51
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Jani A, Busch M, Mietner JB, Ollivier J, Appel M, Frick B, Zanotti JM, Ghoufi A, Huber P, Fröba M, Morineau D. Dynamics of water confined in mesopores with variable surface interaction. J Chem Phys 2021; 154:094505. [DOI: 10.1063/5.0040705] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Aîcha Jani
- Institute of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes, France
| | - Mark Busch
- Center for Integrated Multiscale Materials Systems (CIMMS), Hamburg University of Technology, 21073 Hamburg, Germany
| | - J. Benedikt Mietner
- Institute of Inorganic and Applied Chemistry, University of Hamburg, 20146 Hamburg, Germany
| | - Jacques Ollivier
- Institut Laue-Langevin, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Markus Appel
- Institut Laue-Langevin, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Bernhard Frick
- Institut Laue-Langevin, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Jean-Marc Zanotti
- Laboratoire Léon Brillouin, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Aziz Ghoufi
- Institute of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes, France
| | - Patrick Huber
- Center for Integrated Multiscale Materials Systems (CIMMS), Hamburg University of Technology, 21073 Hamburg, Germany
- Centre for X-ray and Nano Science (CXNS), Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany
- Centre for Hybrid Nanostructures (CHyN), Hamburg University, 22607 Hamburg, Germany
| | - Michael Fröba
- Institute of Inorganic and Applied Chemistry, University of Hamburg, 20146 Hamburg, Germany
| | - Denis Morineau
- Institute of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes, France
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52
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Miyazaki Y, Nakano M, Krivchikov AI, Koroyuk OA, Gebbia JF, Cazorla C, Tamarit JL. Low-Temperature Heat Capacity Anomalies in Ordered and Disordered Phases of Normal and Deuterated Thiophene. J Phys Chem Lett 2021; 12:2112-2117. [PMID: 33625859 PMCID: PMC8594864 DOI: 10.1021/acs.jpclett.1c00289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
We measured the specific heat Cp of normal (C4H4S) and deuterated (C4D4S) thiophene in the temperature interval of 1 ≤ T, K ≤ 25. C4H4S exhibits a metastable phase II2 and a stable phase V, both with frozen orientational disorder (OD), whereas C4D4S exhibits a metastable phase II2, which is analogous to the OD phase II2 of C4H4S and a fully ordered stable phase V. Our measurements demonstrate the existence of a large bump in the heat capacity of both stable and metastable C4D4S and C4H4S phases at temperatures of ∼10 K, which significantly departs from the expected Debye temperature behavior of Cp ≈ T3. This case study demonstrates that the identified low-temperature Cp anomaly, typically referred to as a "Boson-peak" in the context of glassy crystals, is not exclusive of disordered materials.
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Affiliation(s)
- Y. Miyazaki
- Research
Center for Thermal and Entropic Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Osaka, Japan
| | - M. Nakano
- Research
Center for Thermal and Entropic Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Osaka, Japan
| | - A. I. Krivchikov
- B.
Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences Ukraine, 47 Science Avenue, Kharkov 61103, Ukraine
| | - O. A. Koroyuk
- B.
Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences Ukraine, 47 Science Avenue, Kharkov 61103, Ukraine
| | - J. F. Gebbia
- Grup
de Caracterizació de Materials, Departament de Física,
EEBE and Barcelona Research Center in Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany, 10-14, Barcelona 08019, Catalonia, Spain
| | - C. Cazorla
- Departament
de Física, Universitat Politècnica
de Catalunya, Campus
Nord B4−B5, Barcelona E-08034, Catalonia, Spain
| | - J. Ll. Tamarit
- Grup
de Caracterizació de Materials, Departament de Física,
EEBE and Barcelona Research Center in Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany, 10-14, Barcelona 08019, Catalonia, Spain
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53
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Singh A, Bhattacharyya SM, Singh Y. Emergence of cooperatively reorganizing cluster and super-Arrhenius dynamics of fragile supercooled liquids. Phys Rev E 2021; 103:032611. [PMID: 33862818 DOI: 10.1103/physreve.103.032611] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
In this paper, we develop a theory to calculate the structural relaxation time τ_{α} of fragile supercooled liquids. Using the information of the configurational entropy and structure, we calculate the number of dynamically free, metastable, and stable neighbors around a central particle. In supercooled liquids, the cooperatively reorganizing clusters (CRCs) in which the stable neighbors form "stable" nonchemical bonds with the central particle emerge. For an event of relaxation to take place, these bonds have to reorganize irreversibly; the energy involved in the processes is the effective activation energy of relaxation. The theory brings forth a temperature T_{a} and a temperature-dependent parameter ψ(T) which characterize slowing down of dynamics on cooling. It is shown that the value of ψ(T) is equal to 1 for T>T_{a}, indicating that the underlying microscopic mechanism of relaxation is dominated by the entropy-driven processes, while for T<T_{a}, ψ(T) decreases on cooling, indicating the emergence of the energy-driven processes. This crossover of ψ(T) from high to low temperatures explains the crossover seen in τ_{α}. The dynamics of systems that may have similar static structure but very different dynamics can be understood in terms of ψ(T). We present results for the Kob-Anderson model for three densities and show that the calculated values of τ_{α} are in excellent agreement with simulation values for all densities. We also show that when ψ(T), τ_{α}, and other quantities are plotted as a function of T/T_{a} (or T_{a}/T), the data collapse on master curves.
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Affiliation(s)
- Ankit Singh
- Department of Physics, Banaras Hindu University, Varanasi 221 005, India
| | | | - Yashwant Singh
- Department of Physics, Banaras Hindu University, Varanasi 221 005, India
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54
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Xu WS, Douglas JF, Sun ZY. Polymer Glass Formation: Role of Activation Free Energy, Configurational Entropy, and Collective Motion. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02740] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Wen-Sheng Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Zhao-Yan Sun
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
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55
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Švajdlenková H, Šauša O, Adichtchev SV, Surovtsev NV, Novikov VN, Bartoš J. On the Mutual Relationships between Molecular Probe Mobility and Free Volume and Polymer Dynamics in Organic Glass Formers: cis-1,4-poly(isoprene). Polymers (Basel) 2021; 13:polym13020294. [PMID: 33477605 PMCID: PMC7831304 DOI: 10.3390/polym13020294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 11/16/2022] Open
Abstract
We report on the reorientation dynamics of small spin probe 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) in cis-1,4-poly(isoprene) (cis-1,4-PIP10k) from electron spin resonance (ESR) and the free volume of cis-1,4-PIP10k from positron annihilation lifetime spectroscopy (PALS) in relation to the high-frequency relaxations of cis-1,4-PIP10k using light scattering (LS) as well as to the slow and fast processes from broadband dielectric spectroscopy (BDS) and neutron scattering (NS). The hyperfine coupling constant, 2Azz
'(T), and the correlation times, τ
c(T), of cis-1,4-PIP10k/TEMPO system as a function of temperature exhibit several regions of the distinct spin probe TEMPO dynamics over a wide temperature range from 100 K up to 350 K. The characteristic ESR temperatures of changes in the spin probe dynamics in cis-1,4-PIP10k/TEMPO system are closely related to the characteristic PALS ones reflecting changes in the free volume expansion from PALS measurement. Finally, the time scales of the slow and fast dynamics of TEMPO in cis-1,4-PIP10k are compared with all of the six known slow and fast relaxation modes from BDS, LS and NS techniques with the aim to discuss the controlling factors of the spin probe reorientation mobility in polymer, oligomer and small molecular organic glass-formers.
