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Cywiak D, Gil-Villegas A, Patti A. Long-time relaxation dynamics in nematic and smectic liquid crystals of soft repulsive colloidal rods. Phys Rev E 2022; 105:014703. [PMID: 35193200 DOI: 10.1103/physreve.105.014703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 01/04/2022] [Indexed: 06/14/2023]
Abstract
Understanding the relaxation dynamics of colloidal suspensions is crucial to identifying the elements that influence the mobility of their constituents, assessing their macroscopic response across the relevant time and length scales, and thus disclosing the fundamentals underpinning their exploitation in formulation engineering. In this work, we specifically assess the impact of long-ranged ordering on the relaxation dynamics of suspensions of soft repulsive rodlike particles, which are able to self-organize into nematic and smectic liquid-crystalline phases. Rods are modeled as soft repulsive spherocylinders with a length-to-diameter ratio L^{★}=5, interacting via the truncated and shifted Kihara potential. By performing dynamic Monte Carlo simulations, we analyze the effect of translational and orientational order on the diffusion of the rods along the relevant directions imposed by the morphology of the background phases. To provide a clear picture of the resulting dynamics, we assess its dependence on temperature, which can dramatically determine the response time of the system relaxation and the self-diffusion coefficients of the rods. The computation of the van Hove correlation functions allows us to identify the existence of rods that diffuse significantly faster than the average and whose concentration can be accurately adjusted by a suitable choice of temperature.
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Affiliation(s)
- Daniela Cywiak
- División de Ciencias e Ingenierías, Universidad de Guanajuato, Campus León, Mexico
| | | | - Alessandro Patti
- Department of Chemical Engineering and Analytical Science, University of Manchester, Manchester M13 9PL, United Kingdom
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2
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Zhao Y, Stratt RM. Measuring order in disordered systems and disorder in ordered systems: Random matrix theory for isotropic and nematic liquid crystals and its perspective on pseudo-nematic domains. J Chem Phys 2018; 148:204501. [PMID: 29865812 DOI: 10.1063/1.5024678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Surprisingly long-ranged intermolecular correlations begin to appear in isotropic (orientationally disordered) phases of liquid crystal forming molecules when the temperature or density starts to close in on the boundary with the nematic (ordered) phase. Indeed, the presence of slowly relaxing, strongly orientationally correlated, sets of molecules under putatively disordered conditions ("pseudo-nematic domains") has been apparent for some time from light-scattering and optical-Kerr experiments. Still, a fully microscopic characterization of these domains has been lacking. We illustrate in this paper how pseudo-nematic domains can be studied in even relatively small computer simulations by looking for order-parameter tensor fluctuations much larger than one would expect from random matrix theory. To develop this idea, we show that random matrix theory offers an exact description of how the probability distribution for liquid-crystal order parameter tensors converges to its macroscopic-system limit. We then illustrate how domain properties can be inferred from finite-size-induced deviations from these random matrix predictions. A straightforward generalization of time-independent random matrix theory also allows us to prove that the analogous random matrix predictions for the time dependence of the order-parameter tensor are similarly exact in the macroscopic limit, and that relaxation behavior of the domains can be seen in the breakdown of the finite-size scaling required by that random-matrix theory.
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Affiliation(s)
- Yan Zhao
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Richard M Stratt
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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3
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Thomaz JE, Bailey HE, Fayer MD. The influence of mesoscopic confinement on the dynamics of imidazolium-based room temperature ionic liquids in polyether sulfone membranes. J Chem Phys 2017; 147:194502. [DOI: 10.1063/1.5003036] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Joseph E. Thomaz
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Heather E. Bailey
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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4
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Bailey HE, Wang YL, Fayer MD. Impact of Hydrogen Bonding on the Dynamics and Structure of Protic Ionic Liquid/Water Binary Mixtures. J Phys Chem B 2017; 121:8564-8576. [DOI: 10.1021/acs.jpcb.7b06376] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Heather E. Bailey
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Yong-Lei Wang
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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5
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Frechette L, Stratt RM. The inherent dynamics of isotropic- and nematic-phase liquid crystals. J Chem Phys 2017; 144:234505. [PMID: 27334177 DOI: 10.1063/1.4953618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The geodesic (shortest) pathways through the potential energy landscape of a liquid can be thought of as defining what its dynamics would be if thermal noise were removed, revealing what we have called the "inherent dynamics" of the liquid. We show how these inherent paths can be located for a model liquid crystal former, showing, in the process, how the molecular mechanisms of translation and reorientation compare in the isotropic and nematic phases of these systems. These mechanisms turn out to favor the preservation of local orientational order even under macroscopically isotropic conditions (a finding consistent with the experimental observation of pseudonematic domains in these cases), but disfavor the maintenance of macroscopic orientational order, even in the nematic phase. While the most efficient nematic pathways that maintain nematic order are indeed shorter than those that do not, it is apparently difficult for the system to locate these paths, suggesting that molecular motion in liquid-crystal formers is dynamically frustrated, and reinforcing the sense that there are strong analogies between liquid crystals and supercooled liquids.
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Affiliation(s)
- Layne Frechette
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Richard M Stratt
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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6
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Bender JS, Cohen SR, He X, Fourkas JT, Coasne B. Toward in Situ Measurement of the Density of Liquid Benzene Using Optical Kerr Effect Spectroscopy. J Phys Chem B 2016; 120:9103-14. [PMID: 27472265 DOI: 10.1021/acs.jpcb.6b06421] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | - Benoit Coasne
- Laboratoire
Interdisciplinaire de Physique (LIPhy), Université Grenoble Alpes and CNRS (UMR 5588), F-38000 Grenoble, France
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7
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Tamimi A, Bailey HE, Fayer MD. Alkyl Chain Length Dependence of the Dynamics and Structure in the Ionic Regions of Room-Temperature Ionic Liquids. J Phys Chem B 2016; 120:7488-501. [DOI: 10.1021/acs.jpcb.6b05397] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Amr Tamimi
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Heather E. Bailey
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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8
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Sokolowsky KP, Bailey HE, Hoffman DJ, Andersen HC, Fayer MD. Critical Slowing of Density Fluctuations Approaching the Isotropic–Nematic Transition in Liquid Crystals: 2D IR Measurements and Mode Coupling Theory. J Phys Chem B 2016; 120:7003-15. [DOI: 10.1021/acs.jpcb.6b04997] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Heather E. Bailey
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - David J. Hoffman
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Hans C. Andersen
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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9
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Sokolowsky KP, Bailey HE, Fayer MD. New divergent dynamics in the isotropic to nematic phase transition of liquid crystals measured with 2D IR vibrational echo spectroscopy. J Chem Phys 2014; 141:194502. [DOI: 10.1063/1.4901081] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
| | - Heather E. Bailey
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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Kel O, Tamimi A, Fayer MD. The Influence of Cholesterol on Fast Dynamics Inside of Vesicle and Planar Phospholipid Bilayers Measured with 2D IR Spectroscopy. J Phys Chem B 2014; 119:8852-62. [DOI: 10.1021/jp503940k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Oksana Kel
- Department
of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Amr Tamimi
- Department
of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305-5080, United States
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