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Sheydaafar Z, Dyre JC, Schrøder TB. Scaling Properties of Liquid Dynamics Predicted from a Single Configuration: Pseudoisomorphs for Harmonic-Bonded Molecules. J Phys Chem B 2024; 128:8054-8064. [PMID: 39110776 DOI: 10.1021/acs.jpcb.4c03982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Isomorphs are curves in the thermodynamic phase diagram of invariant excess entropy, structure, and dynamics, while pseudoisomorphs are curves of invariant structure and dynamics, but not of the excess entropy. The latter curves have been shown to exist in molecular models with flexible bonds [Olsen, A. E. J. Chem. Phys. 2016, 145, 241103]. We here present three force-based methods to trace out pseudoisomorphs based on a single configuration and test them on the asymmetric dumbbell and 10-bead Lennard-Jones chain models with bonds modeled as harmonic springs. The three methods are based on requiring that particle forces, center-of-mass forces, and torques, respectively, are invariant in reduced units. For each of the two investigated models we identify a method that works well for tracing out pseudoisomorphs, but these methods are not the same. Overall, we find that the more internal degrees of freedom there are in the molecule studied, the less they appear to affect the gross dynamical behavior. Moreover, the "internal" degrees of freedom (including rotation) do not significantly affect the scaling behavior of the dynamical/transport coefficients provided some 'quenching' is performed.
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Affiliation(s)
- Zahraa Sheydaafar
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Jeppe C Dyre
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Thomas B Schrøder
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
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Danilov I, Gromnitskaya E, Brazhkin V. Thermobaric history as a tool to govern properties of glasses: case of dipropylene glycol. Phys Chem Chem Phys 2023; 25:26813-26819. [PMID: 37782054 DOI: 10.1039/d3cp03306f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
The elastic properties of high- and low-pressure glasses of dipropylene glycol were determined for the first time under conditions of isothermal compression up to 1 GPa at 77 K and isobaric heating of 77-300 K at 0.05 GPa and 1 GPa. A strong dependence of the elastic properties of glasses on their thermobaric history has been revealed: glasses obtained at high pressure have not only higher densities (3.9%), but also noticeably higher elastic moduli. This effect is especially pronounced in the shear modulus: high-pressure glass has a 30% higher shear modulus than low-pressure glass. The behavior of elastic moduli during the glass-to-liquid transition also depends on the thermobaric history. Glass produced at low pressure but heated at high pressure has anomalous temperature dependences of the elastic moduli. Heating dipropylene glycol glasses at different pressures allowed us to refine the Tg(P) dependence.
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Affiliation(s)
- Igor Danilov
- Institute for High Pressure Physics, Russian Academy of Sciences, 14, Kaluzhskoe shosse, 108840, Troitsk, Moscow, Russia.
| | - Elena Gromnitskaya
- Institute for High Pressure Physics, Russian Academy of Sciences, 14, Kaluzhskoe shosse, 108840, Troitsk, Moscow, Russia.
| | - Vadim Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences, 14, Kaluzhskoe shosse, 108840, Troitsk, Moscow, Russia.
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Sheydaafar Z, Dyre JC, Schrøder TB. Scaling Properties of Liquid Dynamics Predicted from a Single Configuration: Small Rigid Molecules. J Phys Chem B 2023; 127:3478-3487. [PMID: 37040433 DOI: 10.1021/acs.jpcb.3c01574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Isomorphs are curves in the thermodynamic phase diagram along which structure and dynamics are invariant to a good approximation. There are two main ways to trace out isomorphs, the configurational-adiabat method and the direct-isomorph-check method. Recently a new method based on the scaling properties of forces was introduced and shown to work very well for atomic systems [T. B. Schrøder, Phys. Rev. Lett. 2022, 129, 245501]. A unique feature of this method is that it only requires a single equilibrium configuration for tracing out an isomorph. We here test generalizations of this method to molecular systems and compare to simulations of three simple molecular models: the asymmetric dumbbell model of two Lennard-Jones spheres, the symmetric inverse-power-law dumbbell model, and the Lewis-Wahnström o-terphenyl model. We introduce and test two force-based and one torque-based methods, all of which require just a single configuration for tracing out an isomorph. Overall, the method based on requiring invariant center-of-mass reduced forces works best.
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Affiliation(s)
- Zahraa Sheydaafar
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Jeppe C Dyre
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Thomas B Schrøder
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
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Koperwas K, Grzybowski A, Paluch M. Virial-potential-energy correlation and its relation to density scaling for quasireal model systems. Phys Rev E 2021; 102:062140. [PMID: 33466035 DOI: 10.1103/physreve.102.062140] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 11/18/2020] [Indexed: 11/07/2022]
Abstract
In this paper, we examine the virial- and the potential-energy correlation for quasireal model systems. This correlation constitutes the framework of the theory of the isomorph in the liquid phase diagram commonly examined using simple liquids. Interestingly, our results show that for the systems characterized by structural anisotropy and flexible bonds, the instantaneous values of total virial and total potential energy are entirely uncorrelated. It is due to the presence of the intramolecular interactions because the contributions to the virial and potential energy resulting from the intermolecular interactions still exhibit strong linear dependence. Interestingly, in contrast to the results reported for simple liquids, the slope of the mentioned linear dependence is different than the values of the density scaling exponent. However, our findings show that for quasireal materials, the slope of dependence between the virial and potential energy (resulting from the intermolecular interactions) strongly depends on the interval of intermolecular distances that are taken into account. Consequently, the value of the slope of the discussed relationship, which enables satisfactory density scaling, can be obtained. Interestingly, this conclusion is supported by the results obtained for analogous systems without intermolecular attraction, for which the value the slope of the virial-potential-energy correlation is independent of considered intermolecular distances, directly corresponds to the exponent of the intermolecular repulsion, and finally leads to accurate density scaling.