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Affiliation(s)
- Helena Švajdlenková
- Polymer Institute of SAS, Dúbravská Cesta 9, 84541 Bratislava, Slovakia;
- Correspondence:
| | - Ondrej Šauša
- Institute of Physics of SAS, Dúbravská Cesta 9, 84511 Bratislava, Slovakia;
- Department of Nuclear Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska Dolina, Ilkovicova 6, 84215 Bratislava, Slovakia
| | - Sergey V. Adichtchev
- IA&E, Russian Academy of Sciences, 630090 Novosibirsk, Russia; (S.V.A.); (N.V.S.); (V.N.N.)
| | - Nikolay V. Surovtsev
- IA&E, Russian Academy of Sciences, 630090 Novosibirsk, Russia; (S.V.A.); (N.V.S.); (V.N.N.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Vladimir N. Novikov
- IA&E, Russian Academy of Sciences, 630090 Novosibirsk, Russia; (S.V.A.); (N.V.S.); (V.N.N.)
| | - Josef Bartoš
- Polymer Institute of SAS, Dúbravská Cesta 9, 84541 Bratislava, Slovakia;
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56
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Tourlakis GM, Adamopoulos SAT, Gavra IK, Milpanis AA, Tsagri LF, Pachygianni ASG, Chatzikokolis SS, Tsekouras AA. Sign flipping of spontaneous polarization in vapour-deposited films of small polar organic molecules. Phys Chem Chem Phys 2021; 23:14352-14362. [PMID: 34169950 DOI: 10.1039/d1cp01584b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Films of polar molecules vapour-deposited on sufficiently cold substrates are not only amorphous, but also exhibit charge polarization across their thickness. This is an effect known for 50 years, but it is very poorly understood and no mechanism exists in the literature that can explain and predict it. We investigated this bulk effect for 18 small organic molecules as a function of substrate temperature (30-130 K). We found that, as a rule, alcohol films have the negative end on the vacuum side at all temperatures. Alkyl acetates and toluene showed positive voltages which reached a maximum around the middle of the temperature range investigated. Tetrahydrofuran showed positive voltages which dropped with increasing deposition temperature. Diethyl ether, acetone, propanal, and butanal showed positive film voltages at low temperatures, negative at intermediate temperatures and again positive voltages at higher temperatures. In all cases, film voltages were monitored during heating leading to film evaporation. Film voltages were irreversibly eliminated before film elimination, but voltage profiles during temperature ramps differed vastly depending on compound and deposition temperature. In general, there was a gradual voltage reduction, but propanal, butanal, and diethyl ether showed a change in voltage sign during temperature ramp in films deposited at low temperatures. All these data expand substantially the experimental information regarding spontaneous polarization in vapour-deposited films, but still require complementary measurements as well as numerical simulations for a detailed explanation of the phenomenon.
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Affiliation(s)
- Georgios M Tourlakis
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
| | - Sotirios Alexandros T Adamopoulos
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
| | - Irini K Gavra
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
| | - Alexandros A Milpanis
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
| | - Liveria F Tsagri
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
| | - Aikaterini Sofia G Pachygianni
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
| | - Stylianos S Chatzikokolis
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
| | - Athanassios A Tsekouras
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, GR-15784, Greece.
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57
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Madkour S, Gawek M, Hertwig A, Schönhals A. Do Interfacial Layers in Thin Films Act as an Independent Layer within Thin Films? Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c02149] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Sherif Madkour
- Bundesanstalt für Materialforschung und −prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
| | - Marcel Gawek
- Bundesanstalt für Materialforschung und −prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
| | - Andreas Hertwig
- Bundesanstalt für Materialforschung und −prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
| | - Andreas Schönhals
- Bundesanstalt für Materialforschung und −prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
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58
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Bagchi K, Fiori ME, Bishop C, Toney MF, Ediger MD. Stable Glasses of Organic Semiconductor Resist Crystallization. J Phys Chem B 2020; 125:461-466. [DOI: 10.1021/acs.jpcb.0c09925] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kushal Bagchi
- Department of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Marie E. Fiori
- Department of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Camille Bishop
- Department of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - M. F. Toney
- SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
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59
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Banerjee S, Ghorai PK, Das S, Rajbangshi J, Biswas R. Heterogeneous dynamics, correlated time and length scales in ionic deep eutectics: Anion and temperature dependence. J Chem Phys 2020; 153:234502. [DOI: 10.1063/5.0024355] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Swarup Banerjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Kolkata, India
| | - Pradip Kr. Ghorai
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Kolkata, India
| | - Suman Das
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences, Kolkata, India
| | - Juriti Rajbangshi
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences, Kolkata, India
| | - Ranjit Biswas
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences, Kolkata, India
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60
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Weeks ER, Criddle K. Visualizing free-energy landscapes for four hard disks. Phys Rev E 2020; 102:062153. [PMID: 33466114 DOI: 10.1103/physreve.102.062153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 12/09/2020] [Indexed: 06/12/2023]
Abstract
We present a simple model system with four hard disks moving in a circular region for which free-energy landscapes can be directly calculated and visualized in two and three dimensions. We construct several energy landscapes for our system, and we explore the strengths and limitations of each in terms of understanding system dynamics, in particular the relationship between state transitions and free-energy barriers. We also demonstrate the importance of distinguishing between system dynamics in real space and those in landscape coordinates, and we show that care must be taken to appropriately combine dynamics with barrier properties to understand the transition rates. This simple model provides an intuitive way to understand free-energy landscapes, and it illustrates the benefits that free-energy landscapes can have over potential energy landscapes.
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Affiliation(s)
- Eric R Weeks
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
| | - Keely Criddle
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
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61
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Marple MAT, Wynn TA, Cheng D, Shimizu R, Mason HE, Meng YS. Local Structure of Glassy Lithium Phosphorus Oxynitride Thin Films: A Combined Experimental and Ab Initio Approach. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202009501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Maxwell A. T. Marple
- Physical and Life Science Directorate Lawrence Livermore National Laboratory Livermore CA 94550 USA
| | - Thomas A. Wynn
- Department Department of NanoEngineering University of California San Diego La Jolla CA 92093 USA
| | - Diyi Cheng
- Materials Science & Engineering Program University of California San Diego La Jolla CA 92093 USA
| | - Ryosuke Shimizu
- Department Department of NanoEngineering University of California San Diego La Jolla CA 92093 USA
| | - Harris E. Mason
- Physical and Life Science Directorate Lawrence Livermore National Laboratory Livermore CA 94550 USA
| | - Y. Shirley Meng
- Department Department of NanoEngineering University of California San Diego La Jolla CA 92093 USA
- Materials Science & Engineering Program University of California San Diego La Jolla CA 92093 USA
- Sustainable Power and Energy Center University of California San Diego La Jolla CA 92093 USA
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62
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Ghosh A, Schweizer KS. The role of collective elasticity on activated structural relaxation, yielding, and steady state flow in hard sphere fluids and colloidal suspensions under strong deformation. J Chem Phys 2020; 153:194502. [DOI: 10.1063/5.0026258] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ashesh Ghosh
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, USA
| | - Kenneth S. Schweizer
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, USA
- Department of Material Science, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, USA
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, USA
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63
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Alzate-Vargas L, Onofrio N, Strachan A. Universality in Spatio-Temporal High-Mobility Domains Across the Glass Transition from Bulk Polymers to Single Chains. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00853] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lorena Alzate-Vargas
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Nicolas Onofrio
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR
| | - Alejandro Strachan
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
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64
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Egami T, Ryu CW. Why Is the Range of Timescale So Wide in Glass-Forming Liquid? Front Chem 2020; 8:579169. [PMID: 33134277 PMCID: PMC7550744 DOI: 10.3389/fchem.2020.579169] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/27/2020] [Indexed: 11/13/2022] Open
Abstract
The viscosity and the relaxation time of a glass-forming liquid vary over 15 orders of magnitude before the liquid freezes into a glass. The rate of the change with temperature is characterized by liquid fragility. The mechanism of such a spectacular behavior and the origin of fragility have long been discussed, but it remains unresolved because of the difficulty of carrying out experiments and constructing theories that bridge over a wide timescale from atomic (ps) to bulk (minutes). Through the x-ray diffraction measurement and molecular dynamics simulation for metallic liquids we suggest that large changes in viscosity can be caused by relatively small changes in the structural coherence which characterizes the medium-range order. Here the structural coherence does not imply that of atomic-scale structure, but it relates to the coarse-grained density fluctuations represented by the peaks in the pair-distribution function (PDF) beyond the nearest neighbors. The coherence length is related to fragility and increases with decreasing temperature, and it diverges only at a negative temperature. This analysis is compared with several current theories which predict a phase transition near the glass transition temperature.
