1
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Böhmer T, Pabst F, Gabriel JP, Blochowicz T. Dipolar Order Controls Dielectric Response of Glass-Forming Liquids. PHYSICAL REVIEW LETTERS 2024; 132:206101. [PMID: 38829064 DOI: 10.1103/physrevlett.132.206101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 11/15/2023] [Accepted: 04/09/2024] [Indexed: 06/05/2024]
Abstract
The dielectric response of liquids reflects both reorientation of single molecular dipoles and collective modes, i.e., dipolar cross-correlations. A recent theory predicts the latter to produce an additional slow peak in the dielectric loss spectrum. Following this idea we argue that in supercooled liquids the high-frequency power law exponent of the dielectric loss β should be correlated with the degree of dipolar order, i.e., the Kirkwood correlation factor g_{K}. This notion is confirmed for 25 supercooled liquids. While our findings support recent theoretical work the results are shown to violate the earlier Kivelson-Madden theory.
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Affiliation(s)
- Till Böhmer
- Institute for Condensed Matter Physics, Technical University of Darmstadt, D-64289 Darmstadt, Germany
| | - Florian Pabst
- Institute for Condensed Matter Physics, Technical University of Darmstadt, D-64289 Darmstadt, Germany
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Jan P Gabriel
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, Post Office Box 260, DK-4000 Roskilde, Denmark
- Institute of Material Physics in Space, German Aerospace Center, 51147 Cologne, Germany
| | - Thomas Blochowicz
- Institute for Condensed Matter Physics, Technical University of Darmstadt, D-64289 Darmstadt, Germany
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2
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Pinheiro Dos Santos TJ, Orcan-Ekmekci B, Chapman WG, Singer PM, Asthagiri DN. Theory and modeling of molecular modes in the NMR relaxation of fluids. J Chem Phys 2024; 160:064108. [PMID: 38341792 DOI: 10.1063/5.0180040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 01/18/2024] [Indexed: 02/13/2024] Open
Abstract
Traditional theories of the nuclear magnetic resonance (NMR) autocorrelation function for intra-molecular dipole pairs assume a single-exponential decay, yet the calculated autocorrelation of realistic systems displays a rich, multi-exponential behavior, resulting in anomalous NMR relaxation dispersion (i.e., frequency dependence). We develop an approach to model and interpret the multi-exponential intra-molecular autocorrelation using simple, physical models within a rigorous statistical mechanical development that encompasses both rotational diffusion and translational diffusion in the same framework. We recast the problem of evaluating the autocorrelation in terms of averaging over a diffusion propagator whose evolution is described by a Fokker-Planck equation. The time-independent part admits an eigenfunction expansion, allowing us to write the propagator as a sum over modes. Each mode has a spatial part that depends on the specified eigenfunction and a temporal part that depends on the corresponding eigenvalue (i.e., correlation time) with a simple, exponential decay. The spatial part is a probability distribution of the dipole pair, analogous to the stationary states of a quantum harmonic oscillator. Drawing inspiration from the idea of inherent structures in liquids, we interpret each of the spatial contributions as a specific molecular mode. These modes can be used to model and predict the NMR dipole-dipole relaxation dispersion of fluids by incorporating phenomena on the molecular level. We validate our statistical mechanical description of the distribution in molecular modes with molecular dynamics simulations interpreted without any relaxation models or adjustable parameters: the most important poles in the Padé-Laplace transform of the simulated autocorrelation agree with the eigenvalues predicted by the theory.
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Affiliation(s)
| | | | - Walter G Chapman
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
| | - Philip M Singer
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
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3
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Winterstein S, Privalov AF, Greve C, Siegel R, Pötzschner B, Bettermann M, Adolph L, Timm J, Marschall R, Rössler EA, Herzig EM, Vogel M, Senker J. Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework. J Am Chem Soc 2023; 145:27563-27575. [PMID: 38060438 PMCID: PMC10740000 DOI: 10.1021/jacs.3c09257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 11/12/2023] [Accepted: 11/20/2023] [Indexed: 12/21/2023]
Abstract
Sulfonated, cross-linked porous polymers are promising frameworks for aqueous high-performance electrolyte-host systems for electrochemical energy storage and conversion. The systems offer high proton conductivities, excellent chemical and mechanical stabilities, and straightforward water management. However, little is known about mass transport mechanisms in such nanostructured hosts. We report on the synthesis and postsynthetic sulfonation of an aromatic framework (SPAF-2) with a 3D-interconnected nanoporosity and varying sulfonation degrees. Water adsorption produces the system SPAF-2H20. It features proton exchange capacities up to 6 mequiv g-1 and exceptional proton conductivities of about 1 S cm-1. Two contributions are essential for the highly efficient transport. First, the nanometer-sized pores link the charge transport to the diffusion of adsorbed water molecules, which is almost as fast as bulk water. Second, continuous exchange between interface-bound and mobile species enhances the conductivities at elevated temperatures. SPAF-2H20 showcases how to tailor nanostructured electrolyte-host systems with liquid-like conductivities.
