1
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Li Z, Raab A, Kolmangadi MA, Busch M, Grunwald M, Demel F, Bertram F, Kityk AV, Schönhals A, Laschat S, Huber P. Self-Assembly of Ionic Superdiscs in Nanopores. ACS NANO 2024; 18:14414-14426. [PMID: 38760015 PMCID: PMC11155240 DOI: 10.1021/acsnano.4c01062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 04/23/2024] [Accepted: 05/01/2024] [Indexed: 05/19/2024]
Abstract
Discotic ionic liquid crystals (DILCs) consist of self-assembled superdiscs of cations and anions that spontaneously stack in linear columns with high one-dimensional ionic and electronic charge mobility, making them prominent model systems for functional soft matter. Compared to classical nonionic discotic liquid crystals, many liquid crystalline structures with a combination of electronic and ionic conductivity have been reported, which are of interest for separation membranes, artificial ion/proton conducting membranes, and optoelectronics. Unfortunately, a homogeneous alignment of the DILCs on the macroscale is often not achievable, which significantly limits the applicability of DILCs. Infiltration into nanoporous solid scaffolds can, in principle, overcome this drawback. However, due to the experimental challenges to scrutinize liquid crystalline order in extreme spatial confinement, little is known about the structures of DILCs in nanopores. Here, we present temperature-dependent high-resolution optical birefringence measurement and 3D reciprocal space mapping based on synchrotron X-ray scattering to investigate the thermotropic phase behavior of dopamine-based ionic liquid crystals confined in cylindrical channels of 180 nm diameter in macroscopic anodic aluminum oxide membranes. As a function of the membranes' hydrophilicity and thus the molecular anchoring to the pore walls (edge-on or face-on) and the variation of the hydrophilic-hydrophobic balance between the aromatic cores and the alkyl side chain motifs of the superdiscs by tailored chemical synthesis, we find a particularly rich phase behavior, which is not present in the bulk state. It is governed by a complex interplay of liquid crystalline elastic energies (bending and splay deformations), polar interactions, and pure geometric confinement and includes textural transitions between radial and axial alignment of the columns with respect to the long nanochannel axis. Furthermore, confinement-induced continuous order formation is observed in contrast to discontinuous first-order phase transitions, which can be quantitatively described by Landau-de Gennes free energy models for liquid crystalline order transitions in confinement. Our observations suggest that the infiltration of DILCs into nanoporous solids allows tailoring their nanoscale texture and ion channel formation and thus their electrical and optical functionalities over an even wider range than in the bulk state in a homogeneous manner on the centimeter scale as controlled by the monolithic nanoporous scaffolds.
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Affiliation(s)
- Zhuoqing Li
- Institute
for Materials and X-ray Physics, Hamburg
University of Technology, Denickestr. 15, 21073 Hamburg, Germany
- Centre
for X-ray and Nano Science CXNS, Deutsches
Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Aileen Raab
- Institut
für Organische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Mohamed Aejaz Kolmangadi
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
| | - Mark Busch
- Institute
for Materials and X-ray Physics, Hamburg
University of Technology, Denickestr. 15, 21073 Hamburg, Germany
- Centre
for X-ray and Nano Science CXNS, Deutsches
Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Marco Grunwald
- Institut
für Organische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Felix Demel
- Institut
für Organische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Florian Bertram
- Deutsches
Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Andriy V. Kityk
- Faculty of
Electrical Engineering, Czestochowa University
of Technology, Al. Armii
Krajowej 17, 42-200 Czestochowa, Poland
| | - Andreas Schönhals
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
- Institut
für Chemie, Technische Universität
Berlin, Straße des
17. Juni 135, 10623 Berlin, Germany
| | - Sabine Laschat
- Institut
für Organische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Patrick Huber
- Institute
for Materials and X-ray Physics, Hamburg
University of Technology, Denickestr. 15, 21073 Hamburg, Germany
- Centre
for X-ray and Nano Science CXNS, Deutsches
Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
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2
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Hernandez JJ, Anokhin DV, Rosenthal M, Zhu X, Ivanov DA. Homeotropic orientation of an ion-channel forming mesophase induced by nanotemplate wetting. Phys Chem Chem Phys 2024; 26:13412-13419. [PMID: 38647047 DOI: 10.1039/d3cp05392j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Anodic aluminum oxide (AAO) membranes were used as templates to control orientation of an ion-channel forming columnar mesophase obtained by self assembly of a wedge-shaped sulfonate molecule. Inside the AAO structure, the director vector of the mesophase is oriented parallel to the pore axis due to the confinement effect. The molecular arrangement induced by the spatial confinement within the pores is extended over several microns into the remnant film on the AAO surface. The homeotropic alignment of the channels promotes unidimensional ion conduction through the film plane, which is manifested by a considerable increase in conductivity relative to isotropic samples.
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Affiliation(s)
- Jaime J Hernandez
- Institut de Sciences des Matériaux de Mulhouse (IS2M), CNRS UMR 7361, 15, rue Jean Starcky, F-68057 Mulhouse, France.
| | - Denis V Anokhin
- Faculty of Chemistry, Lomonosov Moscow State University (MSU), GSP-1, 1-3 Leninskiye Gory, 119991, Russian Federation
- Scientific Center for Genetics and Life Sciences, Sirius University of Science and Technology, 1 Olympic Ave., 354340 Sochi, Russian Federation
| | - Martin Rosenthal
- Institut de Sciences des Matériaux de Mulhouse (IS2M), CNRS UMR 7361, 15, rue Jean Starcky, F-68057 Mulhouse, France.
| | - Xiaomin Zhu
- College of Textile Science and Engineering (International Institute of Silk), Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Dimitri A Ivanov
- Institut de Sciences des Matériaux de Mulhouse (IS2M), CNRS UMR 7361, 15, rue Jean Starcky, F-68057 Mulhouse, France.
- Faculty of Chemistry, Lomonosov Moscow State University (MSU), GSP-1, 1-3 Leninskiye Gory, 119991, Russian Federation
- Scientific Center for Genetics and Life Sciences, Sirius University of Science and Technology, 1 Olympic Ave., 354340 Sochi, Russian Federation
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3
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Ou-Yang X, Huang YC, Chi YC, Egashira M, Yang HC, Chen HH. Hexa- peri-hexabenzocoronene derivatives carrying dovetailed alkyl and diacetylenic side chains: a synthesis, characterization, and polymerization study. Polym Chem 2023. [DOI: 10.1039/d2py01171a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A new polymerizable 2,8,14-triphenylhexabenzo[bc,ef,hi,kl,no,qr]coronene (HBC) mesogen bearing alternating dovetailed and linear alkyl chains with a diacetylenic unit were successfully synthesized in this study.