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Affiliation(s)
- Takeshi Egami
- Department of Materials Science and Engineering, Shull-Wollan Center - Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, Knoxville, TN, United States.,Department of Physics and Astronomy, University of Tennessee, Knoxville, Knoxville, TN, United States.,Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Chae Woo Ryu
- Department of Materials Science and Engineering, Shull-Wollan Center - Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, Knoxville, TN, United States
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65
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Kirova EM, Pisarev VV. Morphological aspect of crystal nucleation in wall-confined supercooled metallic film. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 33:034003. [PMID: 33078713 DOI: 10.1088/1361-648x/abba6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 09/21/2020] [Indexed: 06/11/2023]
Abstract
In this paper, we simulate the nucleation and growth of crystalline nuclei in a molybdenum film cooled at different rates confined between two amorphous walls. We also compare the results for the wall-confined and wall-free systems. We apply the same methodology as in the work (Kirova and Pisarev 2019J. Cryst. Growth528125266) which is based on reconstructing the probability density function for the largest crystalline nucleus in the system. The size of the nucleus and the asphericity parameter are considered as the reaction coordinates. We demonstrate that in both the free and confined systems there are two mechanisms of crystal growth: the attachment of atoms to the biggest crystal from the amorphous phase and the merging of the biggest crystal cluster with small ones (coalescence). We show that the attachment mechanism is dominant in the melt cooled down at a slower rate, and the mechanism gradually shifts to coalescence as cooling rate increases. We also observe the formation of long-lived crystal clusters and demonstrate that amorphous walls do not affect their geometric characteristics. However, system confined between walls demonstrates higher glass-forming ability.
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Affiliation(s)
- E M Kirova
- National Research University Higher School of Economics, 20 Myasnitskaya str., 101000 Moscow, Russia
- Joint Institute for High Temperatures of RAS, 13/2 Izhorskaya str., 125412 Moscow, Russia
| | - V V Pisarev
- National Research University Higher School of Economics, 20 Myasnitskaya str., 101000 Moscow, Russia
- Joint Institute for High Temperatures of RAS, 13/2 Izhorskaya str., 125412 Moscow, Russia
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66
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Ivancic RJS, Riggleman RA. Dynamic phase transitions in freestanding polymer thin films. Proc Natl Acad Sci U S A 2020; 117:25407-25413. [PMID: 33008880 PMCID: PMC7568329 DOI: 10.1073/pnas.2006703117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
After more than two decades of study, many fundamental questions remain unanswered about the dynamics of glass-forming materials confined to thin films. Experiments and simulations indicate that free interfaces enhance dynamics over length scales larger than molecular sizes, and this effect strengthens at lower temperatures. The nature of the influence of interfaces, however, remains a point of significant debate. In this work, we explore the properties of the nonequilibrium phase transition in dynamics that occurs in trajectory space between high- and low-mobility basins in a set of model polymer freestanding films. In thick films, the film-averaged mobility transition is broader than the bulk mobility transition, while in thin films it is a variant of the bulk result shifted toward a higher bias. Plotting this transition's local coexistence points against the distance from the films' surface shows thick films have surface and film-center transitions, while thin films practically have a single transition throughout the film. These observations are reminiscent of thermodynamic capillary condensation of a vapor-liquid phase between parallel plates, suggesting they constitute a demonstration of such an effect in a trajectory phase transition in the dynamics of a structural glass former. Moreover, this transition bears similarities to several experiments exhibiting anomalous behavior in the glass transition upon reducing film thickness below a material-dependent onset, including the broadening of the glass transition and the homogenization of surface and bulk glass transition temperatures.
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Affiliation(s)
- Robert J S Ivancic
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert A Riggleman
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, 19104
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67
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Marple MAT, Wynn TA, Cheng D, Shimizu R, Mason HE, Meng YS. Local Structure of Glassy Lithium Phosphorus Oxynitride Thin Films: A Combined Experimental and Ab Initio Approach. Angew Chem Int Ed Engl 2020; 59:22185-22193. [PMID: 32818306 DOI: 10.1002/anie.202009501] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Indexed: 11/10/2022]
Abstract
Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. Herein, we provide a structural model of RF-sputtered LiPON. Information about the short-range structure results from 1D and 2D solid-state NMR experiments. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility, highlighting the unique mechanical properties of glassy materials.
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Affiliation(s)
- Maxwell A T Marple
- Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Thomas A Wynn
- Department Department of NanoEngineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Diyi Cheng
- Materials Science & Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Ryosuke Shimizu
- Department Department of NanoEngineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Harris E Mason
- Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Y Shirley Meng
- Department Department of NanoEngineering, University of California San Diego, La Jolla, CA, 92093, USA.,Materials Science & Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA.,Sustainable Power and Energy Center, University of California San Diego, La Jolla, CA, 92093, USA
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68
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Zheng W, Lei QL, Ma Y, Ni R. Hierarchical glass transition of hard hemidisks with local assemblies. SOFT MATTER 2020; 16:8108-8113. [PMID: 32896848 DOI: 10.1039/d0sm01003k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Using computer simulation, we investigate the glass transition of a two-dimensional hard-hemidisk system. Upon increasing the packing fraction of the system, we find that the system vitrifies into a glass with local assembled discal "dimers", which are free to rotate in a collective way. The rotational mean square displacement does not exhibit the typical plateau (slowdown) like what occurs in the translational mean square displacement. This effect induces a pronounced violation of the rotational Stokes-Einstein relationship compared with the translational degree of freedom at the supercooled region. However, the obtained glass transition points in these two freedom degrees are found to be the same within the numerical accuracy, which is due to the strong positive spatial and dynamic correlation between translational and rotational slow-moving particles. Moreover, we find that the locally assembled dimers can serve as fast rotating gears facilitating the orientational relaxation in the system, and this suggests that the locally favored finite structures play an important role in the hierarchical glass transition of anisotropic colloids.
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Affiliation(s)
- Wei Zheng
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China. and School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore.
| | - Qun-Li Lei
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore.
| | - Yuqiang Ma
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
| | - Ran Ni
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore.
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69
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Royall CP, Turci F, Speck T. Dynamical phase transitions and their relation to structural and thermodynamic aspects of glass physics. J Chem Phys 2020; 153:090901. [PMID: 32891096 DOI: 10.1063/5.0006998] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We review recent developments in structural-dynamical phase transitions in trajectory space based on dynamic facilitation theory. An open question is how the dynamic facilitation perspective on the glass transition may be reconciled with thermodynamic theories that posit collective reorganization accompanied by a growing static length scale and, eventually, a vanishing configurational entropy. In contrast, dynamic facilitation theory invokes a dynamical phase transition between an active phase (close to the normal liquid) and an inactive phase, which is glassy and whose order parameter is either a time-averaged dynamic or structural quantity. In particular, the dynamical phase transition in systems with non-trivial thermodynamics manifests signatures of a lower critical point that lies between the mode-coupling crossover and the putative Kauzmann temperature, at which a thermodynamic phase transition to an ideal glass state would occur. We review these findings and discuss such criticality in the context of the low-temperature decrease in configurational entropy predicted by thermodynamic theories of the glass transition.