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Affiliation(s)
- Simon
F. Winterstein
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Alexei F. Privalov
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Christopher Greve
- Dynamics
and Structure Formation, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Renée Siegel
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Björn Pötzschner
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Michael Bettermann
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Lea Adolph
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Jana Timm
- Physical
Chemistry III, Department of Chemistry, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Roland Marschall
- Physical
Chemistry III, Department of Chemistry, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Ernst A. Rössler
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Eva M. Herzig
- Dynamics
and Structure Formation, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Michael Vogel
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Jürgen Senker
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
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4
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Hénot M, Déjardin PM, Ladieu F. Orientational dynamics in supercooled glycerol computed from MD simulations: self and cross contributions. Phys Chem Chem Phys 2023; 25:29233-29240. [PMID: 37873650 DOI: 10.1039/d3cp04578a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The orientational dynamics of supercooled glycerol is probed using molecular dynamics simulations for temperatures ranging from 323 K to 253 K, through correlation functions of first and second ranks of Legendre polynomials, pertaining respectively to dielectric spectroscopy (DS) and depolarized dynamic light scattering (DDLS). The self, cross, and total correlation functions are compared with relevant experimental data. The computations reveal the low sensitivity of DDLS to cross-correlations, in agreement with what is found in experimental work, and strengthen the idea of directly comparing DS and DDLS data to evaluate the effect of cross-correlations in polar liquids. The analysis of the net static cross-correlations and their spatial decomposition shows that, although cross-correlations extend over nanometric distances, their net magnitude originates, in the case of glycerol, from the first shell of neighbouring molecules. Accessing the angular dependence of the static correlation allows us to get a microscopic understanding of why the rank-1 correlation function is more sensitive to cross-correlation than its rank-2 counterpart.
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Affiliation(s)
- Marceau Hénot
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay Bat 772, 91191 Gif-sur-Yvette Cedex, France.
| | - Pierre-Michel Déjardin
- Laboratoire de Modélisation Pluridisciplinaire et Simulations, Université de Perpignan Via Domitia, 52 avenue Paul Alduy, F-66860 Perpignan, France
| | - François Ladieu
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay Bat 772, 91191 Gif-sur-Yvette Cedex, France.
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5
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Gravelle S, Haber-Pohlmeier S, Mattea C, Stapf S, Holm C, Schlaich A. NMR Investigation of Water in Salt Crusts: Insights from Experiments and Molecular Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37207369 DOI: 10.1021/acs.langmuir.3c00036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The evaporation of water from bare soil is often accompanied by the formation of a layer of crystallized salt, a process that must be understood in order to address the issue of soil salinization. Here, we use nuclear magnetic relaxation dispersion measurements to better understand the dynamic properties of water within two types of salt crusts: sodium chloride (NaCl) and sodium sulfate (Na2SO4). Our experimental results display a stronger dispersion of the relaxation time T1 with frequency for the case of sodium sulfate as compared to sodium chloride salt crusts. To gain insight into these results, we perform molecular dynamics simulations of salt solutions confined within slit nanopores made of either NaCl or Na2SO4. We find a strong dependence of the value of the relaxation time T1 on pore size and salt concentration. Our simulations reveal the complex interplay between the adsorption of ions at the solid surface, the structure of water near the interface, and the dispersion of T1 at low frequency, which we attribute to adsorption-desorption events.