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Affiliation(s)
- Xing Ou-Yang
- College of Materials and Engineering, Shenzhen University, Shenzhen, China
| | - Yi-Cin Huang
- Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan
- Institute of Organic and Polymeric Materials, Research and Development Center of Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan
| | - Ying-Chi Chi
- Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan
- Institute of Organic and Polymeric Materials, Research and Development Center of Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan
| | - Mayumi Egashira
- Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan
- Institute of Organic and Polymeric Materials, Research and Development Center of Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan
| | - Hao-Chun Yang
- Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan
- Institute of Organic and Polymeric Materials, Research and Development Center of Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan
| | - Hsiu-Hui Chen
- Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan
- Institute of Organic and Polymeric Materials, Research and Development Center of Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan
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4
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Dreier P, Pipertzis A, Spyridakou M, Mathes R, Floudas G, Frey H. Introduction of Trifluoromethanesulfonamide Groups in Poly(ethylene oxide): Ionic Conductivity of Single-Ion-Conducting Block Copolymer Electrolytes. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Philip Dreier
- Department of Chemistry, Johannes Gutenberg University Mainz, Mainz 55099, Germany
| | | | | | - Robin Mathes
- Department of Chemistry, Johannes Gutenberg University Mainz, Mainz 55099, Germany
| | - George Floudas
- Department of Physics, University of Ioannina, Ioannina 45110, Greece
- Max Planck Institute for Polymer Research, Mainz 55128, Germany
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), Ioannina 45110, Greece
| | - Holger Frey
- Department of Chemistry, Johannes Gutenberg University Mainz, Mainz 55099, Germany
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5
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Kityk AV, Gor GY, Huber P. Adsorption from binary liquid solutions into mesoporous silica: a capacitance isotherm on 5CB nematogen/cyclohexane mixtures. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1909160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Andriy V. Kityk
- Institute for Materials and X-Ray Physics, Hamburg University of Technology, Hamburg, Germany
- Faculty of Electrical Engineering, Czestochowa University of Technology, Czestochowa, Poland
| | - Gennady Y. Gor
- Otto H. York Department Chemical and Materials Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ, USA
| | - Patrick Huber
- Institute for Materials and X-Ray Physics, Hamburg University of Technology, Hamburg, Germany
- High-Resolution X-Ray Analytics of Materials Research Group, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- Centre for Hybrid Nanostructures CHyN, Hamburg University, Hamburg, Germany
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6
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Theodoridis A, Papamokos G, Wiesenfeldt MP, Wollenburg M, Müllen K, Glorius F, Floudas G. Polarity Matters: Dielectric Relaxation in All- cis-Multifluorinated Cycloalkanes. J Phys Chem B 2021; 125:3700-3709. [PMID: 33818098 DOI: 10.1021/acs.jpcb.1c00100] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The polarity of all-cis-multifluorinated cyclohexanes can be fine-tuned by the number and relative orientation of fluoro substituents, giving rise to a series of compounds with strong dipole moments. Simulations provided the energetics, the dipole moments, and the respective molecular polarizabilities, while dielectric spectroscopy gave information on the dielectric permittivities and the molecular dynamics. In special cases, dipole moments in excess of 6 D and dielectric permittivities of over 300 were obtained by simulation and experiment. Melting temperatures within a given family of multifluorinated cyclohexanes were found to scale with the molecular volume. The less-symmetric all-cis-octafluorotetrahydronaphthalene did not readily crystallize, permitting an investigation of the molecular dynamics in an energetically unfavorable yet rigid and facially polarized isomer. The resulting dynamics above the glass temperature conform to the structural α-relaxation and to the celebrated Johari-Goldstein β-relaxation.
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Affiliation(s)
| | - George Papamokos
- Department of Physics, University of Ioannina, 451 10 Ioannina, Greece
| | - Mario P Wiesenfeldt
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Marco Wollenburg
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Klaus Müllen
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Frank Glorius
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - George Floudas
- Department of Physics, University of Ioannina, 451 10 Ioannina, Greece.,University Research Center of Ioannina (URCI), Institute of Materials Science and Computing, 451 10 Ioannina, Greece
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7
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Elmahdy MM, Gournis D, Ladavos A, Spanos C, Floudas G. H-Shaped Copolymer of Polyethylene and Poly(ethylene oxide) under Severe Confinement: Phase State and Dynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4261-4271. [PMID: 32243167 DOI: 10.1021/acs.langmuir.0c00127] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The self-assembly and the dynamics of an H-shaped copolymer composed of a polyethylene midblock and four poly(ethylene oxide) arms (PE-b-4PEO) are investigated in the bulk and under severe confinement into nanometer-spaced LAPONITE clay particles by means of small- and wide-angle X-ray diffraction (SAXS, WAXS), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), rheology, and dielectric spectroscopy (DS). Because of the H-shaped architecture, the PE midblock is topologically frustrated and thus unable to crystallize. The superstructure formation in the bulk is dictated solely by the PEO arms as inferred by the crystallization/melting temperature relative to the PEO homopolymer. Confinement produced remarkable changes in the interlayer distance and PEO crystallinity but left the local segmental dynamics unaltered. To reconcile all structural, thermodynamic, and dynamic effects, a novel morphological picture is proposed with interest in emulsions. Key parameters that stabilize the final morphology are the severe chain confinement with the associated entropy loss and the presence of interactions (hydrophobic/hydrophilic) between the LAPONITE and the PEO/PE blocks.
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Affiliation(s)
- Mahdy M Elmahdy
- Department of Physics, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt
- Department of Physics, University of Ioannina, 451 10 Ioannina, Greece
| | - Dimitrios Gournis
- Department of Materials Science & Engineering, University of Ioannina, 45110 Ioannina, Greece
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 451 10 Ioannina, Greece
| | - Athanasios Ladavos
- Department of Business Administration of Food and Agricultural Enterprises, University of Patras, 30100 Agrinio, Greece
| | - Christos Spanos
- Department of Business Administration of Food and Agricultural Enterprises, University of Patras, 30100 Agrinio, Greece
| | - George Floudas
- Department of Physics, University of Ioannina, 451 10 Ioannina, Greece
- Max Planck Institute for Polymer Research, D-55128 Mainz, Germany
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 451 10 Ioannina, Greece
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8
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Sentker K, Yildirim A, Lippmann M, Zantop AW, Bertram F, Hofmann T, Seeck OH, Kityk AV, Mazza MG, Schönhals A, Huber P. Self-assembly of liquid crystals in nanoporous solids for adaptive photonic metamaterials. NANOSCALE 2019; 11:23304-23317. [PMID: 31788679 DOI: 10.1039/c9nr07143a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanoporous media exhibit structures significantly smaller than the wavelengths of visible light and can thus act as photonic metamaterials. Their optical functionality is not determined by the properties of the base materials, but rather by tailored, multiscale structures, in terms of precise pore shape, geometry, and orientation. Embedding liquid crystals in pore space provides additional opportunities to control light-matter interactions at the single-pore, meta-atomic scale. Here, we present temperature-dependent 3D reciprocal space mapping using synchrotron-based X-ray diffraction in combination with high-resolution birefringence experiments on disk-like mesogens (HAT6) imbibed in self-ordered arrays of parallel cylindrical pores 17 to 160 nm across in monolithic anodic aluminium oxide (AAO). In agreement with Monte Carlo computer simulations we observe a remarkably rich self-assembly behaviour, unknown from the bulk state. It encompasses transitions between the isotropic liquid state and discotic stacking in linear columns as well as circular concentric ring formation perpendicular and parallel to the pore axis. These textural transitions underpin an optical birefringence functionality, tuneable in magnitude and in sign from positive to negative via pore size, pore surface-grafting and temperature. Our study demonstrates that the advent of large-scale, self-organised nanoporosity in monolithic solids along with confinement-controllable phase behaviour of liquid-crystalline matter at the single-pore scale provides a reliable and accessible tool to design materials with adjustable optical anisotropy, and thus offers versatile pathways to fine-tune polarisation-dependent light propagation speeds in materials. Such a tailorability is at the core of the emerging field of transformative optics, allowing, e.g., adjustable light absorbers and extremely thin metalenses.
