1
|
Dyre JC. Solid-that-Flows Picture of Glass-Forming Liquids. J Phys Chem Lett 2024; 15:1603-1617. [PMID: 38306474 PMCID: PMC10875679 DOI: 10.1021/acs.jpclett.3c03308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/12/2024] [Accepted: 01/17/2024] [Indexed: 02/04/2024]
Abstract
This perspective article reviews arguments that glass-forming liquids are different from those of standard liquid-state theory, which typically have a viscosity in the mPa·s range and relaxation times on the order of picoseconds. These numbers grow dramatically and become 1012 - 1015 times larger for liquids cooled toward the glass transition. This translates into a qualitative difference, and below the "solidity length" which is roughly one micron at the glass transition, a glass-forming liquid behaves much like a solid. Recent numerical evidence for the solidity of ultraviscous liquids is reviewed, and experimental consequences are discussed in relation to dynamic heterogeneity, frequency-dependent linear-response functions, and the temperature dependence of the average relaxation time.
Collapse
Affiliation(s)
- Jeppe C Dyre
- "Glass and Time", IMFUFA, Dept. of Sciences, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| |
Collapse
|
2
|
Structure and dynamics of aromatic and alkyl substituted Imidazolium-based ionic liquids. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
3
|
Weigl P, Hecksher T, Dyre JC, Walther T, Blochowicz T. Identity of the local and macroscopic dynamic elastic responses in supercooled 1-propanol. Phys Chem Chem Phys 2021; 23:16537-16541. [PMID: 34312639 DOI: 10.1039/d1cp02671b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Glass-forming liquids are well known to have significant dynamic heterogeneities, leading to spatially grossly varying elastic properties throughout the system. In this paper, we compare the local elastic response of supercooled 1-propanol monitored by triplet state solvation dynamics to the macroscopic dynamic shear modulus measured by a piezo-electric gauge. The time-dependent responses are found to be identical, which means that the dynamic macroscopic shear modulus provides a good measure of the average local elastic properties. Since the macroscopic shear modulus of a dynamically inhomogeneous system in general is not just the average of the local moduli, there was no reason to expect such a result. This surprising finding not only provides constraints for models of dynamical heterogeneities in glass-forming liquids, but also allows for a fairly straightforward check on elastic models for glassy dynamics.
Collapse
Affiliation(s)
- Peter Weigl
- Institute for Condensed Matter Physics, Technical University of Darmstadt, 64289 Darmstadt, Germany.
| | | | | | | | | |
Collapse
|
4
|
Hodge SR, Corcelli SA, Berg MA. Nonlinear measurements of kinetics and generalized dynamical modes. II. Application to a simulation of solvation dynamics in an ionic liquid. J Chem Phys 2021; 155:024123. [PMID: 34266263 DOI: 10.1063/5.0053424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Solvation dynamics in ionic liquids show features that are often associated with supercooled liquids, including "stretched" nonexponential relaxation. To better understand the mechanism behind the stretching, the nonlinear mode-correlation methods proposed in Paper I [S. R. Hodge and M. A. Berg, J. Chem. Phys. 155, 024122 (2021)] are applied to a simulation of a prototypical ionic liquid. A full Green's function is recovered. In addition, specific tests for non-Gaussian dynamics are made. No deviations from Gaussian dynamics are found. This finding is incompatible with rate heterogeneity as a cause of the nonexponential relaxation and appears to be in conflict with an earlier multidimensional analysis of the same data. Although this conflict is not resolved here, this work does demonstrate the practicality of mode-correlation analysis in the face of finite datasets and calculations.
Collapse
Affiliation(s)
- Stuart R Hodge
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Steven A Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Mark A Berg
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| |
Collapse
|
5
|
Amith WD, Araque JC, Margulis CJ. Relationship between the Relaxation of Ionic Liquid Structural Motifs and That of the Shear Viscosity. J Phys Chem B 2021; 125:6264-6271. [PMID: 34097825 PMCID: PMC8279556 DOI: 10.1021/acs.jpcb.1c03105] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
In a set of recent
articles, we have highlighted that friction
is highly inhomogeneous in a typical ionic liquid (IL) with charge
networks that are stiff and charge-depleted regions that are soft.
This has consequences not only for the dynamics of ILs but also for the transport properties of solutes
dissolved in them. In this article, we explore whether the family
of alkylimidazolium ILs coupled with bis(trifluoromethylsulfonyl)imide
(with similar Coulombic interactions but different alkyl tails), when
dynamically “equalized” by having a similar shear viscosity,
display q-dependent structural relaxation time scales
that are the same across the family. Our results show that this is
not the case, and in fact, the relaxation of in-network charge alternation
appears to be significantly affected by the presence of separate polar
and apolar domains. However, we also find that if one was to assign
weight factors to the relaxation of the structural motifs, charge
alternation always contributes about the same amount (between 62.1
and 66.3%) across systems to the running integral of the stress tensor
correlation function from which the shear viscosity is derived. Adjacency
correlations between positive and negative moieties also contribute
an identical amount if a prepeak is not present (about 38%) and a
slightly smaller amount (about 28%) when intermediate range order
exists. The prepeak only contributes about 6% to viscoelastic relaxation,
highlighting that the dynamics of the smaller scale motifs is the
most important.