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Affiliation(s)
- Simon Gravelle
- Institute for Computational Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Sabina Haber-Pohlmeier
- Institut für Wasser und Umweltsystemmodellierung, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Carlos Mattea
- Institute of Physics, Technische Universität Ilmenau, Ilmenau 98693, Germany
| | - Siegfried Stapf
- Institute of Physics, Technische Universität Ilmenau, Ilmenau 98693, Germany
| | - Christian Holm
- Institute for Computational Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Alexander Schlaich
- Institute for Computational Physics, University of Stuttgart, D-70569 Stuttgart, Germany
- Stuttgart Center for Simulation Science (SC SimTech), University of Stuttgart, 70569 Stuttgart, Germany
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6
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Beckmann JBB, Rauber D, Philippi F, Goloviznina K, Ward-Williams JA, Sederman AJ, Mantle MD, Pádua A, Kay CWM, Welton T, Gladden LF. Molecular Dynamics of Ionic Liquids from Fast-Field Cycling NMR and Molecular Dynamics Simulations. J Phys Chem B 2022; 126:7143-7158. [PMID: 36094902 PMCID: PMC9511496 DOI: 10.1021/acs.jpcb.2c01372] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Understanding the connection between the molecular structure
of
ionic liquids and their properties is of paramount importance for
practical applications. However, this connection can only be established
if a broad range of physicochemical properties on different length
and time scales is already available. Even then, the interpretation
of the results often remains ambiguous due to the natural limits of
experimental approaches. Here we use fast-field cycling (FFC) to access
both translational and rotational dynamics of ionic liquids. These
combined with a comprehensive physicochemical characterization and
MD simulations provide a toolkit to give insight into the mechanisms
of molecular mechanics. The FFC results are consistent with the computer
simulation and conventional physicochemical approaches. We show that
curling of the side chains around the positively charged cationic
core is essential for the properties of ether-functionalized ionic
liquids, and we demonstrate that neither geometry nor polarity alone
are sufficient to explain the macroscopic properties.
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Affiliation(s)
- Julian B B Beckmann
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
| | - Daniel Rauber
- Department of Chemistry, Saarland University, Campus B2.2, 66123 Saarbrücken, Germany
| | - Frederik Philippi
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, United Kingdom
| | - Kateryna Goloviznina
- Laboratoire de Chimie, École Normale Supérieure de Lyon & CNRS, 69364 Lyon, France
| | - Jordan A Ward-Williams
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
| | - Andy J Sederman
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
| | - Mick D Mantle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
| | - Agílio Pádua
- Laboratoire de Chimie, École Normale Supérieure de Lyon & CNRS, 69364 Lyon, France
| | - Christopher W M Kay
- Department of Chemistry, Saarland University, Campus B2.2, 66123 Saarbrücken, Germany.,London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
| | - Tom Welton
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, United Kingdom
| | - Lynn F Gladden
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
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7
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Böhmer T, Gabriel JP, Zeißler R, Richter T, Blochowicz T. Glassy dynamics in polyalcohols: intermolecular simplicity vs. intramolecular complexity. Phys Chem Chem Phys 2022; 24:18272-18280. [PMID: 35880532 DOI: 10.1039/d2cp01969h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using depolarized light scattering, we have recently shown that structural relaxation in a broad range of supercooled liquids follows, to good approximation, a generic line shape with high-frequency power law ω-1/2. We now continue this study by investigating a systematic series of polyalcohols (PAs), frequently used as model-systems in glass-science, i.a., because the width of their respective dielectric loss spectra varies strongly along the series. Our results reveal that the microscopic origin of the observed relaxation behavior varies significantly between different PAs: while short-chained PAs like glycerol rotate as more or less rigid entities and their light scattering spectra follow the generic shape, long-chained PAs like sorbitol display pronounced intramolecular dynamic contributions on the time scale of structural relaxation, leading to systematic deviations from the generic shape. Based on these findings we discuss an important limitation for observing the generic shape in a supercooled liquid: the dynamics that is probed needs to reflect the intermolecular dynamic heterogeneity, and must not be superimposed by effects of intramolecular dynamic heterogeneity.
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Affiliation(s)
- Till Böhmer
- Institute for Condensed Matter Physics, Technical University Darmstadt, Darmstadt, Germany.
| | - Jan Philipp Gabriel
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Rolf Zeißler
- Institute for Condensed Matter Physics, Technical University Darmstadt, Darmstadt, Germany.
| | - Timo Richter
- Institute for Condensed Matter Physics, Technical University Darmstadt, Darmstadt, Germany.
| | - Thomas Blochowicz
- Institute for Condensed Matter Physics, Technical University Darmstadt, Darmstadt, Germany.
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8
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Becher M, Horstmann R, Kloth S, Rössler EA, Vogel M. A Relation between the Formation of a Hydrogen-Bond Network and a Time-Scale Separation of Translation and Rotation in Molecular Liquids. J Phys Chem Lett 2022; 13:4556-4562. [PMID: 35580032 DOI: 10.1021/acs.jpclett.2c00821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We study the relation between the translational and rotational motions of liquids, which is anticipated in the framework of the Stokes-Einstein-Debye (SED) treatment. For this purpose, we exploit the fact that 1H field-cycling nuclear magnetic resonance relaxometry and molecular dynamics simulations provide access to both modes of motion. The experimental and computational findings are fully consistent and show that the time-scale separation between translation and rotation increases from the van der Waals liquid o-terphenyl over ethylene glycol to the hydrogen-bonded liquid glycerol, indicating an increasing degree of breakdown of the SED relation. Furthermore, the simulation results for two ethylene glycol models with different molecular conformations indicate that the translation is more retarded than the rotation when the density of intermolecular hydrogen bonds increases. We conclude that an increasing connectivity of a hydrogen-bond network leads to an increasing time-scale separation and, thus, to a stronger SED violation.