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Affiliation(s)
- Kathrin Sentker
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany.
| | - Arda Yildirim
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, D-12205 Berlin, Germany
| | - Milena Lippmann
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Arne W Zantop
- Max-Planck-Institute for Dynamics and Self-Organization, Am Faßberg 17, D-37077 Göttingen, Germany
| | - Florian Bertram
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Tommy Hofmann
- Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany
| | - Oliver H Seeck
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Andriy V Kityk
- Faculty of Electrical Engineering, Czestochowa University of Technology, 42-200 Czestochowa, Poland.
| | - Marco G Mazza
- Max-Planck-Institute for Dynamics and Self-Organization, Am Faßberg 17, D-37077 Göttingen, Germany and Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
| | - Andreas Schönhals
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, D-12205 Berlin, Germany
| | - Patrick Huber
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany.
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9
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Selevou A, Papamokos G, Yildirim T, Duran H, Steinhart M, Floudas G. Eutectic liquid crystal mixture E7 in nanoporous alumina. Effects of confinement on the thermal and concentration fluctuations. RSC Adv 2019; 9:37846-37857. [PMID: 35541799 PMCID: PMC9075738 DOI: 10.1039/c9ra08806g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 11/11/2019] [Indexed: 11/21/2022] Open
Abstract
The eutectic mixture of liquid crystals E7 is studied in confinement by means of thermal and dielectric measurements. The uniform 1-D confinement provided by self-ordered nanoporous alumina leads to a decrease in the nematic to isotropic transition temperature due to interaction with the pore surface, e.g. surface anchoring. The prevalence of certain dynamic modes of relaxation is found to depend on the surface properties of the confining pores. The dynamics (i.e., relaxation times) were found to accelerate with increasing confinement, resulting in a decreasing glass temperature, independent of surface treatment. From the pre- and meta-transitional dependence of the dielectric permittivity on temperature we are able to deduce a weakening effect of confinement on the nematic to isotropic (N/I) transition which allows the determination of a critical pore diameter (in the range from 11 nm to 23 nm) below which the transition becomes continuous. Comparison of the N/I transition of E7 to those of its constituent liquid crystals reveals a significantly weaker transition occurring over a widened temperature range. This suggest the importance of concentration fluctuations in rounding first order phase transitions that are triggered by the different length scales and ranges of nematic stability in E7. The results have an impact beyond the present case and for several soft materials (e.g. oligomers used as OLEDs, polymers, colloids) as it demonstrates the importance of concentration fluctuations in addition to thermal fluctuation on the strength of phase transitions.
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Affiliation(s)
- Aristoula Selevou
- Department of Physics, University of Ioannina P. O. Box 1186 451 10 Ioannina Greece
| | - George Papamokos
- Department of Physics, University of Ioannina P. O. Box 1186 451 10 Ioannina Greece
| | - Tolga Yildirim
- Department of Materials Science & Nanotechnology Engineering, TOBB University of Economics and Technology Söğütözü Cad. 43 Ankara 06560 Turkey
| | - Hatice Duran
- Department of Materials Science & Nanotechnology Engineering, TOBB University of Economics and Technology Söğütözü Cad. 43 Ankara 06560 Turkey
| | - Martin Steinhart
- Institut für Chemie Neuer Materialien, Universität Osnabrück D-49069 Osnabrück Germany
| | - George Floudas
- Department of Physics, University of Ioannina P. O. Box 1186 451 10 Ioannina Greece
- University Research Center of Ioannina (URCI), Institute of Materials Science and Computing Ioannina Greece
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10
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Park W, Feringán B, Yang M, Ryu SH, Ahn H, Shin TJ, Sierra T, Giménez R, Yoon DK. Manipulation of Supramolecular Columnar Structures of H-Bonded Donor-Acceptor Units through Geometrical Nanoconfinement. Chemphyschem 2019; 20:890-897. [PMID: 30730103 DOI: 10.1002/cphc.201801042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/23/2018] [Indexed: 11/12/2022]
Abstract
Ambipolar organic semiconductors are considered promising for organic electronics because of their interesting electric properties. Many hurdles remain yet to be overcome before they can be used for practical applications, especially because their orientation is hard to control. We demonstrate a method to control the orientation of columnar structures based on a hydrogen (H)-bonded donor-acceptor complex between a star-shaped tris(triazolyl)triazine and triphenylene-containing benzoic acid, using physicochemical nanoconfinement. The molecular configuration and supramolecular columnar assemblies in a one-dimensional porous anodic aluminium oxide (AAO) film were dramatically modulated by controlling the pore-size and by chemical modification of the inner surface of the porous AAO film. In situ experiments using grazing-incidence X-ray diffraction (GIXRD) were carried out to investigate the structural evolution produced at the nanometer scale by varying physicochemical conditions. The resulting highly ordered nanostructures may open a new pathway to effectively control the alignment of liquid crystal ambipolar semiconductors.