Collapse
Affiliation(s)
| | - Juan C Araque
- School of Engineering, Benedictine College, Atchison, Kansas 66002, United States
| | - Claudio J Margulis
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| |
Collapse
|
6
|
Leier J, Michenfelder NC, Unterreiner A. Understanding the Photoexcitation of Room Temperature Ionic Liquids. ChemistryOpen 2021; 10:72-82. [PMID: 33565733 PMCID: PMC7874249 DOI: 10.1002/open.202000278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/26/2020] [Indexed: 12/14/2022] Open
Abstract
Photoexcitation of (neat) room temperature ionic liquids (RTILs) leads to the observation of transient species that are reminiscent of the composition of the RTILs themselves. In this minireview, we summarize state-of-the-art in the understanding of the underlying elementary processes. By varying the anion or cation, one aim is to generally predict radiation-induced chemistry and physics of RTILs. One major task is to address the fate of excess electrons (and holes) after photoexcitation, which implies an overview of various formation mechanisms considering structural and dynamical aspects. Therefore, transient studies on time scales from femtoseconds to microseconds can greatly help to elucidate the most relevant steps after photoexcitation. Sometimes, radiation may eventually result in destruction of the RTILs making photostability another important issue to be discussed. Finally, characteristic heterogeneities can be associated with specific physicochemical properties. Influencing these properties by adding conventional solvents, like water, can open a wide field of application, which is briefly summarized.
Collapse
Affiliation(s)
- Julia Leier
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Nadine C. Michenfelder
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Andreas‐Neil Unterreiner
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| |
Collapse
|
7
|
Amith WD, Araque JC, Margulis CJ. A Pictorial View of Viscosity in Ionic Liquids and the Link to Nanostructural Heterogeneity. J Phys Chem Lett 2020; 11:2062-2066. [PMID: 32079397 DOI: 10.1021/acs.jpclett.0c00170] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Prototypical ionic liquids (ILs) are characterized by three structural motifs associated with (1) vicinal interactions, (2) the formation of positive-negative charge-alternating chains or networks, and (3) the alternation of these networks with apolar domains. In recent articles, we highlighted that the friction and mobility in these systems are nowhere close to being spatially homogeneous. This results in what one could call mechanical heterogeneity, where charge networks are intrinsically stiff and charge-depleted regions are softer, flexible, and mobile. This Letter attempts to provide a clear and visual connection between friction-associated with the dynamics of the structural motifs (in particular, the charge network)-and recent theoretical work by Yamaguchi linking the time-dependent viscosity of ILs to the decay of the charge alternation peak in the dynamic structure function. We propose that charge blurring associated with the loss of memory of where positive and negative charges are within networks is the key mechanism associated with viscosity in ILs. An IL will have low viscosity if a characteristic charge-blurring decorrelation time is low. With this in mind, engineering new low-viscosity ILs is reduced to understanding how to minimize this quantity.
Collapse
Affiliation(s)
| | - Juan C Araque
- School of Engineering, Benedictine College, Atchison, Kansas 66002, United States
| | - Claudio J Margulis
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| |
Collapse
|
8
|
Bernardino K, Goloviznina K, Gomes MC, Pádua AAH, Ribeiro MCC. Ion pair free energy surface as a probe of ionic liquid structure. J Chem Phys 2020; 152:014103. [DOI: 10.1063/1.5128693] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- Kalil Bernardino
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil
| | - Kateryna Goloviznina
- Laboratoire de Chimie, ENS de Lyon, Université de Lyon, CNRS, 69364 Lyon, France
| | | | - Agílio A. H. Pádua
- Laboratoire de Chimie, ENS de Lyon, Université de Lyon, CNRS, 69364 Lyon, France
| | - Mauro C. C. Ribeiro
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil
| |
Collapse
|
9
|
Nakamura I, Shock CJ, Eggart L, Gao T. Theoretical Aspects of Ionic Liquids for Soft‐Matter Sciences. Isr J Chem 2018. [DOI: 10.1002/ijch.201800143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Issei Nakamura
- Department of PhysicsMichigan Technological University Houghton MI 49931 USA
| | - Cameron J. Shock
- Department of PhysicsMichigan Technological University Houghton MI 49931 USA
| | - Lisa Eggart
- Department of PhysicsMichigan Technological University Houghton MI 49931 USA
| | - Tong Gao
- Department of PhysicsMichigan Technological University Houghton MI 49931 USA
| |
Collapse
|
10
|
Araque JC, Margulis CJ. In an ionic liquid, high local friction is determined by the proximity to the charge network. J Chem Phys 2018; 149:144503. [PMID: 30316258 DOI: 10.1063/1.5045675] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Structural heterogeneity in Ionic Liquids (ILs) is to a large extent defined by nanoscale apolar pockets that act as spacers between strings of positive and negative charges that alternate. In contrast to this, recent work from our group and that of others appear to indicate that dynamic, energetic, and mechanical heterogeneities are governed by the charged part of the liquid. In this article, we study the dynamics of methane, a small apolar solute, in the family of ILs 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ( Im 1 , n + /NTf2 -), with n = 2, 4, 8 at temperatures that make the viscosity for each liquid similar and around 8 cP. We do this in an attempt to equalize the effect of the solvent on the dynamics of the solute. In all cases, we find that solute proximity to charge-enhanced regions coincides with translationally caged regimes (high local friction) whereas the opposite is true in charge-depleted regions. In a way, these ILs behave like a liquid within a liquid where the charge network is the high friction component.
Collapse
Affiliation(s)
- Juan C Araque
- School of Engineering, Benedictine College, Atchison, Kansas 66002, USA
| | | |
Collapse
|
11
|
Perkin S, Kirchner B, Fayer MD. Preface: Special Topic on Chemical Physics of Ionic Liquids. J Chem Phys 2018; 148:193501. [DOI: 10.1063/1.5039492] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Susan Perkin
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, D-53115 Bonn, Germany
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| |
Collapse
|