1
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Rams-Baron M, Błażytko A, Casalini R, Paluch M. Insight into properties of sizable glass former from volumetric measurements. J Chem Phys 2024; 161:064502. [PMID: 39120034 DOI: 10.1063/5.0217660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 07/11/2024] [Indexed: 08/10/2024] Open
Abstract
Sizable glass formers feature numerous unique properties and potential applications, but many questions regarding their glass transition dynamics have not been resolved yet. Here, we have analyzed structural relaxation times measured as a function of temperature and pressure in combination with the equation of state obtained from pressure-volume-temperature measurements. Despite evidence from previous dielectric studies indicating a remarkable sensitivity of supercooled dynamics to compression, and contrary to intuition, our results demonstrated the proof for the almost equivalent importance of thermal energy and free volume fluctuations in controlling reorientation dynamics of sizable molecules. The found scaling exponent γ = 3.0 and Ev/Ep ratio of 0.6 were typical for glass-forming materials with relaxation dynamics determined by both effects with a minor advantage of thermal fluctuations involvement. It shows that the high values of key parameters characterizing the sensitivity of the glass transition dynamics to pressure changes, i.e., activation volume ΔV and dTg/dP, are not a valid premise for a remarkable contribution of volume to glass transition dynamics.
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Affiliation(s)
- Marzena Rams-Baron
- August Chełkowski Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Alfred Błażytko
- August Chełkowski Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Riccardo Casalini
- Chemistry Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, USA
| | - Marian Paluch
- August Chełkowski Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
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2
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Koymeth S, Yao B, Paluch M, Dulski M, Swadzba-Kwasny M, Wojnarowska Z. Inflection Point in Pressure Dependence of Ionic Conductivity as a Fingerprint of Local Structure Formation. J Phys Chem B 2024; 128:5109-5117. [PMID: 38718191 PMCID: PMC11129299 DOI: 10.1021/acs.jpcb.3c08506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 04/05/2024] [Accepted: 04/15/2024] [Indexed: 05/24/2024]
Abstract
In this study, we employed dielectric spectroscopy to investigate the effect of temperature and pressure on the ion dynamics of phosphonium ionic liquids (ILs) differing by the length of an alkyl chain, [P666,n][TFSI] (n = 2, 6, 8, 12). We found that both temperature and pressure dependence of dc-conductivity (σdc) determined for all examined ILs herein exhibit unique characteristics, unusual for aprotic ILs. Two regions differing by ion self-organization have been identified from the derivative analysis of σdc(T-1) data. On the other hand, isothermal measurements performed at elevated pressure revealed a unique concave-convex character of σdc(P) dependences, resulting in a clear minimum in the pressure behavior of activation volume. Such an inflection point characterizing the pressure dependence of σdc in [P666,n][TFSI] ILs can be considered an inherent feature of ion dynamics governed by structural self-assembly. Our results offer a unique perspective to link the ion mobility at various T-P conditions to the nanostructural organization of ionic systems.
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Affiliation(s)
- S. Koymeth
- Faculty
of Science and Technology, Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1A, Chorzów 41-500, Poland
| | - B. Yao
- Faculty
of Science and Technology, Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1A, Chorzów 41-500, Poland
| | - M. Paluch
- Faculty
of Science and Technology, Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1A, Chorzów 41-500, Poland
| | - M. Dulski
- Faculty
of Science and Technology, Institute of Materials Science, University of Silesia in Katowice, 75 Pułku Piechoty 1A, Chorzów 41-500, Poland
| | - M. Swadzba-Kwasny
- The
QUILL Research Centre, School of Chemistry and Chemical Engineering, The Queen’s University of Belfast, David Keir Building, Stranmillis
Road, Belfast BT9 5AG, U.K.