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Affiliation(s)
- Wongi Park
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Beatriz Feringán
- Departamento de Química Orgánica Instituto de Ciencia de Materiales de Aragón (ICMA) Facultad de Ciencias, Universidad de Zaragoza-CSIC, Zaragoza, 50009, Spain
| | - Minyong Yang
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Seong Ho Ryu
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Hyungju Ahn
- Pohang Accelerator Laboratory, POSTECH, Pohang, 37673, Republic of Korea
| | - Tae Joo Shin
- UNIST Central Research Facilities and, School of Natural Science UNIST, Ulsan, 44919, Republic of Korea
| | - Teresa Sierra
- Departamento de Química Orgánica Instituto de Ciencia de Materiales de Aragón (ICMA) Facultad de Ciencias, Universidad de Zaragoza-CSIC, Zaragoza, 50009, Spain
| | - Raquel Giménez
- Departamento de Química Orgánica Instituto de Ciencia de Materiales de Aragón (ICMA) Facultad de Ciencias, Universidad de Zaragoza-CSIC, Zaragoza, 50009, Spain
| | - Dong Ki Yoon
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.,Department of Chemistry and KINC, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
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11
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Zou C, Wang J, Wang M, Wu Y, Gu K, Shen Z, Xiong G, Yang H, Jiang L, Ikeda T. Patterning of Discotic Liquid Crystals with Tunable Molecular Orientation for Electronic Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1800557. [PMID: 29667319 DOI: 10.1002/smll.201800557] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/07/2018] [Indexed: 06/08/2023]
Abstract
The large-area formation of functional micropatterns with liquid crystals is of great significance for diversified applications in interdisciplinary fields. Meanwhile, the control of molecular alignment in the patterns is fundamental and prerequisite for the adequate exploitation of their photoelectric properties. However, it would be extremely complicated and challenging for discotic liquid crystals (DLCs) to achieve the goal, because they are insensitive to external fields and surface chemistry. Herein, a simple method of patterning and aligning DLCs on flat substrates is disclosed through precise control of the formation and dewetting of the capillary liquid bridges, within which the DLC molecules are confined. Large-area uniform alignment occurs spontaneously due to directional shearing force when the solvent is slowly evaporated and programmable patterns could be directly generated on desired substrates. Moreover, the in-plane column direction of DLCs is tunable by slightly tailoring their chemical structures which changes their self-assembly behaviors in liquid bridges. The patterned DLCs show molecular orientation-dependent charge transport properties and are promising for templating self-assembly of other materials. The study provides a facile method for manipulation of the macroscopic patterns and microscopic molecular orientation which opens up new opportunities for electronic applications of DLCs.
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Affiliation(s)
- Cheng Zou
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, P. R. China
| | - Jingxia Wang
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Meng Wang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, P. R. China
| | - Yuchen Wu
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Kehua Gu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Zhihao Shen
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Guirong Xiong
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Huai Yang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Tomiki Ikeda
- Research and Development Initiative, Chuo University, Tokyo, 112-8551, Japan
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12
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Sentker K, Zantop AW, Lippmann M, Hofmann T, Seeck OH, Kityk AV, Yildirim A, Schönhals A, Mazza MG, Huber P. Quantized Self-Assembly of Discotic Rings in a Liquid Crystal Confined in Nanopores. PHYSICAL REVIEW LETTERS 2018; 120:067801. [PMID: 29481274 DOI: 10.1103/physrevlett.120.067801] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/21/2017] [Indexed: 05/16/2023]
Abstract
Disklike molecules with aromatic cores spontaneously stack up in linear columns with high, one-dimensional charge carrier mobilities along the columnar axes, making them prominent model systems for functional, self-organized matter. We show by high-resolution optical birefringence and synchrotron-based x-ray diffraction that confining a thermotropic discotic liquid crystal in cylindrical nanopores induces a quantized formation of annular layers consisting of concentric circular bent columns, unknown in the bulk state. Starting from the walls this ring self-assembly propagates layer by layer towards the pore center in the supercooled domain of the bulk isotropic-columnar transition and thus allows one to switch on and off reversibly single, nanosized rings through small temperature variations. By establishing a Gibbs free energy phase diagram we trace the phase transition quantization to the discreteness of the layers' excess bend deformation energies in comparison to the thermal energy, even for this near room-temperature system. Monte Carlo simulations yielding spatially resolved nematic order parameters, density maps, and bond-orientational order parameters corroborate the universality and robustness of the confinement-induced columnar ring formation as well as its quantized nature.
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Affiliation(s)
- Kathrin Sentker
- Institut für Materialphysik und -technologie, Technische Universität Hamburg (TUHH), Eißendorferstr. 42, D-21073 Hamburg, Germany
| | - Arne W Zantop
- Max-Planck-Institut für Dynamik und Selbstorganisation, Am Faßberg 17, D-37077 Göttingen, Germany
| | - Milena Lippmann
- Deutsches Elektronen Synchrotron (DESY), Notkestraße 85, D-22607 Hamburg, Germany
| | - Tommy Hofmann
- Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
| | - Oliver H Seeck
- Deutsches Elektronen Synchrotron (DESY), Notkestraße 85, D-22607 Hamburg, Germany
| | - Andriy V Kityk
- Faculty of Electrical Engineering, Czestochowa University of Technology, Al. Armii Krajowej 17, P-42-200 Czestochowa, Poland
| | - Arda Yildirim
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, D-12205 Berlin, Germany
| | - Andreas Schönhals
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, D-12205 Berlin, Germany
| | - Marco G Mazza
- Max-Planck-Institut für Dynamik und Selbstorganisation, Am Faßberg 17, D-37077 Göttingen, Germany
| | - Patrick Huber
- Institut für Materialphysik und -technologie, Technische Universität Hamburg (TUHH), Eißendorferstr. 42, D-21073 Hamburg, Germany
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13
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Huang LB, Xu W, Hao J. Energy Device Applications of Synthesized 1D Polymer Nanomaterials. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:1701820. [PMID: 28961368 DOI: 10.1002/smll.201701820] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/03/2017] [Indexed: 06/07/2023]
Abstract
1D polymer nanomaterials as emerging materials, such as nanowires, nanotubes, and nanopillars, have attracted extensive attention in academia and industry. The distinctive, various, and tunable structures in the nanoscale of 1D polymer nanomaterials present nanointerfaces, high surface-to-volume ratio, and large surface area, which can improve the performance of energy devices. In this review, representative fabrication techniques of 1D polymer nanomaterials are summarized, including electrospinning, template-assisted, template-free, and inductively coupled plasma methods. The recent advancements of 1D polymer nanomaterials in energy device applications are demonstrated. Lastly, existing challenges and prospects of 1D polymer nanomaterials for energy device applications are presented.