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Affiliation(s)
- C Patrick Royall
- HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Francesco Turci
- HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
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70
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Xie SJ, Schweizer KS. Microscopic Theory of Dynamically Heterogeneous Activated Relaxation as the Origin of Decoupling of Segmental and Chain Relaxation in Supercooled Polymer Melts. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00849] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shi-Jie Xie
- Departments of Materials Science, University of Illinois, Urbana, Illinois 61801, United States
- Material Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
- Center for Membrane Separation and Water Science & Technology, Ocean College, Zhejiang University of Technology, Hangzhou 310014, PR China
| | - Kenneth S. Schweizer
- Departments of Materials Science, University of Illinois, Urbana, Illinois 61801, United States
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
- Material Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
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71
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Bender JS, Zhi M, Cicerone MT. The polarizability response of a glass-forming liquid reveals intrabasin motion and interbasin transitions on a potential energy landscape. SOFT MATTER 2020; 16:5588-5598. [PMID: 32057068 DOI: 10.1039/c9sm02326g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Potential energy landscape (PEL) concepts have been useful in conceptualizing the effects of intermolecular interactions on dynamic and thermodynamic properties of liquids and glasses. "Basins", or regions of reduced potential energy associated with locally preferred molecular packing are important PEL features. The molecular configurations at the bottom of these basins are referred to as inherent structures (ISs). Experimental methods for directly characterizing PEL features such as these are rare, largely relegating PEL concepts to theory and simulation studies, and impeding their exploration in real systems. Recently, we showed that quasielastic neutron scattering (QENS) data from propylene carbonate (PC) exhibit signatures of picosecond timescale motion that are consistent with intrabasin motion and interbasin transitions [Cicerone et al., J. Chem. Phys., 2017, 146, 054502]. Here we present optically-heterodyne-detected optical Kerr effect (OHD-OKE) spectroscopy studies on PC. The data exhibit signatures of motion within and transitions between basins that agree quantitatively with and extend the QENS results. We show that the librational component of the OKE response corresponds to intrabasin dynamics, and the enigmatic intermediate OKE response corresponds to interbasin transition events. The OKE data extend the measurement range of these parameters and reveal their utility in characterizing PEL features of real systems.
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Affiliation(s)
- John S Bender
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Miaochan Zhi
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Marcus T Cicerone
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA and Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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72
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Bagchi K, Deng C, Bishop C, Li Y, Jackson NE, Yu L, Toney MF, de Pablo JJ, Ediger MD. Over What Length Scale Does an Inorganic Substrate Perturb the Structure of a Glassy Organic Semiconductor? ACS APPLIED MATERIALS & INTERFACES 2020; 12:26717-26726. [PMID: 32402187 DOI: 10.1021/acsami.0c06428] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
While the bulk structure of vapor-deposited glasses has been extensively studied, structure at buried interfaces has received little attention, despite being important for organic electronic applications. To learn about glass structure at buried interfaces, we study the structure of vapor-deposited glasses of the organic semiconductor DSA-Ph (1,4-di-[4-(N,N-diphenyl)amino]styrylbenzene) as a function of film thickness; the structure is probed with grazing incidence X-ray scattering. We deposit on silicon and gold substrates and span a film thickness range of 10-600 nm. Our experiments demonstrate that interfacial molecular packing in vapor-deposited glasses of DSA-Ph is more disordered compared to the bulk. At a deposition temperature near room temperature, we estimate ∼8 nm near the substrate can have modified molecular packing. Molecular dynamics simulations of a coarse-grained representation of DSA-Ph reveal a similar length scale. In both the simulations and the experiments, deposition temperature controls glass structure beyond this interfacial layer of a few nanometers.
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Affiliation(s)
- Kushal Bagchi
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Chuting Deng
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Camille Bishop
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Yuhui Li
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, United States
| | - Nicholas E Jackson
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
- Center for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Lian Yu
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, United States
| | - M F Toney
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - J J de Pablo
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
- Center for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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73
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Heyes DM, Dini D, Smith ER. Single trajectory transport coefficients and the energy landscape by molecular dynamics simulations. J Chem Phys 2020; 152:194504. [PMID: 33687256 DOI: 10.1063/5.0005600] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Green-Kubo (GK) method is widely used to calculate the transport coefficients of model liquids by Molecular Dynamics (MD) simulation. A reformulation of GK was proposed by Heyes et al. [J. Chem. Phys. 150, 174504 (2019)], which expressed the shear viscosity in terms of a probability distribution function (PDF) of "single trajectory (ST) viscosities," called "viscuits." This approach is extended here to the bulk viscosity, thermal conductivity, and diffusion coefficient. The PDFs of the four STs expressed in terms of their standard deviations (calculated separately for the positive and negative sides) are shown by MD to be statistically the same for the Lennard-Jones fluid. This PDF can be represented well by a sum of exponentials and is independent of system size and state point in the equilibrium fluid regime. The PDF is not well reproduced by a stochastic model. The PDF is statistically the same as that derived from the potential energy, u, and other thermodynamic quantities, indicating that the transport coefficients are determined quantitatively by and follow closely the time evolution of the underlying energy landscape. The PDFs of out-of-equilibrium supercooled high density states are quite different from those of the equilibrium states.
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Affiliation(s)
- D M Heyes
- Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, United Kingdom
| | - D Dini
- Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, United Kingdom
| | - E R Smith
- Department of Mechanical and Aerospace Engineering, Brunel University London, Uxbridge, Middlesex UB8 3PH, United Kingdom
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74
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Eng J, Penfold TJ. Understanding and Designing Thermally Activated Delayed Fluorescence Emitters: Beyond the Energy Gap Approximation. CHEM REC 2020; 20:831-856. [PMID: 32267093 DOI: 10.1002/tcr.202000013] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/13/2020] [Indexed: 11/08/2022]
Abstract
In this article recent progress in the development of molecules exhibiting Thermally Activated Delayed Fluorescence (TADF) is discussed with a particular focus upon their application as emitters in highly efficient organic light emitting diodes (OLEDs). The key aspects controlling the desirable functional properties, e. g. fast intersystem crossing, high radiative rate and unity quantum yield, are introduced with a particular focus upon the competition between the key requirements needed to achieve high performance OLEDs. The design rules required for organic and metal organic materials are discussed, and the correlation between them outlined. Recent progress towards understanding the influence of the interaction between a molecule and its environment are explained as is the role of the mechanism for excited state formation in OLEDs. Finally, all of these aspects are combined to discuss the ability to implement high level design rules for achieving higher quality materials for commercial applications. This article highlights the significant progress that has been made in recent years, but also outlines the significant challenges which persist to achieve a full understanding of the TADF mechanism and improve the stability and performance of these materials.
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Affiliation(s)
- Julien Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Thomas J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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75
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Cho HW, Mugnai ML, Kirkpatrick TR, Thirumalai D. Fragile-to-strong crossover, growing length scales, and dynamic heterogeneity in Wigner glasses. Phys Rev E 2020; 101:032605. [PMID: 32290023 DOI: 10.1103/physreve.101.032605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/26/2020] [Indexed: 06/11/2023]
Abstract
Colloidal particles, which are ubiquitous, have become ideal testing grounds for the structural glass transition theories. In these systems glassy behavior arises as the density of the particles is increased. Thus, soft colloidal particles with varying degree of softness capture diverse glass-forming properties, observed normally in molecular glasses. Brownian dynamics simulations for a binary mixture of micron-sized charged colloidal suspensions show that tuning the softness of the interaction potential, achievable by changing the monovalent salt concentration results in a continuous transition from fragile to strong behavior. Remarkably, this is found in a system where the well characterized interaction potential between the colloidal particles is isotropic. We also show that the predictions of the random first-order transition (RFOT) theory quantitatively describes the universal features such as the growing correlation length, ξ∼(ϕ_{K}/ϕ-1)^{-ν} with ν=2/3 where ϕ_{K}, the analog of the Kauzmann temperature, depends on the salt concentration. As anticipated by the RFOT predictions, we establish a causal relationship between the growing correlation length and a steep increase in the relaxation time and dynamic heterogeneity as the system is compressed. The broad range of fragility observed in Wigner glasses is used to draw analogies with molecular and polymer glasses. The large variations in the fragility are normally found only when the temperature dependence of the viscosity is examined for a large class of diverse glass-forming materials. In sharp contrast, this is vividly illustrated in a single system that can be experimentally probed. Our work also shows that the RFOT predictions are accurate in describing the dynamics over the entire density range, regardless of the fragility of the glasses.