| | - Z. Wojnarowska
- Faculty
of Science and Technology, Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1A, Chorzów 41-500, Poland
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3
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Yao B, Paluch M, Wojnarowska Z. Effect of bulky anions on the liquid-liquid phase transition in phosphonium ionic liquids: Ambient and high-pressure dielectric studies. Sci Rep 2023; 13:3040. [PMID: 36810358 PMCID: PMC9944924 DOI: 10.1038/s41598-023-29518-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 02/06/2023] [Indexed: 02/23/2023] Open
Abstract
Although the first-order liquid-liquid phase transition (LLT) has been reported to exist in various systems (i.e., phosphorus, silicon, water, triphenyl phosphite, etc.), it is still one of the most challenging problems in the field of physical science. Recently, we found that this phenomenon occurs in the family of trihexyl(tetradecyl)phosphonium [P666,14]+ based ionic liquids (ILs) with different anions (Wojnarowska et al in Nat Commun 13:1342, 2022). To understand the molecular structure-property relationships governing LLT, herein, we examine ion dynamics of two other quaternary phosphonium ILs containing long alkyl chains in cation and anion. We found that IL with the anion containing branched -O-(CH2)5-CH3 side chains does not reveal any signs of LLT, while IL with shorter alkyl chains in the anion brings a hidden LLT, i.e., it overlaps with the liquid-glass transition. Ambient pressure dielectric and viscosity measurements revealed a peculiar behavior of ion dynamics near Tg for IL with hidden LLT. Moreover, high-pressure studies have shown that IL with hidden LLT has relatively strong pressure sensitivity compared to the one without first-order phase transition. At the same time, the former exposes the inflection point indicating the concave-convex character of logτσ(P) dependences.
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Affiliation(s)
- B. Yao
- grid.11866.380000 0001 2259 4135Institute of Physics, University of Silesia, SMCEBI, 75 Pulku Piechoty 1A, 41-500 Chorzow, Poland
| | - M. Paluch
- grid.11866.380000 0001 2259 4135Institute of Physics, University of Silesia, SMCEBI, 75 Pulku Piechoty 1A, 41-500 Chorzow, Poland
| | - Z. Wojnarowska
- grid.11866.380000 0001 2259 4135Institute of Physics, University of Silesia, SMCEBI, 75 Pulku Piechoty 1A, 41-500 Chorzow, Poland
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4
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Grzybowski A, Lowe AR, Jasiok B, Chorążewski M. Volumetric and viscosity data of selected oils analyzed in the density scaling regime. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118728] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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5
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Fractional Walden rule for aprotic ionic liquids: Experimental verification over a wide range of temperatures and pressures. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115772] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Philippi F, Welton T. Targeted modifications in ionic liquids - from understanding to design. Phys Chem Chem Phys 2021; 23:6993-7021. [PMID: 33876073 DOI: 10.1039/d1cp00216c] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ionic liquids are extremely versatile and continue to find new applications in academia as well as industry. This versatility is rooted in the manifold of possible ion types, ion combinations, and ion variations. However, to fully exploit this versatility, it is imperative to understand how the properties of ionic liquids arise from their constituents. In this work, we discuss targeted modifications as a powerful tool to provide understanding and to enable design. A 'targeted modification' is a deliberate change in the structure of an ionic liquid. This includes chemical changes in an experiment as well as changes to the parameterisation in a computer simulation. In any case, such a change must be purposeful to isolate what is of interest, studying, as far as is possible, only one concept at a time. The concepts can then be used as design elements. However, it is often found that several design elements interact with each other - sometimes synergistically, and other times antagonistically. Targeted modifications are a systematic way of navigating these overlaps. We hope this paper shows that understanding ionic liquids requires experimentalists and theoreticians to join forces and provides a tool to tackle the difficult transition from understanding to design.