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Affiliation(s)
- Manuel Becher
- Anorganische Chemie 3, Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Robin Horstmann
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Sebastian Kloth
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Ernst A Rössler
- Anorganische Chemie 3, Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Michael Vogel
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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9
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Becher M, Lichtinger A, Minikejew R, Vogel M, Rössler EA. NMR Relaxometry Accessing the Relaxation Spectrum in Molecular Glass Formers. Int J Mol Sci 2022; 23:ijms23095118. [PMID: 35563506 PMCID: PMC9105706 DOI: 10.3390/ijms23095118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 12/10/2022] Open
Abstract
It is a longstanding question whether universality or specificity characterize the molecular dynamics underlying the glass transition of liquids. In particular, there is an ongoing debate to what degree the shape of dynamical susceptibilities is common to various molecular glass formers. Traditionally, results from dielectric spectroscopy and light scattering have dominated the discussion. Here, we show that nuclear magnetic resonance (NMR), primarily field-cycling relaxometry, has evolved into a valuable method, which provides access to both translational and rotational motions, depending on the probe nucleus. A comparison of 1H NMR results indicates that translation is more retarded with respect to rotation for liquids with fully established hydrogen-bond networks; however, the effect is not related to the slow Debye process of, for example, monohydroxy alcohols. As for the reorientation dynamics, the NMR susceptibilities of the structural (α) relaxation usually resemble those of light scattering, while the dielectric spectra of especially polar liquids have a different broadening, likely due to contributions from cross correlations between different molecules. Moreover, NMR relaxometry confirms that the excess wing on the high-frequency flank of the α-process is a generic relaxation feature of liquids approaching the glass transition. However, the relevance of this feature generally differs between various methods, possibly because of their different sensitivities to small-amplitude motions. As a major advantage, NMR is isotope specific; hence, it enables selective studies on a particular molecular entity or a particular component of a liquid mixture. Exploiting these possibilities, we show that the characteristic Cole-Davidson shape of the α-relaxation is retained in various ionic liquids and salt solutions, but the width parameter may differ for the components. In contrast, the low-frequency flank of the α-relaxation can be notably broadened for liquids in nanoscopic confinements. This effect also occurs in liquid mixtures with a prominent dynamical disparity in their components.
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Affiliation(s)
- Manuel Becher
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
| | - Anne Lichtinger
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
| | - Rafael Minikejew
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
| | - Michael Vogel
- Institut für Physik Kondensierter Materie, Technische Universität Darmstadt, 64289 Darmstadt, Germany;
| | - Ernst A. Rössler
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
- Correspondence:
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10
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Becher M, Flämig M, Rössler EA. Field-cycling 31P and 1H NMR relaxometry studying the reorientational dynamics of glass forming organophosphates. J Chem Phys 2022; 156:074502. [DOI: 10.1063/5.0082566] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- M. Becher
- Nordbayerisches NMR-Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - M. Flämig
- Nordbayerisches NMR-Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - E. A. Rössler
- Nordbayerisches NMR-Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
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11
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Vijayakumar B, Takatsuka M, Kita R, Shinyashiki N, Yagihara S, Rathinasabapathy S. Dynamics of the Poly(N-Isopropylacrylamide) Microgel Aqueous Suspension Investigated by Dielectric Relaxation Spectroscopy. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Balachandar Vijayakumar
- Department of Physics, Sathyabama Institute of Science and Technology, Chennai 600119, India
| | - Masanobu Takatsuka
- Graduate School of Science and Technology, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
| | - Rio Kita
- Department of Physics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
- Micro/Nano Technology Center, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
| | - Naoki Shinyashiki
- Department of Physics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
- Micro/Nano Technology Center, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
| | - Shin Yagihara
- Department of Physics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
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12
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Fraenza CC, Elgammal RA, Garaga MN, Bhattacharyya S, Zawodzinski TA, Greenbaum SG. Dynamics of Glyceline and Interactions of Constituents: A Multitechnique NMR Study. J Phys Chem B 2022; 126:890-905. [DOI: 10.1021/acs.jpcb.1c09227] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Carla C. Fraenza
