths σ1 ≥ σ2 ≥ σ3, and the restricted-orientation approximation (Zwanzig model) is used. A density-functional formalism based on the fundamental-measure theory is used to calculate phase diagrams for a wide range of values with the largest aspect ratio κ1 = σ1/σ3 ∈ [1,100]. We find that particle biaxiality in general destabilizes the biaxial nematic phase already present in monolayers of uniaxial particles. While plate-like particles exhibit strong biaxial ordering, rod-like ones with κ1 > 21.34 exhibit reentrant uniaxial and biaxial phases. As particle geometry is changed from uniaxial- to increasingly biaxial-rod-like, the region of biaxiality is reduced, eventually ending in a critical-end point. For κ1 > 60, a density gap opens up in which the biaxial nematic phase is stable for any particle biaxiality. Regions of the phase diagram, where packing-fraction inversion occurs (i.e. packing fraction is a decreasing function of density), are found. Our results are compared with the recent experimental studies on nematic phases of magnetic nanorods.
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Affiliation(s)
- Miguel González-Pinto
- Departamento de Física Teórica de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
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Comparative investigations of phase states, mesomorphic and morphologic properties in hexadecyltrimethyl ammonium bromide/water and hexadecyltrimethyl ammonium bromide/water/1-decanol lyotropic liquid crystalline systems. J Mol Liq 2014. [DOI: 10.1016/j.molliq.2014.10.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Slyusarenko K, Constantin D, Davidson P. A two-dimensional nematic phase of magnetic nanorods. J Chem Phys 2014; 140:104904. [DOI: 10.1063/1.4867790] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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LamellarLαMesophases Doped with Inorganic Nanoparticles. Chemphyschem 2014; 15:1270-82. [DOI: 10.1002/cphc.201301187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Indexed: 11/07/2022]
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Structural peculiarities of micelles in lamellar mesophase of lyotropic liquid crystalline systems: Shape, sizes and anisometricity. J Mol Liq 2013. [DOI: 10.1016/j.molliq.2013.08.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Saliba S, Mingotaud C, Kahn ML, Marty JD. Liquid crystalline thermotropic and lyotropic nanohybrids. NANOSCALE 2013; 5:6641-6661. [PMID: 23817742 DOI: 10.1039/c3nr01175e] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This review is meant to give the reader an insight into hybrids incorporating different types of nanoparticles, e.g. metallic or metal oxides, within different types of lyotropic and thermotropic liquid crystals, from relatively small calamitic molecules to the larger discotics and polymers. In particular, this review highlights the importance of nanoparticle-liquid crystal interactions in accessing hybrid materials that exhibit synergetic properties.
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Affiliation(s)
- Sarmenio Saliba
- Laboratoire IMRCP, CNRS UMR 5623, University of Toulouse, 118, route de Narbonne, 31062, Toulouse, France
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Slyusarenko K, Reshetnyak V, Reznikov Y. Magnetic field control of the ordering of two-component suspension of hard rods. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120250. [PMID: 23459956 DOI: 10.1098/rsta.2012.0250] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The Onsager theory of hard rod dispersion in a neutral solvent is extended to a case of two-component dispersion consisting of both non-magnetic and magnetic rods. It was found that the alignment of magneto-sensitive dispersion component by a magnetic field leads to the alignment of non-magnetic component in the dispersion and to an elimination of the isotropic phase. This effect is significant even at low relative concentrations of magnetic rods and leads to a magnetically induced anisotropy in a non-magnetic dispersion of rods mixed with the magnetic ones.
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Affiliation(s)
- K Slyusarenko
- Laboratoire de Physique des Solides CNRS, Université Paris-Sud, Orsay, France
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Halls JE, Wright KJ, Pickersgill JE, Smith JP, Altalhi AA, Bourne RW, Alaei P, Ramakrishnappa T, Kelly SM, Wadhawan JD. Voltammetry within structured liquid nanosystems: Towards the design of a flexible, three-dimensional framework for artificial photosystems. Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2012.03.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Acharya DP, Moffat BA, Polyzos A, Waddington L, Coia G, Wright DK, Wang HX, Egan GF, Muir BW, Hartley PG. Cubic mesophase nanoparticles doped with superparamagnetic iron oxide nanoparticles: a new class of MRI contrast agent. RSC Adv 2012. [DOI: 10.1039/c2ra20135f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Vallooran JJ, Bolisetty S, Mezzenga R. Macroscopic alignment of lyotropic liquid crystals using magnetic nanoparticles. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:3932-3937. [PMID: 21793053 DOI: 10.1002/adma.201101760] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Jijo J Vallooran
- ETH Zurich, Food and Soft Materials Science, Institute of Food, Nutrition and Health, Zurich, Switzerland
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Venugopal E, Bhat SK, Vallooran JJ, Mezzenga R. Phase behavior of lipid-based lyotropic liquid crystals in presence of colloidal nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:9792-9800. [PMID: 21749073 DOI: 10.1021/la201767p] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have investigated the microstructure and phase behavior of monoglyceride-based lyotropic liquid crystals in the presence of hydrophilic silica colloidal particles of size comparable to or slightly exceeding the repeat units of the different liquid crystalline phases. Using small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC), we compare the structural properties of the neat mesophases with those of the systems containing silica colloidal particles. It is found that the colloidal particles always macrophase separate in inverse bicontinuous cubic phases of gyroid (Ia3d) and double diamond (Pn3m) symmetries. SAXS data for the inverse columnar hexagonal phase (H(II)) and lamellar phase (L(α)) suggest that a low volume fraction of the nanoparticles can be accommodated within the mesophases, but that at concentrations above a given threshold, the particles do macrophase separate also in these systems. The behavior is interpreted in terms of the enthalpic and entropic interactions of the nanoparticles with the lamellar and hexagonal phases, and we propose that, in the low concentration limit, the nanoparticles are acting as point defects within the mesophases and, upon further increase in concentration, initiate nucleation of nanoparticles clusters, leading to a macroscopic phase separation.
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Affiliation(s)
- Edakkal Venugopal
- Complex Fluids and Polymer Engineering, National Chemical Laboratory, Pune 411008, India
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