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Affiliation(s)
- Long-Biao Huang
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Wei Xu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China
| | - Jianhua Hao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, China
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14
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Yao Y, Suzuki Y, Seiwert J, Steinhart M, Frey H, Butt HJ, Floudas G. Capillary Imbibition, Crystallization, and Local Dynamics of Hyperbranched Poly(ethylene oxide) Confined to Nanoporous Alumina. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b01843] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Yang Yao
- Max Planck Institute
for Polymer Research, D-55128 Mainz, Germany
| | - Yasuhito Suzuki
- Max Planck Institute
for Polymer Research, D-55128 Mainz, Germany
| | - Jan Seiwert
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, D-55099 Mainz, Germany
| | - Martin Steinhart
- Institut
für Chemie neuer Materialien, Universität Osnabrück, D-49069 Osnabrück, Germany
| | - Holger Frey
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, D-55099 Mainz, Germany
| | - Hans-Jürgen Butt
- Max Planck Institute
for Polymer Research, D-55128 Mainz, Germany
| | - George Floudas
- Max Planck Institute
for Polymer Research, D-55128 Mainz, Germany
- Department
of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece
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15
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Selevou A, Papamokos G, Steinhart M, Floudas G. 8OCB and 8CB Liquid Crystals Confined in Nanoporous Alumina: Effect of Confinement on the Structure and Dynamics. J Phys Chem B 2017; 121:7382-7394. [DOI: 10.1021/acs.jpcb.7b05042] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Aristoula Selevou
- Department
of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece
| | - George Papamokos
- Department
of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece
| | - Martin Steinhart
- Institut
für Chemie neuer Materialien, Universität Osnabrück, D-49069 Osnabrück, Germany
| | - George Floudas
- Department
of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece
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16
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Zhang RB, Ungar G, Zeng X, Shen Z. Diverse configurations of columnar liquid crystals in cylindrical nano- and micropores. SOFT MATTER 2017; 13:4122-4131. [PMID: 28548148 DOI: 10.1039/c7sm00620a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Using 2D X-ray diffraction and AFM we studied the configuration, in cylindrical confinement, of hexagonal columnar phases that anchor homeotropically, i.e. with the columns normal to the pore wall. A wide range of pore diameters, from 20 nm to 100 μm, were explored by employing anodic alumina membranes and glass capillaries. The compounds used were a small discotic, hexakis(hexyloxy)triphenylene (HAT6), a large discotic hexa-peri-hexabenzocoronene (HBC), and a T-shaped bolaamphiphile, forming a honeycomb-type columnar phase. It was found that in pores up to tens of μm in diameter the columns adopt the "logpile" configuration with parallel columns crossing the pore perpendicular to its axis. Starting with 20 nm pores, with increasing pore diameter up to 5 different configurations are observed, the sequence being the same for all three compounds in spite of their structural diversity. One of the {100} planes of the hexagonal logpile starts from being parallel to the pore axis, then rotates by 90° as the pore size increases, and eventually becomes tilted to the pore axis by (8.5 ± 1)° as the pore widens further. Finally, in glass capillaries of tens of μm and beyond, the columns become axially oriented, parallel to the capillary axis. This latter finding was particularly unexpected as common sense would suggest axial columns to be favoured by planar anchoring, where in fact, it was shown to be hard to achieve. The present findings should help in the design of low-dimensional semiconductor or ionic conductor devices based on oriented columnar phases.
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Affiliation(s)
- Rui-Bin Zhang
- Department of Physics, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou 310018, China.
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17
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Pipertzis A, Zardalidis G, Wunderlich K, Klapper M, Müllen K, Floudas G. Ionic Conduction in Poly(ethylene glycol)-Functionalized Hexa-peri-hexabenzocoronene Amphiphiles. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00224] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Achilleas Pipertzis
- Department
of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece
| | - George Zardalidis
- Department
of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece
| | | | - Markus Klapper
- Max Planck Institute
for Polymer Research, 55128 Mainz, Germany
| | - Klaus Müllen
- Max Planck Institute
for Polymer Research, 55128 Mainz, Germany
| | - George Floudas
- Department
of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece
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18
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Cha YJ, Yoon DK. Control of Periodic Zigzag Structures of DNA by a Simple Shearing Method. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1604247. [PMID: 27862385 DOI: 10.1002/adma.201604247] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/19/2016] [Indexed: 06/06/2023]
Abstract
A periodic zigzag structure of DNA material is successfully fabricated by a simple shearing method. The periodicity of the pattern can be finely controlled by combining the mechanical shearing method with topographic patterns of microchannels. The resultant zigzag patterns can be used as a template to control the alignment of rod-like liquid crystals due to its highly regular periodicity.
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Affiliation(s)
- Yun Jeong Cha
- Graduate School of Nanoscience and Technology and KINC, KAIST, Daejeon, 305-701, Republic of Korea
| | - Dong Ki Yoon
- Graduate School of Nanoscience and Technology and KINC, KAIST, Daejeon, 305-701, Republic of Korea
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19
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Ryu SH, Yoon DK. Molecular Orientation of Liquid Crystals on Topographic Nanopatterns. ACS APPLIED MATERIALS & INTERFACES 2016; 8:17707-17712. [PMID: 27322013 DOI: 10.1021/acsami.6b05568] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Controlling the orientation of building blocks in soft matter on the substrate has been a big challenge in material sciences. We have controlled the molecular orientation of liquid crystal (LC) materials on the porous anodic aluminum oxide (AAO) film having hexagonal pore arrays on the top surface. In our method, anchoring conditions can be varied by changing the pore size (Dp) and the porosity (P). As a proof-of-concept, the orientation of smectic A (SmA) structure at different anchoring conditions was successfully controlled in a sandwich cell consisting of AAO and a glass substrate, which has not been successfully controlled by conventional methods.
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Affiliation(s)
- Seong Ho Ryu
- Graduate School of Nanoscience and Technology and KINC, KAIST , Daejeon 34141, Republic of Korea
| | - Dong Ki Yoon
- Graduate School of Nanoscience and Technology and KINC, KAIST , Daejeon 34141, Republic of Korea
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20
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Bogdanowicz KA, Rapsilber GA, Reina JA, Giamberini M. Liquid crystalline polymeric wires for selective proton transport, part 1: Wires preparation. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.03.073] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Wöhrle T, Wurzbach I, Kirres J, Kostidou A, Kapernaum N, Litterscheidt J, Haenle JC, Staffeld P, Baro A, Giesselmann F, Laschat S. Discotic Liquid Crystals. Chem Rev 2015; 116:1139-241. [PMID: 26483267 DOI: 10.1021/acs.chemrev.5b00190] [Citation(s) in RCA: 422] [Impact Index Per Article: 46.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tobias Wöhrle
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Iris Wurzbach
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Jochen Kirres
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Antonia Kostidou
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Nadia Kapernaum
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Juri Litterscheidt
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Johannes Christian Haenle
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Peter Staffeld
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Angelika Baro
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Frank Giesselmann
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Sabine Laschat
- Institut für Organische Chemie, and ‡Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
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22
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Całus S, Borowik L, Kityk AV, Eich M, Busch M, Huber P. Thermotropic interface and core relaxation dynamics of liquid crystals in silica glass nanochannels: a dielectric spectroscopy study. Phys Chem Chem Phys 2015; 17:22115-24. [PMID: 26255586 DOI: 10.1039/c5cp03039k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report dielectric relaxation spectroscopy experiments on two rod-like liquid crystals of the cyanobiphenyl family (5CB and 6CB) confined in tubular nanochannels with 7 nm radius and 340 micrometer length in a monolithic, mesoporous silica membrane. The measurements were performed on composites for two distinct regimes of fractional filling: monolayer coverage at the pore walls and complete filling of the pores. For the layer coverage a slow surface relaxation dominates the dielectric properties. For the entirely filled channels the dielectric spectra are governed by two thermally-activated relaxation processes with considerably different relaxation rates: a slow relaxation in the interface layer next to the channel walls and a fast relaxation in the core region of the channel filling. The strengths and characteristic frequencies of both relaxation processes have been extracted and analysed as a function of temperature. Whereas the temperature dependence of the static capacitance reflects the effective (average) molecular ordering over the pore volume and is well described within a Landau-de Gennes theory, the extracted relaxation strengths of the slow and fast relaxation processes provide an access to distinct local molecular ordering mechanisms. The order parameter in the core region exhibits a bulk-like behaviour with a strong increase in the nematic ordering just below the paranematic-to-nematic transition temperature TPN and subsequent saturation during cooling. By contrast, the surface ordering evolves continuously with a kink near TPN. A comparison of the thermotropic behaviour of the monolayer with the complete filling reveals that the molecular order in the core region of the pore filling affects the order of the peripheral molecular layers at the wall.