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Affiliation(s)
- K Koperwas
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland and Silesian Center for Education and Interdisciplinary Research SMCEBI, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
| | - A Grzybowski
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland and Silesian Center for Education and Interdisciplinary Research SMCEBI, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
| | - M Paluch
- University of Silesia in Katowice, Institute of Physics, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland and Silesian Center for Education and Interdisciplinary Research SMCEBI, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
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Holt AP, Fragiadakis D, Roland CM. Pressure densified 1,3,5-tri(1-naphthyl)benzene glass. I. Volume recovery and physical aging. J Chem Phys 2019; 151:184502. [PMID: 31731837 DOI: 10.1063/1.5122765] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effects of pressure densification on 1,3,5-tri(1-naphthyl)benzene (TNB) are assessed from volumetric and calorimetric measurements. The pressure densified glass (PDG) has higher density than conventional glass (CG), but unlike ultrastable TNB glass prepared using vapor deposition which also has elevated density, TNB PDG exhibits higher enthalpy and lower thermal stability than when formed at ambient pressure. PDG also exhibits anomalous physical aging. Rather than evolving monotonically toward the equilibrium density, there is an overshoot to a lower density state. Only when the density of the PDG becomes equivalent to the corresponding CG does the density begin a slow approach toward equilibrium.
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Affiliation(s)
- A P Holt
- Naval Research Laboratory, Chemistry Division, Washington, DC 20375-5342, USA
| | - D Fragiadakis
- 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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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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Fragiadakis D, Roland CM. Chain Flexibility and the Segmental Dynamics of Polymers. J Phys Chem B 2019; 123:5930-5934. [PMID: 31188607 DOI: 10.1021/acs.jpcb.9b04068] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using molecular dynamics simulations, we examine the dynamics of a family of model polymers with varying chain length and torsional potential barriers. We focus on features of the dynamics of polymers that are seen experimentally but absent in simulations of freely rotating and freely jointed chains. The reduced effect of volume on the segmental dynamics with increasing chain length, a capacity for pressure densification, and the deviation from constant Johari-Goldstein relaxation time at a constant segmental relaxation time all have a common origin, torsional rigidity, and these effects become increasingly apparent for more rigid chains.
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Affiliation(s)
- Daniel Fragiadakis
- Chemistry Division , Naval Research Laboratory , Washington , District of Columbia 20375-5342 , United States
| | - C Michael Roland
- Chemistry Division , Naval Research Laboratory , Washington , District of Columbia 20375-5342 , United States
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Holt AP, Fragiadakis D, Wollmershauser JA, Feigelson BN, Tyagi M, Roland CM. Stability Limits of Pressure Densified Polycarbonate Glass. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00603] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | - M. Tyagi
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6100, United States
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States
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Johari GP, Andersson O, Sundqvist B. Instability and thermal conductivity of pressure-densified and elastically altered orientational glass of Buckminsterfullerene. J Chem Phys 2018; 148:144502. [PMID: 29655324 DOI: 10.1063/1.5019832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report on the temperature, pressure, and time (T, p, and t)-dependent features of thermal conductivity, κ, of partially ordered, non-equilibrium state of C60-OG, the orientational glass of Buckminsterfullerene (at T below the orientational freezing temperature Tog) made more unstable (i) by partially depressurizing its high-p formed state to elastically expand it and (ii) by further pressurizing that state to elastically contract it. The sub-Tog effects observed on heating of C60-OG differ from those of glasses because phonon propagation depends on the ratio of two well-defined orientational states of C60 molecules and the density of the solid. A broad peak-like feature appears at T near Tog in the κ-T plots of C60-OG formed at 0.7 GPa, depressurized to 0.2 GPa and heated at 0.2 GPa, which we attribute to partial overlap of the sub-Tog and Tog features. A sub-Tog local minimum appears in the κ-T plots at T well below Tog of C60-OG formed at 0.1 GPa, pressurized to 0.5 GPa and heated at 0.5 GPa and it corresponds to the state of maximum disorder. Although Buckminsterfullerene is regarded as an orientationally disordered crystal, variation of its properties with T and p is qualitatively different from other such crystals. We discuss the findings in terms of the nature of its disorder, sensitivity of its rotational dynamics to temperature, and the absence of the Johari-Goldstein relaxation. All seem to affect the phenomenology of its glass-like transition.
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Affiliation(s)
- G P Johari
- Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada
| | - Ove Andersson
- Department of Physics, Umeå University, 901 87 Umeå, Sweden
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Johari GP. Increasing the Ambient Pressure Solubility by Forming a Glass at High Pressure and Its Thermodynamics, a Much Sought-After Pharmaceutical Advantage. J Phys Chem B 2018; 122:2031-2039. [DOI: 10.1021/acs.jpcb.7b12432] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- G. P. Johari
- Department of Materials Science and
Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada
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Casalini R, Roland CM. Communication: Effect of density on the physical aging of pressure-densified polymethylmethacrylate. J Chem Phys 2017; 147:091104. [PMID: 28886646 DOI: 10.1063/1.4995567] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The rate of physical aging of glassy polymethylmethacrylate (PMMA), followed from the change in the secondary relaxation with aging, is found to be independent of the density, the latter controlled by the pressure during glass formation. Thus, the aging behavior of the secondary relaxation is the same whether the glass is more compacted or less dense than the corresponding equilibrium liquid. This equivalence in aging of glasses formed under different pressures indicates that local packing is the dominant variable governing the glassy dynamics. The fact that pressure densification yields different glass structures is at odds with a model for non-associated materials having dynamic properties exhibited by PMMA, such as density scaling of the relaxation time and isochronal superposition of the relaxation dispersion.
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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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