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Affiliation(s)
- Hyun Woo Cho
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - Mauro L Mugnai
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - T R Kirkpatrick
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - D Thirumalai
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
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76
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Yildirim A, Krause C, Zorn R, Lohstroh W, Schneider GJ, Zamponi M, Holderer O, Frick B, Schönhals A. Complex molecular dynamics of a symmetric model discotic liquid crystal revealed by broadband dielectric, thermal and neutron spectroscopy. SOFT MATTER 2020; 16:2005-2016. [PMID: 32003764 DOI: 10.1039/c9sm02487e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The molecular dynamics of the triphenylene-based discotic liquid crystal HAT6 is investigated by broadband dielectric spectroscopy, advanced dynamical calorimetry and neutron scattering. Differential scanning calorimetry in combination with X-ray scattering reveals that HAT6 has a plastic crystalline phase at low temperatures, a hexagonally ordered liquid crystalline phase at higher temperatures and undergoes a clearing transition at even higher temperatures. The dielectric spectra show several relaxation processes: a localized γ-relaxation at lower temperatures and a so called α2-relaxation at higher temperatures. The relaxation rates of the α2-relaxation have a complex temperature dependence and bear similarities to a dynamic glass transition. The relaxation rates estimated by Hyper DSC, Fast Scanning calorimetry and AC Chip calorimetry have a different temperature dependence than the dielectric α2-relaxation and follow the VFT-behavior characteristic for glassy dynamics. Therefore, this process is called α1-relaxation. Its relaxation rates show a similarity with that of polyethylene. For this reason, the α1-relaxation is assigned to the dynamic glass transition of the alkyl chains in the intercolumnar space. Moreover, this process is not observed by dielectric spectroscopy, which supports its assignment. The α2-relaxation is assigned to small scale translatorial and/or small angle fluctuations of the cores. The neutron scattering data reveal two relaxation processes. The process observed at shorter relaxation times is assigned to the methyl group rotation. The second relaxation process at longer time scales agree in the temperature dependence of its relaxation rates with that of the dielectric γ-relaxation.
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Affiliation(s)
- Arda Yildirim
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
| | - Christina Krause
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
| | - Reiner Zorn
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS-1) and Institute for Complex Systems (ICS-1), 52425 Jülich, Germany
| | - Wiebke Lohstroh
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Gerald J Schneider
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ, Lichtenbergstr. 1, 85748 Garching, Germany
| | - Michaela Zamponi
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ, Lichtenbergstr. 1, 85748 Garching, Germany
| | - Olaf Holderer
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ, Lichtenbergstr. 1, 85748 Garching, Germany
| | - Bernhard Frick
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Andreas Schönhals
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
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77
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Ginzburg VV. A simple mean-field model of glassy dynamics and glass transition. SOFT MATTER 2020; 16:810-825. [PMID: 31840706 DOI: 10.1039/c9sm01575b] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We propose a phenomenological model to describe the equilibrium dynamic behavior of amorphous glassy materials. It is assumed that a material can be represented by a lattice of cooperatively re-arranging regions (CRRs), with each CRR having two states, the low-temperature "solid" and the high-temperature "liquid". At low temperatures, the material exhibits two characteristic relaxation times, corresponding to the slow large-scale motion between the "solid" CRRs (α-relaxation) and the faster local motion within individual CRRs (β-relaxation). At high temperatures, the α- and β-relaxation times merge, as observed experimentally and suggested by the "Coupling Model" framework. Our new approach is labeled "Two-state, two (time)scale model" or TS2. It is shown that the TS2 treatment can successfully describe the "two-Arrhenius" relaxation time behavior described in several recent experiments. We also apply TS2 to describe the pressure- and molecular-weight dependence of the glass transition temperature in bulk polymers, as well as its dependence on film thickness in thin films.
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Affiliation(s)
- Valeriy V Ginzburg
- Core Research and Development, The Dow Chemical Company, Midland, MI 48674, USA.
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78
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Xie SJ, Schweizer KS. A collective elastic fluctuation mechanism for decoupling and stretched relaxation in glassy colloidal and molecular liquids. J Chem Phys 2020; 152:034502. [DOI: 10.1063/1.5129550] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Shi-Jie Xie
- Department of Materials Science, University of Illinois, Urbana, Illinois 61801, USA
- Material Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
- Center for Membrane Separation and Water Science and Technology, Ocean College, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Kenneth S. Schweizer
- Department of Materials Science, University of Illinois, Urbana, Illinois 61801, USA
- Material Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA
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79
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Campo M, Speck T. Dynamical coexistence in moderately polydisperse hard-sphere glasses. J Chem Phys 2020; 152:014501. [DOI: 10.1063/1.5134842] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Matteo Campo
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
| | - Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
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80
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Hansen HW, Lundin F, Adrjanowicz K, Frick B, Matic A, Niss K. Density scaling of structure and dynamics of an ionic liquid. Phys Chem Chem Phys 2020; 22:14169-14176. [DOI: 10.1039/d0cp01258k] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The lines in the pressure–temperature phase diagram with constant conductivity are found to be lines where other dynamic variables as well as the molecular structure factor peak are constant, while charge ordering changes.
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Affiliation(s)
- Henriette Wase Hansen
- Glass and Time
- IMFUFA
- Department of Science and Environment
- Roskilde University
- DK-4000 Roskilde
| | - Filippa Lundin
- Materials Physics
- Department of Physics
- Chalmers University of Technology
- Gothenburg
- Sweden
| | | | | | - Aleksandar Matic
- Materials Physics
- Department of Physics
- Chalmers University of Technology
- Gothenburg
- Sweden
| | - Kristine Niss
- Glass and Time
- IMFUFA
- Department of Science and Environment
- Roskilde University
- DK-4000 Roskilde
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81
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Rabideau BD, Soltani M, Parker RA, Siu B, Salter EA, Wierzbicki A, West KN, Davis JH. Tuning the melting point of selected ionic liquids through adjustment of the cation's dipole moment. Phys Chem Chem Phys 2020; 22:12301-12311. [PMID: 32432261 DOI: 10.1039/d0cp01214a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In previous work with thermally robust salts [Cassity et al., Phys. Chem. Chem. Phys., 2017, 19, 31560] it was noted that an increase in the dipole moment of the cation generally led to a decrease in the melting point. Molecular dynamics simulations of the liquid state revealed that an increased dipole moment reduces cation-cation repulsions through dipole-dipole alignment. This was believed to reduce the liquid phase enthalpy, which would tend to lower the melting point of the IL. In this work we further test this principle by replacing hydrogen atoms with fluorine atoms at selected positions within the cation. This allows us to alter the electrostatics of the cation without substantially affecting the sterics. Furthermore, the strength of the dipole moment can be controlled by choosing different positions within the cation for replacement. We studied variants of four different parent cations paired with bistriflimide and determined their melting points, and enthalpies and entropies of fusion through DSC experiments. The decreases in the melting point were determined to be enthalpically driven. We found that the dipole moment of the cation, as determined by quantum chemical calculations, is inversely correlated with the melting point of the given compound. Molecular dynamics simulations of the crystalline and solid states of two isomers showed differences in their enthalpies of fusion that closely matched those seen experimentally. Moreover, this reduction in the enthalpy of fusion was determined to be caused by an increase in the enthalpy of the crystalline state. We provide evidence that dipole-dipole interactions between cations leads to the formation of cationic domains in the crystalline state. These cationic associations partially block favourable cation-anion interactions, which are recovered upon melting. If, however, the dipole-dipole interactions between cations is too strong they have a tendency to form glasses. This study provides a design rule for lowering the melting point of structurally similar ILs by altering their dipole moment.