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Affiliation(s)
- Frederik Philippi
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
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7
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Ransom TC, Casalini R, Fragiadakis D, Roland CM. The complex behavior of the “simplest” liquid: Breakdown of density scaling in tetramethyl tetraphenyl trisiloxane. J Chem Phys 2019; 151:174501. [DOI: 10.1063/1.5121021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- T. C. Ransom
- Naval Research Laboratory, Chemistry Division, Code 6100, Washington, DC 20375-5342, USA
| | - R. Casalini
- Naval Research Laboratory, Chemistry Division, Code 6100, Washington, DC 20375-5342, USA
| | - D. Fragiadakis
- Naval Research Laboratory, Chemistry Division, Code 6100, Washington, DC 20375-5342, USA
| | - C. M. Roland
- Naval Research Laboratory, Chemistry Division, Code 6100, Washington, DC 20375-5342, USA
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8
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Bonetti M, Dubois A. Isochronal superpositioning in the equilibrium regime of superpressed propylene carbonate to ∼ 1.8 GPa: A study by diffusivity measurement of the fluorescent probe Coumarin 1. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:97. [PMID: 31375947 DOI: 10.1140/epje/i2019-11861-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 06/28/2019] [Indexed: 06/10/2023]
Abstract
We address the problem of glass-forming of liquids by superpressing. We study the pressure-induced dynamic change of the fragile van der Waals liquid propylene carbonate towards the glassy state in the equilibrium regime by measuring the diffusivity of the fluorescent probe Coumarin 1 embedded in the host liquid. The probe diffusivity is measured by the fluorescence recovery after photobleaching (FRAP) technique across a bleached volume generated by the near-field diffracted pattern of a laser beam. The recovered fluorescence intensity fits to a stretched exponential with the diffusive time [Formula: see text] and the stretched exponent [Formula: see text] as free parameters. In the pressure range [0.3-1.0]GPa the diffusivity decouples from the Stokes-Einstein relation. The decoupling correlates well to a decrease of [Formula: see text]. The variation of [Formula: see text] is non-monotonous with [Formula: see text] showing a minimum at [Formula: see text] s. We evidence an isochronal superpositioning over about 3 decades of [Formula: see text] between ∼ 10 s and [Formula: see text] s and a density scaling in the whole investigated pressure range. The pressure at which [Formula: see text] is minimum coincides to the dynamical crossover pressure measured by other authors. This crossover pressure is compatible with the critical point of MCT theory. As our studied pressure range encompasses the critical pressure, the non-monotonous variation of [Formula: see text] opens new insight in the approach to the critical point.
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Affiliation(s)
- Marco Bonetti
- Service de Physique de l'Etat Condensé CEA-SPEC, CNRS, Université Paris-Saclay, CEA Saclay, F-91191, Gif sur Yvette, France.
| | - Alizée Dubois
- Service de Physique de l'Etat Condensé CEA-SPEC, CNRS, Université Paris-Saclay, CEA Saclay, F-91191, Gif sur Yvette, France
- Laboratoire de Physique, ENS de Lyon, F-69342, Lyon, France
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9
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Thoms E, Kołodziej S, Wikarek M, Klotz S, Pawlus S, Paluch M. Inflection point in the Debye relaxation time of 2-butyl-1-octanol. J Chem Phys 2018; 149:214502. [PMID: 30525728 DOI: 10.1063/1.5064757] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We report a striking anomaly in the pressure dependent Debye-relaxation time of the branched monohydroxy alcohol 2-butyl-1-octanol. Evidence of a crossover from slower to faster than exponential pressure dependency was obtained at different temperatures via high pressure broadband dielectric spectroscopy. At the same time, viscosity measurements reveal similar behavior in the viscosity, respectively, the structural relaxation time, indicating a similar origin of the phenomena.