- Department of Physics and Astronomy, Hunter College of CUNY, New York, New York 10065, United States
| | - Ramez A. Elgammal
- Department of Chemical and Biomolecular Engineering, University of Tennessee-Knoxville, Knoxville, Tennessee 37996, United States
| | - Mounesha N. Garaga
- Department of Physics and Astronomy, Hunter College of CUNY, New York, New York 10065, United States
| | - Sahana Bhattacharyya
- Department of Physics and Astronomy, Hunter College of CUNY, New York, New York 10065, United States
| | - Thomas A. Zawodzinski
- Department of Chemical and Biomolecular Engineering, University of Tennessee-Knoxville, Knoxville, Tennessee 37996, United States
| | - Steven G. Greenbaum
- Department of Physics and Astronomy, Hunter College of CUNY, New York, New York 10065, United States
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13
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Becher M, Körber T, Döß A, Hinze G, Gainaru C, Böhmer R, Vogel M, Rössler EA. Nuclear Spin Relaxation in Viscous Liquids: Relaxation Stretching of Single-Particle Probes. J Phys Chem B 2021; 125:13519-13532. [PMID: 34860530 DOI: 10.1021/acs.jpcb.1c06722] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spin-lattice relaxation rates R1(ω,T), probed via high-field and field-cycling nuclear magnetic resonance (NMR), are used to test the validity of frequency-temperature superposition (FTS) for the reorientation dynamics in viscous liquids. For several liquids, FTS is found to apply so that master curves can be generated. The susceptibility spectra are highly similar to those obtained from depolarized light scattering (DLS) and reveal an excess wing. Where FTS works, two approaches are suggested to access the susceptibility: (i) a plot of deuteron R1(T) vs the spin-spin relaxation rate R2(T) and (ii) a plot of R1(T) vs an independently measured reference time τref(T). Using single-frequency scans, (i) allows one to extract the relaxation stretching as well as the NMR coupling constant. Surveying 26 data sets, we find Kohlrausch functions with exponents 0.39 < βK ≤ 0.67. Plots of the spin-spin relaxation rate R2─rescaled by the NMR coupling constant─as a function of temperature allow one to test how well site-specific NMR relaxations couple to a given reference process. Upon cooling of flexible molecule liquids, the site-specific dynamics is found to merge, suggesting that near Tg the molecules reorient essentially as a rigid entity. This presents a possible resolution for the much lower stretching parameters reported here at high temperatures that contrast with the ones that were reported to be universal in a recent DLS study close to Tg. Our analysis underlines that deuteron relaxation is a uniquely powerful tool to probe single-particle reorientation.
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Affiliation(s)
- M Becher
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Th Körber
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - A Döß
- Department Chemie, Johannes Gutenberg-Universität, 55128 Mainz, Germany
| | - G Hinze
- Department Chemie, Johannes Gutenberg-Universität, 55128 Mainz, Germany
| | - C Gainaru
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - R Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - M Vogel
- Institut für Physik kondensierter Materie, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - E A Rössler
- Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
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Bhatt S, Bagchi D. Molecular and micro-scale heterogeneities in Raman modes of a relaxing polymer glass. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:325101. [PMID: 34062521 DOI: 10.1088/1361-648x/ac06ec] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/01/2021] [Indexed: 06/12/2023]
Abstract
We have used Raman spectroscopy to study relaxation dynamics at two different length scales, molecular level and micro-scale in order to probe the presence of cooperative rearranging regions in a polymer glass. Response to slow thermal cycles and fast quench through the glass transition temperature (Tg) is analyzed for film and unprocessed forms of polyvinyl acetate (PVAc). In PVAc film, enhanced disorder and molecular mobility lead to peak broadening by about a factor of 10 compared to unprocessed PVAc. Thermal cycles (10 K min-1) produce hysteresis in integrated Raman peak intensity (loop areaAINTI).AINTIvalues of film are two orders of magnitude more than unprocessed, indicating more configurational mosaics with higher interfacial energy dissipations. Ageing after 60 K min-1quench manifests as heterogeneous molecular dynamics of film Raman modes with significant peak-width variations, differentiating high mobility and low mobility modes. Two-dimensional mapping of film Raman modes after quench reveal micro-scale clusters of average size ≈250 molecules having fractal boundaries with fractal dimensiondf= 1.5, resemblingdfof percolation clusters below percolation threshold. During thermal cycling and relaxation after a quench, cooperative segmental dynamics with large correlations between skeletal C-C stretch and side branch modes is observed. The observations are analyzed in the context of the random first order transition theory of glasses, which attributes heterogeneous relaxations in glasses to the presence of clusters of variable configurational states.
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Affiliation(s)
- Shipra Bhatt
- Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390002, Gujarat, India
| | - Debjani Bagchi
- Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390002, Gujarat, India
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