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Affiliation(s)
- Brooks D Rabideau
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Mohammad Soltani
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Rome A Parker
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Benjamin Siu
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - E Alan Salter
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Andrzej Wierzbicki
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Kevin N West
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - James H Davis
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
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82
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Schweizer KS, Simmons DS. Progress towards a phenomenological picture and theoretical understanding of glassy dynamics and vitrification near interfaces and under nanoconfinement. J Chem Phys 2019; 151:240901. [PMID: 31893888 DOI: 10.1063/1.5129405] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The nature of alterations to dynamics and vitrification in the nanoscale vicinity of interfaces-commonly referred to as "nanoconfinement" effects on the glass transition-has been an open question for a quarter century. We first analyze experimental and simulation results over the last decade to construct an overall phenomenological picture. Key features include the following: after a metrology- and chemistry-dependent onset, near-interface relaxation times obey a fractional power law decoupling relation with bulk relaxation; relaxation times vary in a double-exponential manner with distance from the interface, with an intrinsic dynamical length scale appearing to saturate at low temperatures; the activation barrier and vitrification temperature Tg approach bulk behavior in a spatially exponential manner; and all these behaviors depend quantitatively on the nature of the interface. We demonstrate that the thickness dependence of film-averaged Tg for individual systems provides a poor basis for discrimination between different theories, and thus we assess their merits based on the above dynamical gradient properties. Entropy-based theories appear to exhibit significant inconsistencies with the phenomenology. Diverse free-volume-motivated theories vary in their agreement with observations, with approaches invoking cooperative motion exhibiting the most promise. The elastically cooperative nonlinear Langevin equation theory appears to capture the largest portion of the phenomenology, although important aspects remain to be addressed. A full theoretical understanding requires improved confrontation with simulations and experiments that probe spatially heterogeneous dynamics within the accessible 1-ps to 1-year time window, minimal use of adjustable parameters, and recognition of the rich quantitative dependence on chemistry and interface.
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Affiliation(s)
- Kenneth S Schweizer
- Departments of Materials Science, Chemistry and Chemical & Biomolecular Engineering, Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
| | - David S Simmons
- Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, Florida 33620, USA
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83
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Tripodo A, Puosi F, Malvaldi M, Leporini D. Vibrational scaling of the heterogeneous dynamics detected by mutual information. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:146. [PMID: 31754931 DOI: 10.1140/epje/i2019-11916-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/03/2019] [Indexed: 06/10/2023]
Abstract
The correlations detected by the mutual information in the propensities of a molecular viscous liquid are studied by molecular-dynamics simulations. Dynamic heterogeneity is evidenced and two particle fractions with different mobility and relaxation identified. The two fractions exhibit the scaling of their relaxation in terms of the rattling amplitude of the particle trapped in the cage of the first neighbours 〈u2〉 . The scaling master curve does not differ from the one found for bulk systems, thus confirming identical results previously reported in other systems with strong dynamic heterogeneity as thin molecular films. The excitation of planar and globular structures at short and long times with respect to structural relaxation, respectively, is revealed. Some of the globular structures are different from the ones evidenced in atomic mixtures. States with equal 〈u2〉 are found to have identical time dependence of several quantities, referring to both bulk and the two fractions with heterogeneous dynamics, at least up to the structural relaxation time [Formula: see text].
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Affiliation(s)
- Antonio Tripodo
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
| | - Francesco Puosi
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
| | - Marco Malvaldi
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
| | - Dino Leporini
- Dipartimento di Fisica "Enrico Fermi", Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy.
- IPCF-CNR, UOS, Pisa, Italy.
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84
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The Proton Density of States in Confined Water (H 2O). Int J Mol Sci 2019; 20:ijms20215373. [PMID: 31671726 PMCID: PMC6861890 DOI: 10.3390/ijms20215373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/17/2019] [Accepted: 10/24/2019] [Indexed: 12/05/2022] Open
Abstract
The hydrogen density of states (DOS) in confined water has been probed by inelastic neutron scattering spectra in a wide range of its P–T phase diagram. The liquid–liquid transition and the dynamical crossover from the fragile (super-Arrhenius) to strong (Arrhenius) glass forming behavior have been studied, by taking into account the system polymorphism in both the liquid and amorphous solid phases. The interest is focused in the low energy region of the DOS (E<10 meV) and the data are discussed in terms of the energy landscape (local minima of the potential energy) approach. In this latest research, we consider a unit scale energy (EC) linked to the water local order governed by the hydrogen bonding (HB). All the measured spectra, scaled according to such energy, evidence a universal power law behavior with different exponents (γ) in the strong and fragile glass forming regions, respectively. In the first case, the DOS data obey the Debye squared-frequency law, whereas, in the second one, we obtain a value predicted in terms of the mode-coupling theory (MCT) (γ≃1.6).
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85
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Bachler J, Handle PH, Giovambattista N, Loerting T. Glass polymorphism and liquid-liquid phase transition in aqueous solutions: experiments and computer simulations. Phys Chem Chem Phys 2019; 21:23238-23268. [PMID: 31556899 DOI: 10.1039/c9cp02953b] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
One of the most intriguing anomalies of water is its ability to exist as distinct amorphous ice forms (glass polymorphism or polyamorphism). This resonates well with the possible first-order liquid-liquid phase transition (LLPT) in the supercooled state, where ice is the stable phase. In this Perspective, we review experiments and computer simulations that search for LLPT and polyamorphism in aqueous solutions containing salts and alcohols. Most studies on ionic solutes are devoted to NaCl and LiCl; studies on alcohols have mainly focused on glycerol. Less attention has been paid to protein solutions and hydrophobic solutes, even though they reveal promising avenues. While all solutions show polyamorphism and an LLPT only in dilute, sub-eutectic mixtures, there are differences regarding the nature of the transition. Isocompositional transitions for varying mole fractions are observed in alcohol but not in ionic solutions. This is because water can surround alcohol molecules either in a low- or high-density configuration whereas for ionic solutes, the water ion hydration shell is forced into high-density structures. Consequently, the polyamorphic transition and the LLPT are prevented near the ions, but take place in patches of water within the solutions. We highlight discrepancies and different interpretations within the experimental community as well as the key challenges that need consideration when comparing experiments and simulations. We point out where reinterpretation of past studies helps to draw a unified, consistent picture. In addition to the literature review, we provide original experimental results. A list of eleven open questions that need further consideration is identified.
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Affiliation(s)
- Johannes Bachler
- Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria.
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86
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Choi J, Lee S, Choe J, Chung Y, Lee YE, Kim J, Kim M, Paeng K. How Tethered Probes Report the Dynamics of a Polymer near the Glass Transition. ACS Macro Lett 2019; 8:1181-1186. [PMID: 35619450 DOI: 10.1021/acsmacrolett.9b00423] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
How tethered probes report dynamics of host polymers near the glass transition was investigated by changing the length of the flexible linkers and the number of tethering points via imaging rotational fluorescence correlation microscopy and compared with free probes of different sizes. The results show that tethering did not alter the temperature-dependence of polymer dynamics and the shape of the correlation decay reported by the probe; however, the rotation slowed down up to ≈1 decade when both ends of the probe were restricted with short alkyl chain linkers. Upon comparison with the bigger free probe, the mechanism of the slowdown was attributed to the restricted motion upon tethering for tethered probes compared to averaging over different regions of the dynamic heterogeneity for the bigger probe. If the size of the probe was comparable to that of the dynamic heterogeneity of the system, tethered probes accurately report dynamics relevant to glass transition, regardless of tethering conditions.
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Affiliation(s)
- Jiwon Choi
- Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Soohyun Lee
- Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jongwon Choe
- Department of Chemistry and Chemical Engineering, Inha University, Incheon 22212, Republic of Korea
| | - Yura Chung
- Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Yae Eun Lee
- Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jisu Kim
- Department of Chemistry and Chemical Engineering, Inha University, Incheon 22212, Republic of Korea
| | - Myungwoong Kim
- Department of Chemistry and Chemical Engineering, Inha University, Incheon 22212, Republic of Korea
| | - Keewook Paeng
- Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea
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87
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Iyer SS, Tripathy M, Srivastava A. Fluid Phase Coexistence in Biological Membrane: Insights from Local Nonaffine Deformation of Lipids. Biophys J 2019; 115:117-128. [PMID: 29972803 DOI: 10.1016/j.bpj.2018.05.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 05/10/2018] [Accepted: 05/15/2018] [Indexed: 01/09/2023] Open
Abstract
Lateral heterogeneities in biomembranes play a crucial role in various physiological functions of the cell. Such heterogeneities lead to demixing of lipid constituents and formation of distinct liquid domains in the membrane. We study lateral heterogeneities in terms of topological rearrangements of lipids to identify the liquid-liquid phase coexistence in model membranes. Using ideas from the physics of amorphous systems and glasses, we calculate the degree of nonaffine deformation associated with individual lipids to characterize the liquid-ordered (Lo) and liquid-disordered (Ld) regions in model lipid bilayers. We explore the usage of this method on all-atom and coarse-grained lipid bilayer trajectories. This method is helpful in defining the instantaneous Lo-Ld domain boundaries in complex multicomponent bilayer systems. The characterization is also used to highlight the effect of line-active molecules on the phase boundaries and domain mixing. Overall, we propose a framework to explore the molecular origin of spatial and dynamical heterogeneity in biomembrane systems, which can be exploited not only in computer simulations but also in experiments.