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Affiliation(s)
- Erik Thoms
- Institute of Physics, University of Silesia, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Sławomir Kołodziej
- Institute of Physics, University of Silesia, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Michał Wikarek
- Institute of Physics, University of Silesia, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Stefan Klotz
- IMPMC, UMR 7590, Sorbonne Université, 4 Place Jussieu, 75252 Paris, France
| | - Sebastian Pawlus
- Institute of Physics, University of Silesia, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Marian Paluch
- Institute of Physics, University of Silesia, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
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10
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Casalini R, Roland CM. Nonlinear dielectric spectroscopy of propylene carbonate derivatives. J Chem Phys 2018; 148:134506. [DOI: 10.1063/1.5024379] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- R. Casalini
- Naval Research Laboratory, Chemistry Division, Washington, DC 20375-5342, USA
| | - C. M. Roland
- Naval Research Laboratory, Chemistry Division, Washington, DC 20375-5342, USA
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11
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Thoms E, Grzybowski A, Pawlus S, Paluch M. Breakdown of the Simple Arrhenius Law in the Normal Liquid State. J Phys Chem Lett 2018; 9:1783-1787. [PMID: 29578711 DOI: 10.1021/acs.jpclett.8b00583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
It is common practice to discuss the temperature effect on molecular dynamics of glass formers above the melting temperature in terms of the Arrhenius law. Using dielectric spectroscopy measurements of dc conductivity and structural relaxation time on the example of the typical glass former propylene carbonate, we provide experimental evidence that this practice is not justified. Our conclusions are supported by employing thermodynamic density scaling and the occurrence of inflection points in isothermal dynamic data measured at elevated pressure. Additionally, we propose a more suitable approach to describe the dynamics both above and below the inflection point based on a modified MYEGA model.
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Affiliation(s)
- Erik Thoms
- Institute of Physics, University of Silesia in Katowice , ul. 75 Pulku Piechoty 1 , 41-500 Chorzow , Poland
- Silesian Center for Education and Interdisciplinary Research , 75 Pulku Piechoty 1A , 41-500 Chorzow , Poland
| | - Andrzej Grzybowski
- Institute of Physics, University of Silesia in Katowice , ul. 75 Pulku Piechoty 1 , 41-500 Chorzow , Poland
- Silesian Center for Education and Interdisciplinary Research , 75 Pulku Piechoty 1A , 41-500 Chorzow , Poland
| | - Sebastian Pawlus
- Institute of Physics, University of Silesia in Katowice , ul. 75 Pulku Piechoty 1 , 41-500 Chorzow , Poland
- Silesian Center for Education and Interdisciplinary Research , 75 Pulku Piechoty 1A , 41-500 Chorzow , Poland
| | - Marian Paluch
- Institute of Physics, University of Silesia in Katowice , ul. 75 Pulku Piechoty 1 , 41-500 Chorzow , Poland
- Silesian Center for Education and Interdisciplinary Research , 75 Pulku Piechoty 1A , 41-500 Chorzow , Poland
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12
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Thoms E, Wojnarowska Z, Goodrich P, Jacquemin J, Paluch M. Communication: Inflection in the pressure dependent conductivity of the protic ionic liquid C8HIM NTf2. J Chem Phys 2017. [DOI: 10.1063/1.4982941] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Lyapin AG, Gromnitskaya E, Danilov IV, Brazhkin VV. Elastic properties of the hydrogen-bonded liquid and glassy glycerol under high pressure: comparison with propylene carbonate. RSC Adv 2017. [DOI: 10.1039/c7ra06165j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We compare elastic properties of the liquid and glassy glycerol and propylene carbonate as the archetypal molecular glass formers with and without hydrogen bonding.