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Affiliation(s)
- Sylwia Całus
- Faculty of Electrical Engineering, Czestochowa University of Technology, 42-200 Czestochowa, Poland.
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23
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Suzuki Y, Steinhart M, Butt HJ, Floudas G. Kinetics of Ice Nucleation Confined in Nanoporous Alumina. J Phys Chem B 2015; 119:11960-6. [PMID: 26241561 DOI: 10.1021/acs.jpcb.5b06295] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nucleation mechanism of water (heterogeneous/homogeneous) can be regulated by confinement within nanoporous alumina. The kinetics of ice nucleation is studied in confinement by employing dielectric permittivity as a probe. Both heterogeneous and homogeneous nucleation, obtained at low and high undercooling, respectively, are stochastic in nature. The temperature interval of metastability extends over ∼4 and 0.4 °C for heterogeneous and homogeneous nucleation, respectively. Nucleation within a pore is spread to all pores in the template. We have examined a possible coupling of all pores through a heat wave and a sound wave, with the latter being a more realistic scenario. In addition, dielectric spectroscopy indicates that prior to crystallization undercooled water molecules relax with an activation energy of ∼50 kJ/mol, and this process acts as precursor to ice nucleation.
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Affiliation(s)
- Yasuhito Suzuki
- Max Planck Institute for Polymer Research , 55128 Mainz, Germany
| | - Martin Steinhart
- Institut für Chemie neuer Materialien, Universität Osnabrück , D-49069 Osnabrück, Germany
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research , 55128 Mainz, Germany
| | - George Floudas
- Department of Physics, University of Ioannina , 45110 Ioannina, Greece
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24
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Całus S, Kityk AV, Borowik L, Lefort R, Morineau D, Krause C, Schönhals A, Busch M, Huber P. High-resolution dielectric study reveals pore-size-dependent orientational order of a discotic liquid crystal confined in tubular nanopores. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:012503. [PMID: 26274191 DOI: 10.1103/physreve.92.012503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Indexed: 05/16/2023]
Abstract
We report a high-resolution dielectric study on a pyrene-based discotic liquid crystal (DLC) in the bulk state and confined in parallel tubular nanopores of monolithic silica and alumina membranes. The positive dielectric anisotropy of the DLC molecule at low frequencies (in the quasistatic case) allows us to explore the thermotropic collective orientational order. A face-on arrangement of the molecular discs on the pore walls and a corresponding radial arrangement of the molecules is found. In contrast to the bulk, the isotropic-to-columnar transition of the confined DLC is continuous, shifts with decreasing pore diameter to lower temperatures, and exhibits a pronounced hysteresis between cooling and heating. These findings corroborate conclusions from previous neutron and x-ray-scattering experiments as well as optical birefringence measurements. Our study also indicates that the relative simple dielectric technique presented here is a quite efficient method in order to study the thermotropic orientational order of DLC-based nanocomposites.
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Affiliation(s)
- Sylwia Całus
- Faculty of Electrical Engineering, Czestochowa University of Technology, 42-200 Czestochowa, Poland
| | - Andriy V Kityk
- Faculty of Electrical Engineering, Czestochowa University of Technology, 42-200 Czestochowa, Poland
| | - Lech Borowik
- Faculty of Electrical Engineering, Czestochowa University of Technology, 42-200 Czestochowa, Poland
| | - Ronan Lefort
- Institut de Physique de Rennes, UMR 6251, Université de Rennes 1, 35042 Rennes, France
| | - Denis Morineau
- Institut de Physique de Rennes, UMR 6251, Université de Rennes 1, 35042 Rennes, France
| | - Christina Krause
- BAM Federal Institute for Materials Research and Testing, D-12203 Berlin, Germany
| | - Andreas Schönhals
- BAM Federal Institute for Materials Research and Testing, D-12203 Berlin, Germany
| | - Mark Busch
- Institute of Materials Physics and Technology, Hamburg University of Technology (TUHH), D-21073 Hamburg-Harburg, Germany
| | - Patrick Huber
- Institute of Materials Physics and Technology, Hamburg University of Technology (TUHH), D-21073 Hamburg-Harburg, Germany
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25
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Całus S, Kityk AV, Eich M, Huber P. Inhomogeneous relaxation dynamics and phase behaviour of a liquid crystal confined in a nanoporous solid. SOFT MATTER 2015; 11:3176-3187. [PMID: 25759093 DOI: 10.1039/c5sm00108k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report filling-fraction dependent dielectric spectroscopy measurements on the relaxation dynamics of the rod-like nematogen 7CB condensed in 13 nm silica nanochannels. In the film-condensed regime, a slow interface relaxation dominates the dielectric spectra, whereas from the capillary-condensed state up to complete filling an additional, fast relaxation in the core of the channels is found. The temperature-dependence of the static capacitance, representative of the averaged, collective molecular orientational ordering, indicates a continuous, paranematic-to-nematic (P-N) transition, in contrast to the discontinuous bulk behaviour. It is well described by a Landau-de-Gennes free energy model for a phase transition in cylindrical confinement. The large tensile pressure of 10 MPa in the capillary-condensed state, resulting from the Young-Laplace pressure at highly curved liquid menisci, quantitatively accounts for a downward-shift of the P-N transition and an increased molecular mobility in comparison to the unstretched liquid state of the complete filling. The strengths of the slow and fast relaxations provide local information on the orientational order: the thermotropic behaviour in the core region is bulk-like, i.e. it is characterized by an abrupt onset of the nematic order at the P-N transition. By contrast, the interface ordering exhibits a continuous evolution at the P-N transition. Thus, the phase behaviour of the entirely filled liquid crystal-silica nanocomposite can be quantitatively described by a linear superposition of these distinct nematic order contributions.
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Affiliation(s)
- Sylwia Całus
- Faculty of Electrical Engineering, Czestochowa University of Technology, Al. Armii Krajowej 17, 42-200 Czestochowa, Poland.
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26
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Huber P. Soft matter in hard confinement: phase transition thermodynamics, structure, texture, diffusion and flow in nanoporous media. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:103102. [PMID: 25679044 DOI: 10.1088/0953-8984/27/10/103102] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculiarities of nanopore-confined condensed matter are also discussed with regard to applications. A particular emphasis is put on texture formation upon crystallisation in nanoporous media, a topic both of high fundamental interest and of increasing nanotechnological importance, e.g. for the synthesis of organic/inorganic hybrid materials by melt infiltration, the usage of nanoporous solids in crystal nucleation or in template-assisted electrochemical deposition of nano structures.