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Affiliation(s)
- Sahithya S Iyer
- Molecular Biophysics Unit, Indian Institute of Science Bangalore, Bangalore, Karnataka, India
| | - Madhusmita Tripathy
- Molecular Biophysics Unit, Indian Institute of Science Bangalore, Bangalore, Karnataka, India
| | - Anand Srivastava
- Molecular Biophysics Unit, Indian Institute of Science Bangalore, Bangalore, Karnataka, India.
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88
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Li SJ, Qian HJ, Lu ZY. A comparative study on the dynamic heterogeneity of supercooled polymers under nanoconfinement. Phys Chem Chem Phys 2019; 21:15888-15898. [PMID: 31287116 DOI: 10.1039/c9cp02550b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Dynamic heterogeneity (DH) is a universal property of glass transition phenomena. In this work, we perform a comparative analysis of DH for pure polymer and polymer/nanoparticle composite systems in both film and bulk states via molecular dynamics simulations. We find that the dynamic gradient and the faster average dynamics due to the presence of a free surface are two leading factors, resulting from a nanoconfinement effect, which influence different parts of DH in a film system. The dynamic gradient results from differences in dynamics at different distances from the mobile surface, which induces a large deviation from the Gaussian distribution for the displacement distribution in the film. At the same time, the maximum string size which describes the region size for cooperative motion (dynamic correlation) can also be influenced by the dynamic gradient, although this influence is much weaker than that on the displacement distribution. On the other hand, reflecting temporal fluctuations of dynamics or temporal parts of DH, characteristic peak times of the non-Gaussian parameter and string size, and the ratio between persistent times and exchange times which describe the dynamic exchange properties, are mainly influenced by the faster dynamics on average. Our results demonstrate that measuring different properties (dynamic distribution, dynamic correlation or dynamic exchange) place an emphasis on distinct temporal and spatial parts of DH. It is necessary to use combinational measurements of these properties to give a complete picture of DH in nanoconfinement environments.
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Affiliation(s)
- Shu-Jia Li
- State Key Laboratory of Supramolecular Structure and Materials, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130021, China.
| | - Hu-Jun Qian
- State Key Laboratory of Supramolecular Structure and Materials, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130021, China.
| | - Zhong-Yuan Lu
- State Key Laboratory of Supramolecular Structure and Materials, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130021, China.
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89
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90
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Postnikov EB. Density fluctuations and random walks in an overdamped and supercooled simple liquid. Phys Rev E 2019; 99:062117. [PMID: 31330632 DOI: 10.1103/physreve.99.062117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Indexed: 11/07/2022]
Abstract
In this work, the short-time dynamics of simple liquid is explored both analytically and numerically with the focus on the interplay between the density fluctuations in a volume surrounding a chosen particle and its random walk motion. The particles interact via the Lennard-Jones potential with parameters corresponding to liquid argon. For large times, analytical calculations based on the fluctuation theory provides an explicit expression reproducing isothermal change of the self-diffusion coefficient in liquid argon corresponding to the experimental data. These results lead to the conclusion that such behavior is based on the reduced mobility of particles reflected in their density fluctuations that can be equivalently achieved in the cases of either low temperatures and pressures (supercooling) or moderate temperatures and high pressures (overdamping).
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Affiliation(s)
- E B Postnikov
- Department of Theoretical Physics, Kursk State University, Radishcheva st., 33, 305000 Kursk, Russia
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91
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Cao CR, Huang KQ, Shi JA, Zheng DN, Wang WH, Gu L, Bai HY. Liquid-like behaviours of metallic glassy nanoparticles at room temperature. Nat Commun 2019; 10:1966. [PMID: 31036826 PMCID: PMC6488636 DOI: 10.1038/s41467-019-09895-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 04/05/2019] [Indexed: 11/09/2022] Open
Abstract
Direct atomic-scale observations and measurements on dynamics of amorphous metallic nanoparticles (a-NPs) are challenging owing to the insufficient consciousness to their striking characterizations and the difficulties in technological approaches. In this study, we observe coalescence process of the a-NPs at atomic scale. We measure the viscosity of the a-NPs through the particles coalescence by in situ method. We find that the a-NPs have fast dynamics, and the viscosity of the a-NPs exhibits a power law relationship with size of the a-NPs. The a-NPs with sizes smaller than 3 nm are in a supercooled liquid state and exhibit liquid-like behaviours with a decreased viscosity by four orders of magnitude lower than that of bulk glasses. These results reveal the intrinsic flow characteristics of glasses in low demension, and pave a way to understand the liquid-like behaviours of low dimension glass, and are also of key interest to develop size-controlled nanodevices. Nanoscale materials often exhibit size-dependent behaviour. Here, the authors use electron microscopy to quantitatively study the size-related dynamics of amorphous metallic nanoparticles, finding that particles below a critical size are in a supercooled liquid state at room temperature, with a viscosity much lower than that of bulk glasses.
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Affiliation(s)
- C R Cao
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - K Q Huang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - J A Shi
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - D N Zheng
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - W H Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.,Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - L Gu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - H Y Bai
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China. .,Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China.
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92
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Berthier L, Ozawa M, Scalliet C. Configurational entropy of glass-forming liquids. J Chem Phys 2019; 150:160902. [PMID: 31042883 DOI: 10.1063/1.5091961] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The configurational entropy is one of the most important thermodynamic quantities characterizing supercooled liquids approaching the glass transition. Despite decades of experimental, theoretical, and computational investigation, a widely accepted definition of the configurational entropy is missing, its quantitative characterization remains fraught with difficulties, misconceptions, and paradoxes, and its physical relevance is vividly debated. Motivated by recent computational progress, we offer a pedagogical perspective on the configurational entropy in glass-forming liquids. We first explain why the configurational entropy has become a key quantity to describe glassy materials, from early empirical observations to modern theoretical treatments. We explain why practical measurements necessarily require approximations that make its physical interpretation delicate. We then demonstrate that computer simulations have become an invaluable tool to obtain precise, nonambiguous, and experimentally relevant measurements of the configurational entropy. We describe a panel of available computational tools, offering for each method a critical discussion. This perspective should be useful to both experimentalists and theoreticians interested in glassy materials and complex systems.
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Affiliation(s)
- Ludovic Berthier
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | - Misaki Ozawa
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | - Camille Scalliet
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
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93
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Zou QZ, Li ZW, Zhu YL, Sun ZY. Coupling and decoupling between translational and rotational dynamics in supercooled monodisperse soft Janus particles. SOFT MATTER 2019; 15:3343-3352. [PMID: 30951070 DOI: 10.1039/c9sm00165d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We perform dynamics simulations to investigate the translational and rotational glassy dynamics in a glass-forming liquid of monodisperse soft Janus particles. We find that, with decreasing temperature, the mean-square angular displacement shows no clear plateau in the caging region, in contrast with the apparent caging behavior of translational motion. By defining a reorientational mean-square angular displacement, the caging behavior of rotational motion can be recognized. On approaching the glass transition (decreasing temperature), the coupling between translational and rotational relaxation increases, while the coupling between translational and rotational diffusion decreases, whereas the coupling between translational and reorientational diffusion increases. The strong decoupling between translational and rotational diffusion is due to the suppressed translational mobility but promoted rotational mobility of soft Janus particles. We think that the low-T SE and SED decoupling is mainly attributed to hopping motion of soft Janus particles, whereas the high-T SE and SED decoupling is mainly attributed to collective cage motion of soft Janus particles. Our results demonstrate that interaction anisotropy has a critical effect on the translational and rotational dynamics of soft Janus particles.