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Affiliation(s)
- A. G. Lyapin
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
- Moscow Institute of Physics and Technology
| | - E. L. Gromnitskaya
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
| | - I. V. Danilov
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
- Moscow Institute of Physics and Technology
| | - V. V. Brazhkin
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
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14
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15
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Bonetti M. Pressure-Induced Glass Transition Probed via the Mobility of Coumarin 1 Fluorescent Molecule. J Phys Chem B 2016; 120:4319-28. [PMID: 27110923 DOI: 10.1021/acs.jpcb.6b02004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The route to form a glass is generally achieved upon cooling where the slowing down might be interpreted as the trapping of molecules in potential wells. On the other hand, isothermal compression induces a glassy state by modifying the molecular packing ending in jamming. Here, we focus on how isothermal compression perturbs the mobility of a probe molecule in three different host liquids up to the pressure-induced glass transition. By use of the fluorescence recovery technique, the diffusion of the fluorescent molecule Coumarin 1 (C1) is measured in poly(propylene glycol) (PPG-1000M and -2700M), in the fragile van der Waals propylene carbonate (PC), and in hydrogen-bonded methanol and ethanol. High pressures up to 6 GPa are obtained with a diamond anvil cell. In PC at a pressure ∼1.3 GPa close to the glass-transition pressure, the diffusion coefficient of C1 follows an Arrhenius behavior with an ∼5 orders of magnitude increase of the diffusive time. No decoupling from the Stokes-Einstein equation is noticed. A similar exponential behavior is measured in ethanol and methanol but extended to different pressure ranges up to 2.5 and 6.2 GPa, respectively. In PPG-1000M a decoupling from the Stokes-Einstein relation is observed between 0.3 and 0.8 GPa that could be related to a modification of the interaction between polymer segments and the probe molecule. These results might indicate that interaction between probe and dynamic heterogeneities become less important under applied pressure, unlike in the temperature-induced glass transition.
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Affiliation(s)
- Marco Bonetti
- SPEC, CEA, CNRS, Université Paris-Saclay , CEA Saclay, 91191 Gif sur Yvette, France
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16
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Srinivasan S. A Generalized Darcy–Dupuit–Forchheimer Model with Pressure-Dependent Drag Coefficient for Flow Through Porous Media Under Large Pressure Gradients. Transp Porous Media 2016. [DOI: 10.1007/s11242-016-0625-y] [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]
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17
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Casalini R, Fragiadakis D, Roland CM. Dynamic correlation length scales under isochronal conditions. J Chem Phys 2015; 142:064504. [DOI: 10.1063/1.4907371] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- R. Casalini
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington DC 20375-5342, USA
| | - D. Fragiadakis
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington DC 20375-5342, USA
| | - C. M. Roland
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington DC 20375-5342, USA
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18
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Pieprzyk S, Heyes DM, Brańka AC. Thermodynamic properties and entropy scaling law for diffusivity in soft spheres. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:012106. [PMID: 25122250 DOI: 10.1103/physreve.90.012106] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Indexed: 06/03/2023]
Abstract
The purely repulsive soft-sphere system, where the interaction potential is inversely proportional to the pair separation raised to the power n, is considered. The Laplace transform technique is used to derive its thermodynamic properties in terms of the potential energy and its density derivative obtained from molecular dynamics simulations. The derived expressions provide an analytic framework with which to explore soft-sphere thermodynamics across the whole softness-density fluid domain. The trends in the isochoric and isobaric heat capacity, thermal expansion coefficient, isothermal and adiabatic bulk moduli, Grüneisen parameter, isothermal pressure, and the Joule-Thomson coefficient as a function of fluid density and potential softness are described using these formulas supplemented by the simulation-derived equation of state. At low densities a minimum in the isobaric heat capacity with density is found, which is a new feature for a purely repulsive pair interaction. The hard-sphere and n = 3 limits are obtained, and the low density limit specified analytically for any n is discussed. The softness dependence of calculated quantities indicates freezing criteria based on features of the radial distribution function or derived functions of it are not expected to be universal. A new and accurate formula linking the self-diffusion coefficient to the excess entropy for the entire fluid softness-density domain is proposed, which incorporates the kinetic theory solution for the low density limit and an entropy-dependent function in an exponential form. The thermodynamic properties (or their derivatives), structural quantities, and diffusion coefficient indicate that three regions specified by a convex, concave, and intermediate density dependence can be expected as a function of n, with a narrow transition region within the range 5 < n < 8.