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Affiliation(s)
- Patrick Huber
- Hamburg University of Technology (TUHH), Institute of Materials Physics and Technology, Eißendorfer Str. 42, D-21073 Hamburg-Harburg (Germany
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27
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Suzuki Y, Duran H, Steinhart M, Kappl M, Butt HJ, Floudas G. Homogeneous nucleation of predominantly cubic ice confined in nanoporous alumina. NANO LETTERS 2015; 15:1987-1992. [PMID: 25686014 DOI: 10.1021/nl504855z] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The nucleation mechanism of water can be precisely regulated by confinement within nanoporous alumina. We found a transition from heterogeneous nucleation of hexagonal ice (Ih) to homogeneous nucleation of predominantly cubic ice (Ic) with decreasing pore diameter. These results lead to a phase diagram of water under confinement. It contains a (stable) predominant Ic form, a form known to exist only in the upper atmosphere. Possible applications range from cryopreservation to construction materials like cement.
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Affiliation(s)
- Yasuhito Suzuki
- Max-Planck Institute for Polymer Research , 55128 Mainz, Germany
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28
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Zhang R, Zeng X, Kim B, Bushby RJ, Shin K, Baker PJ, Percec V, Leowanawat P, Ungar G. Columnar liquid crystals in cylindrical nanoconfinement. ACS NANO 2015; 9:1759-1766. [PMID: 25626118 DOI: 10.1021/nn506605p] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Axial orientation of discotic columnar liquid crystals in nanopores of inorganic templates, with the columns parallel to the axis of the nanochannels, is considered desirable for applications such as production of molecular wires. Here, we evaluate experimentally the role of the rigidity of the LC columns in achieving such orientation in nanopores where the planar anchoring (i.e., columns parallel to wall surface) is enforced. We studied the columnar phase of several discotic compounds with increasing column rigidity in the following order: dendronized carbazole, hexakis(hexyloxy)triphenylene (HAT6), a 1:1 HAT6-trinitrofluorenone (TNF) complex, and a helicene derivative. Using 2-D X-ray diffraction, AFM, grazing incidence diffraction, and polarized microscopy, we observed that the orientation of the columns changes from circular concentric to axial with increasing column rigidity. Additionally, when the rigidity is borderline, increasing pore diameter can change the configuration from axial back to circular. We derive expressions for distortion free energy that suggest that the orientation is determined by the competition between, on the one hand, the distortion energy of the 2-d lattice and the mismatch of its crystallographic facets with the curved pore wall in the axial orientation and, on the other hand, the bend energy of the columns in the circular configuration. Furthermore, the highly detailed AFM images of the core of the disclinations of strength +1 and +1/2 in the center of the pore reveal that the columns spiral down to the very center of the disclination and that there is no amorphous or misaligned region at the core, as suggested previously.
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Affiliation(s)
- Ruibin Zhang
- Department of Materials Science and Engineering, University of Sheffield , Sheffield S1 3JD, U.K
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Wang YF, Zhang CX, Wu H, Zhang A, Wang JC, Zhang SF, Pu JL. Modulation of phase behaviors and charge carrier mobilities by linkage length in discotic liquid crystal dimers. SOFT MATTER 2015; 11:712-718. [PMID: 25467212 DOI: 10.1039/c4sm02369b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A clear structure-property relationship was revealed in a series of triphenylene-based dimers, which contained two triphenylene nuclei each bearing five β-OC4H9 substituents and are linked through a flexible O(CH2)nO polymethylene chain (n=6-12). Dimers with the linkage close to twice the length of the free side chains (n=8, 9) exhibited a single Colhp phase, while others with the linkage shorter (n=6, 7) or longer (n=10, 11, 12) showed multiphase behaviors with a transition from the Colhp phase to Colh phase; hole mobilities of Colhp phases reached 1.4×10(-2) cm2 V(-1) s(-1) in the dimer for which the linkage is exactly twice the length of the free side chains (n=8), and decreased regularly both with linkage length becoming shorter or longer. This modulation of phase behaviors and charge carrier mobilities was demonstrated to be generated by various steric perturbations introduced by linkages with different lengths, which result in different degrees of lateral fluctuations of discotic moieties in the columns.
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Affiliation(s)
- Yi-Fei Wang
- Information Recording Materials Lab, Lab of Printing & Packaging Material and Technology, Beijing Institute of Graphic Communication, 102600 Beijing, China.
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Busselez R, Cerclier CV, Ndao M, Ghoufi A, Lefort R, Morineau D. Discotic columnar liquid crystal studied in the bulk and nanoconfined states by molecular dynamics simulation. J Chem Phys 2014; 141:134902. [DOI: 10.1063/1.4896052] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Rémi Busselez
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
- Institut des Molécules et des Matériaux du Mans, UMR-CNRS 6283 Université du Maine, Avenue Olivier Messiaen 72085 Le Mans Cedex 9, France
| | - Carole V. Cerclier
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
- Institut des Matériaux de Nantes (IMN), UMR-CNRS 6502, 2 rue de la Houssiniere, BP32229, 44322 Nantes cedex3, France
| | - Makha Ndao
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
- Institut de Chimie de Clermont-Ferrand (ICCF) - UMR-CNRS 6296, Université Blaise Pascal, Campus des Cézeaux, 63171 Aubiere cedex, France
| | - Aziz Ghoufi
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
| | - Ronan Lefort
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
| | - Denis Morineau
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
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31
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Wunderlich K, Grigoriadis C, Zardalidis G, Klapper M, Graf R, Butt HJ, Müllen K, Floudas G. Poly(ethylene glycol)-Functionalized Hexaphenylbenzenes as Unique Amphiphiles: Supramolecular Organization and Ion Conductivity. Macromolecules 2014. [DOI: 10.1021/ma501303k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - George Zardalidis
- Department
of Physics, University of Ioannina, 45110 Ioannina, Greece
| | - Markus Klapper
- Max-Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Robert Graf
- Max-Planck Institute for Polymer Research, 55128 Mainz, Germany
| | | | - Klaus Müllen
- Max-Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - George Floudas
- Department
of Physics, University of Ioannina, 45110 Ioannina, Greece
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32
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Kityk AV, Busch M, Rau D, Calus S, Cerclier CV, Lefort R, Morineau D, Grelet E, Krause C, Schönhals A, Frick B, Huber P. Thermotropic orientational order of discotic liquid crystals in nanochannels: an optical polarimetry study and a Landau-de Gennes analysis. SOFT MATTER 2014; 10:4522-4534. [PMID: 24832498 DOI: 10.1039/c4sm00211c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Optical polarimetry measurements of the orientational order of a discotic liquid crystal based on a pyrene derivative confined in parallelly aligned nanochannels of monolithic, mesoporous alumina, silica, and silicon as a function of temperature, channel radius (3-22 nm) and surface chemistry reveal a competition of radial and axial columnar orders. The evolution of the orientational order parameter of the confined systems is continuous, in contrast to the discontinuous transition in the bulk. For channel radii larger than 10 nm we suggest several, alternative defect structures, which are compatible both with the optical experiments on the collective molecular orientation presented here and with a translational, radial columnar order reported in previous diffraction studies. For smaller channel radii our observations can semi-quantitatively be described by a Landau-de Gennes model with a nematic shell of radially ordered columns (affected by elastic splay deformations) that coexists with an orientationally disordered, isotropic core. For these structures, the cylindrical phase boundaries are predicted to move from the channel walls to the channel centres upon cooling, and vice-versa upon heating, in accord with the pronounced cooling/heating hystereses observed and the scaling behavior of the transition temperatures with the channel diameter. The absence of experimental hints of a paranematic state is consistent with a biquadratic coupling of the splay deformations to the order parameter.