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Affiliation(s)
- Qing-Zhi Zou
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
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94
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Montes de Oca JM, Accordino SR, Appignanesi GA, Handle PH, Sciortino F. Size dependence of dynamic fluctuations in liquid and supercooled water. J Chem Phys 2019; 150:144505. [DOI: 10.1063/1.5085886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Joan Manuel Montes de Oca
- INQUISUR, Departamento de Química, Universidad Nacional del Sur (UNS)-CONICET, Avenida Alem 1253, 8000 Bahía Blanca, Argentina
| | - Sebastián R. Accordino
- INQUISUR, Departamento de Química, Universidad Nacional del Sur (UNS)-CONICET, Avenida Alem 1253, 8000 Bahía Blanca, Argentina
| | - Gustavo A. Appignanesi
- INQUISUR, Departamento de Química, Universidad Nacional del Sur (UNS)-CONICET, Avenida Alem 1253, 8000 Bahía Blanca, Argentina
| | - Philip H. Handle
- Department of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Francesco Sciortino
- Dipartimento di Fisica, Sapienza Universita’ di Roma, Piazzale A. Moro 5, Roma 00185, Italy
- CNR-ISC, c/o Sapienza, Piazzale A. Moro 5, Roma 00185, Italy
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95
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Pieprzyk S, Bannerman MN, Brańka AC, Chudak M, Heyes DM. Thermodynamic and dynamical properties of the hard sphere system revisited by molecular dynamics simulation. Phys Chem Chem Phys 2019; 21:6886-6899. [PMID: 30888383 DOI: 10.1039/c9cp00903e] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Revised thermodynamic and dynamical properties of the hard sphere (HS) system are obtained from extensive molecular dynamics calculations carried out with large system sizes (number of particles, N) and long times. Accurate formulas for the compressibility factor of the HS solid and fluid branches are proposed, which represent the metastable region and take into account its divergence at close packing. Some basic second-order thermodynamic properties are obtained and a maximum in some of their derivatives in the metastable fluid region is found. The thermodynamic parameters associated with the melting-freezing transition have been determined to four digit accuracy, which generates accurate new values for the coexistence properties of the HS system. For the self-diffusion coefficient, D, it is shown that relatively large systems (N > 104) are required to achieve an accurate linear extrapolation of D to the infinite size limit with a D vs. N-1/3 plot. Moreover, it is found that there is a density dependence of the value of the slope in the linear regime. The density dependent correction becomes practically insignificant at higher densities and the hydrodynamic formula found in the literature is still accurate. However, with decreasing density the density dependence of the size correction cannot be neglected, which indicates that other sources of N-dependence, apart from those derived on purely hydrodynamic grounds, may also be important (and as yet unaccounted for). A detailed analytic representation of the density dependence of the HS self-diffusion coefficient and the HS viscosity, η, is given. It is shown that the HS viscosity near freezing and in the metastable region can be described well by the Krieger-Dougherty equation. Both D and η start to scale at high densities and in the metastable region in such a way that Dηp = const, where p ≃ 0.97, and D → 0 and η → ∞ at a packing fraction of 0.58, which coincides with some previous predictions of the HS glass transition density.
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Affiliation(s)
- Sławomir Pieprzyk
- Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland.
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96
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Hoffman DJ, Fica-Contreras SM, Fayer MD. Fast dynamics of a hydrogen-bonding glass forming liquid: Chemical exchange-induced spectral diffusion in 2D IR spectroscopy. J Chem Phys 2019; 150:124507. [DOI: 10.1063/1.5088499] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- David J. Hoffman
- 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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97
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Pathak AK, Bandyopadhyay T. Temperature Induced Dynamical Transition of Biomolecules in Polarizable and Nonpolarizable TIP3P Water. J Chem Theory Comput 2019; 15:2706-2718. [PMID: 30849227 DOI: 10.1021/acs.jctc.9b00005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Temperature induced dynamical transition (DT), associated with a sharp rise in molecular flexibility, is well-known to be exhibited between 270 and 280 K in glycerol to 200-230 K in hydrated biomolecules and is controlled by diffusivity (viscosity) of the solvation layer. In the molecular dynamics (MD) community, especially for water as a solvent, this has been an intense area of research despite decades of investigations. However, in general, water in these studies is described by empirical nonpolarizable force fields in which electronic polarizability is treated implicitly with effective charges and related parameters. This might have led to the present trait of discovery that DTs of biomolecules, irrespective of the potential functions for water models used, occur within a narrow band of temperature variation (30-40 K). Whereas a water molecule in a biomolecular surface and one in bulk are polarized differently, therefore explicit treatment of water polarizability would be a powerful approach toward the treatment of hydration water, believed to cause the DT manifestation. Using MD simulations, we investigated the effects of polarizable water on the DT of biomolecules and the dynamic properties of hydration water. We chose two types of solutes: globular protein (lysozyme) and more open and flexible RNAs (a hairpin and a riboswitch) with different natures of hydrophilic sites than proteins in general. We found that the characteristic temperature of DT ( TDT) for the solutes in polarizable water is always higher than that in its nonpolarizable counterpart. In particular, for RNAs, the variations are found to be ∼45 K between the two water models, whereas for the more compact lysozyme, it is only ∼4 K. The results are discussed in light of the enormous increase in relaxation times of a liquid upon cooling in the paradigm of dynamic switchover in hydration water with liquid-liquid phase transition, derived from the existence of the second critical point. Our result supports the idea that structures of biomolecules and their interactions with the hydration water determines TDT and provides evidence for the decisive role of polarizable water on the onset of DT, which has been hitherto ignored.
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Affiliation(s)
- Arup Kumar Pathak
- Theoretical Chemistry Section , Bhabha Atomic Research Centre , Mumbai 400 085 , India.,Homi Bhabha National Institute , Mumbai 400094 , India
| | - Tusar Bandyopadhyay
- Theoretical Chemistry Section , Bhabha Atomic Research Centre , Mumbai 400 085 , India.,Homi Bhabha National Institute , Mumbai 400094 , India
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98
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Pedersen UR. Statistics of small length scale density fluctuations in supercooled viscous liquids. J Chem Phys 2019; 150:094505. [PMID: 30849876 DOI: 10.1063/1.5080277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Many successful theories of liquids near the melting temperature assume that small length scale density fluctuations follow Gaussian statistics. This paper presents a numerical investigation of density fluctuations in the supercooled viscous regime using an enhanced sampling method. Five model systems are investigated: the single component Lennard-Jones liquid, the Kob-Andersen binary mixture, the Wahnström binary mixture, the Lewis-Wahnström model of ortho-terphenyl, and the TIP4P/Ice model of water. The results show that the Gaussian approximation persists to a good degree into the supercooled viscous regime; however, it is less accurate at low temperatures. The analysis suggests that non-Gaussian fluctuations are related to crystalline configurations. Implications for theories of the glass transition are discussed.
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Affiliation(s)
- Ulf R Pedersen
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
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99
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Cubeta US, Sadtchenko V. Glass softening kinetics in the limit of high heating rates. J Chem Phys 2019; 150:094508. [DOI: 10.1063/1.5046304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ulyana S. Cubeta
- Chemistry Department, The George Washington University, Washington, District of Columbia 20052, USA
| | - Vlad Sadtchenko
- Chemistry Department, The George Washington University, Washington, District of Columbia 20052, USA
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100
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Singh A, Singh Y. Super-Arrhenius behavior of molecular glass formers. Phys Rev E 2019; 99:030101. [PMID: 30999547 DOI: 10.1103/physreve.99.030101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Indexed: 06/09/2023]
Abstract
A theory is developed to calculate values of the potential-energy barriers to structural relaxation in molecular glass formers from the data of static pair-correlation function. The barrier height is shown to increase due to an increase in the number of "stable bonds" a particle forms with its neighbors and the energy of each bond as liquids move deeper into the supercooled (supercompressed) region. We present results for a system of hard spheres and compare calculated values of the structural relaxation time with experimental and simulation results.
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Affiliation(s)
- Ankit Singh
- Department of Physics, Banaras Hindu University, Varanasi-221 005, India
| | - Yashwant Singh
- Department of Physics, Banaras Hindu University, Varanasi-221 005, India
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