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Affiliation(s)
- S Pieprzyk
- Institute of Molecular Physics, Polish Academy of Sciences, Mariana Smoluchowskiego 17, 60-179 Poznań, Poland
| | - D M Heyes
- Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - A C Brańka
- Institute of Molecular Physics, Polish Academy of Sciences, Mariana Smoluchowskiego 17, 60-179 Poznań, Poland
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19
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Casalini R. The fragility of liquids and colloids and its relation to the softness of the potential. J Chem Phys 2013. [PMID: 23206028 DOI: 10.1063/1.4768267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A parameter that is often used to characterize the dynamics of supercooled liquids is the dynamic fragility, however it is still debated how the fragility is related to other physical properties. Recent experimental data on colloidal systems have found that fragility decreases with increasing softness of the intermolecular potential. This result is in apparent disagreement with recent molecular dynamics simulations reporting the opposite behavior. Herein, using the thermodynamical scaling exponent γ as a measure of the steepness of the potential we show how these different results can be reconciled and also agree with previous results obtained for the dynamics of supercooled liquids at high pressures.
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Affiliation(s)
- R Casalini
- Chemistry Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375-5342, USA
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20
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Pawlus S, Klotz S, Paluch M. Effect of compression on the relationship between viscosity and dielectric relaxation time in hydrogen-bonded primary alcohols. PHYSICAL REVIEW LETTERS 2013; 110:173004. [PMID: 23679720 DOI: 10.1103/physrevlett.110.173004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Indexed: 06/02/2023]
Abstract
High pressure viscosity and dielectric measurements were carried out on two monohydroxy alcohols, 2-ethyl-1-hexanol and 5-methyl-2-hexanol, at room temperature. Analysis of the dielectric relaxation times versus viscosity revealed the breakdown of the Einstein-Debye relation above some characteristic pressure. The failure of the Einstein-Debye relation is a manifestation of pressure induced changes of supramolecular hydrogen bonded structures which occur in these liquids.
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Affiliation(s)
- S Pawlus
- Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
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21
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Kondrin MV, Gromnitskaya EL, Pronin AA, Lyapin AG, Brazhkin VV, Volkov AA. Dielectric spectroscopy and ultrasonic study of propylene carbonate under ultra-high pressures. J Chem Phys 2012; 137:084502. [DOI: 10.1063/1.4746022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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22
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López ER, Pensado AS, Fernández J, Harris KR. On the density scaling of pVT data and transport properties for molecular and ionic liquids. J Chem Phys 2012; 136:214502. [DOI: 10.1063/1.4720070] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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23
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Harris KR, Kanakubo M. High pressure studies of the transport properties of ionic liquids. Faraday Discuss 2012; 154:425-38; discussion 439-64, 465-71. [DOI: 10.1039/c1fd00085c] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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24
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Papathanassiou AN, Sakellis I, Grammatikakis J, Roland CM. The role of the isothermal bulk modulus in the molecular dynamics of super-cooled liquids. J Chem Phys 2011; 135:244508. [PMID: 22225170 DOI: 10.1063/1.3666008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Elastic models imply that the energy expended for a flow event in ultra-viscous matter coincides with the elastic work required for deforming and re-arranging the environment of the moving entity. This is quite promising for explaining the strong non-Arrhenius behavior of dynamic quantities of fragile super-cooled liquids. We argue that the activation volume obtained from dielectric relaxation and light-scattering experiments for super-cooled liquids should scale with the Gibbs free energy of activation, with a proportionality constant determined by the isothermal bulk modulus and its pressure derivative, as described by an earlier thermodynamic elastic model. For certain super-cooled liquids the bulk compression transpiring in the local environment, as governed by the isothermal bulk modulus, play a significant role in the reorientational dynamics, with far-field density fluctuations and volume changes avoided by shear deformation.
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