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Affiliation(s)
- Andriy V Kityk
- Materials Physics and Technology, Hamburg University of Technology (TUHH), D-21073 Hamburg, Germany.
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33
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Zhang R, Zeng X, Prehm M, Liu F, Grimm S, Geuss M, Steinhart M, Tschierske C, Ungar G. Honeycombs in honeycombs: complex liquid crystal alumina composite mesostructures. ACS NANO 2014; 8:4500-4509. [PMID: 24758721 DOI: 10.1021/nn406368e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) were used to study orientation patterns of two polyphilic liquid crystals (LC) confined to cylindrical pores of anodic aluminum oxide (AAO). The hierarchical hybrid systems had the LC honeycomb (lattice parameter 3.5-4 nm) inside the pores of the AAO honeycomb (diameters 60 and 400 nm). By conducting complete reciprocal space mapping using SAXS, we conclude that the columns of both compounds align in planes normal to the AAO pore axis, with a specific crystallographic direction of the LC lattice aligning strictly parallel to the pore axis. AFM of LC-containing AAO fracture surfaces further revealed that the columns of the planar anchoring LC (compound 1) formed concentric circles in the plane normal to the pore axis near the AAO wall. Toward the pore center, the circles become anisometric "racetrack" loops consisting of two straight segments and two semicircles. This mode compensates for slight ellipticity of the pore cross section. Indications are, however, that for perfectly circular pores, circular shape is maintained right to the center of the pore, the radius coming down to the size of a molecule. For the homeotropically anchoring compound 2, the columns are to the most part straight and parallel to each other, arranged in layers normal to the AAO pore axis, like logs in an ordered pile. Only near the pore wall the columns splay somewhat. In both cases, columns are confined to layers strictly perpendicular to the AAO pore axis, and there is no sign of escape to the third dimension or of axial orientation, the latter having been reported previously for some discotic LCs. The main cause of the two new LC configurations, the "racetrack" and the "logpile", and of their difference from those of confined nematic LC, is the very high splay energy and low bend energy of columnar phases.
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Affiliation(s)
- Ruibin Zhang
- Department of Materials Science and Engineering, University of Sheffield , Sheffield S1 3JD, United Kingdom
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34
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Krause C, Zorn R, Frick B, Schönhals A. Thermal properties and vibrational density of states of a nanoconfined discotic liquid crystal. Colloid Polym Sci 2014. [DOI: 10.1007/s00396-014-3247-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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35
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Switchable dielectric permittivity with temperature and Dc-bias in a semifluorinated azobenzene derivative. Colloid Polym Sci 2014. [DOI: 10.1007/s00396-014-3217-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Suzuki Y, Duran H, Steinhart M, Butt HJ, Floudas G. Suppression of Poly(ethylene oxide) Crystallization in Diblock Copolymers of Poly(ethylene oxide)-b-poly(ε-caprolactone) Confined to Nanoporous Alumina. Macromolecules 2014. [DOI: 10.1021/ma4026477] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yasuhito Suzuki
- Max-Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Hatice Duran
- Department of Materials Science & Nanotechnology Engineering, TOBB University of Economics and Technology, 06560 Ankara, Turkey
| | - Martin Steinhart
- Institut
für Chemie neuer Materialien, Universität Osnabrück, D-49069 Osnabrück, Germany
| | | | - George Floudas
- Department
of Physics, University of Ioannina, 45110 Ioannina, Greece
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37
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Grigoriadis C, Niebel C, Ruzié C, Geerts YH, Floudas G. Order, Viscoelastic, and Dielectric Properties of Symmetric and Asymmetric Alkyl[1]benzothieno[3,2-b][1]benzothiophenes. J Phys Chem B 2014; 118:1443-51. [DOI: 10.1021/jp412422e] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
| | - Claude Niebel
- Laboratoire de Chimie des Polymères CP 206/01,
Faculté des Sciences, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - Christian Ruzié
- Laboratoire de Chimie des Polymères CP 206/01,
Faculté des Sciences, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - Yves H. Geerts
- Laboratoire de Chimie des Polymères CP 206/01,
Faculté des Sciences, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - George Floudas
- Department of Physics, University of Ioannina, 45110 Ioannina, Greece
- Max-Planck
Institute for Polymer Research, Mainz, Germany
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Smith BD, Kirby DJ, Rivera IO, Keating CD. Self-assembly of segmented anisotropic particles: tuning compositional anisotropy to form vertical or horizontal arrays. ACS NANO 2013; 7:825-833. [PMID: 23244212 DOI: 10.1021/nn305394s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Columnar arrays of anisotropic nano- and microparticles, in which the long axes of the particles are oriented perpendicular to the substrate, are of interest for photovoltaics and other applications. Array assembly typically requires applied electric or magnetic fields and/or controlled drying, which are challenging over large areas. Here, we describe a scalable approach to self-assemble multicomponent nanowires into columnar arrays. Self-assembly of partially etched nanowires (PENs) occurred spontaneously during sedimentation from suspension, without drying or applied fields. PENs, which have segments that are either gold or "empty" (solvent-filled) surrounded by a silica shell, were produced from striped metal nanowires by first coating with silica and then removing sacrificial segments by acid etching. Electrostatic repulsion between the particles was necessary for array assembly; however, details of PEN surface chemistry were relatively unimportant. The aspect ratio and relative center of mass (COM) of the PENs were important for determining whether the PEN long axes were vertically or horizontally aligned with respect to the underlying substrate. Arrays with predominantly vertically aligned particles were achieved for PENs with a large offset in COM relative to the geometric center, while other types of PENs formed horizontal arrays. Assemblies were formed over >10 cm(2) areas, with over 60% of particles standing. We assessed array uniformity and reproducibility by imaging many positions within each sample and performing multiple assemblies of differently segmented PENs. This work demonstrates the versatility of gravity-driven PEN array assembly and provides a framework for designing other anisotropic particle systems that self-assemble into columnar arrays.
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Affiliation(s)
- Benjamin D Smith
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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