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Novikov VN, Sokolov AP. Temperature Dependence of Structural Relaxation in Glass-Forming Liquids and Polymers. ENTROPY (BASEL, SWITZERLAND) 2022; 24:1101. [PMID: 36010765 PMCID: PMC9407199 DOI: 10.3390/e24081101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/05/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
Understanding the microscopic mechanism of the transition of glass remains one of the most challenging topics in Condensed Matter Physics. What controls the sharp slowing down of molecular motion upon approaching the glass transition temperature Tg, whether there is an underlying thermodynamic transition at some finite temperature below Tg, what the role of cooperativity and heterogeneity are, and many other questions continue to be topics of active discussions. This review focuses on the mechanisms that control the steepness of the temperature dependence of structural relaxation (fragility) in glass-forming liquids. We present a brief overview of the basic theoretical models and their experimental tests, analyzing their predictions for fragility and emphasizing the successes and failures of the models. Special attention is focused on the connection of fast dynamics on picosecond time scales to the behavior of structural relaxation on much longer time scales. A separate section discusses the specific case of polymeric glass-forming liquids, which usually have extremely high fragility. We emphasize the apparent difference between the glass transitions in polymers and small molecules. We also discuss the possible role of quantum effects in the glass transition of light molecules and highlight the recent discovery of the unusually low fragility of water. At the end, we formulate the major challenges and questions remaining in this field.
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Affiliation(s)
- Vladimir N. Novikov
- Institute of Automation and Electrometry, Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Alexei P. Sokolov
- Department of Chemistry and Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, TN 37996, USA
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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2
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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: 7] [Impact Index Per Article: 1.8] [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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Agapov AL, Novikov VN, Hong T, Fan F, Sokolov AP. Surprising Temperature Scaling of Viscoelastic Properties in Polymers. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00454] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alexander L. Agapov
- Department of Chemistry, University of Tennessee, 1420 Circle Drive, Knoxville, Tennessee 37996, United States
| | - Vladimir N. Novikov
- Department of Chemistry, University of Tennessee, 1420 Circle Drive, Knoxville, Tennessee 37996, United States
- Institute of Automation and Electrometry, Russian Academy of Sciences, 1 Koptyug ave., Novosibirsk 630090, Russia
| | - Tao Hong
- Department of Chemistry, University of Tennessee, 1420 Circle Drive, Knoxville, Tennessee 37996, United States
| | - Fei Fan
- Department of Chemistry, University of Tennessee, 1420 Circle Drive, Knoxville, Tennessee 37996, United States
| | - Alexei P. Sokolov
- Department of Chemistry, University of Tennessee, 1420 Circle Drive, Knoxville, Tennessee 37996, United States
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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Zulli F, Giordano M, Andreozzi L. Chain-Length Dependence of Relaxation and Dynamics in Poly(methyl methacrylate) from Oligomers to Polymers. Macromolecules 2018. [DOI: 10.1021/acs.macromol.7b02330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Fabio Zulli
- Department of Physics “E. Fermi”, University of Pisa and IPCF-CNR, Pisa, Italy
| | - Marco Giordano
- Department of Physics “E. Fermi”, University of Pisa and IPCF-CNR, Pisa, Italy
| | - Laura Andreozzi
- Department of Physics “E. Fermi”, University of Pisa and IPCF-CNR, Pisa, Italy
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Ballner D, Herzele S, Keckes J, Edler M, Griesser T, Saake B, Liebner F, Potthast A, Paulik C, Gindl-Altmutter W. Lignocellulose Nanofiber-Reinforced Polystyrene Produced from Composite Microspheres Obtained in Suspension Polymerization Shows Superior Mechanical Performance. ACS APPLIED MATERIALS & INTERFACES 2016; 8:13520-5. [PMID: 27163488 DOI: 10.1021/acsami.6b01992] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A facile approach to obtaining cellulose nanofiber-reinforced polystyrene with greatly improved mechanical performance compared to unreinforced polystyrene is presented. Cellulose nanofibers were obtained by mechanical fibrillation of partially delignified wood (MFLC) and compared to nanofibers obtained from bleached pulp. Residual hemicellulose and lignin imparted amphiphilic surface chemical character to MFLC, which enabled the stabilization of emulsions of styrene in water. Upon suspension polymerization of styrene from the emulsion, polystyrene microspheres coated in MFLC were obtained. When processed into polymer sheets by hot-pressing, improved bending strength and superior impact toughness was observed for the polystyrene-MFLC composite compared to the un-reinforced polystyrene.
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Affiliation(s)
| | - Sabine Herzele
- Kompetenzzentrum Holz GmbH , Altenbergerstrasse 69, 4040 Linz, Austria
| | - Jozef Keckes
- Department of Materials Physics, University of Leoben , Jahnstrasse 12, 8700 Leoben, Austria
| | - Matthias Edler
- Department of Polymer Technology, University of Leoben , Otto Glöckel Strasse 2, 8700 Leoben, Austria
| | - Thomas Griesser
- Department of Polymer Technology, University of Leoben , Otto Glöckel Strasse 2, 8700 Leoben, Austria
| | - Bodo Saake
- Zentrum Holzwirtschaft, University of Hamburg , Leuschnerstrasse 91, 21031 Hamburg-Bergedorf, Germany
| | | | | | - Christian Paulik
- Institute for Chemical Technology of Organic Materials, Johannes Kepler University , Altenbergerstrasse 69, 4040 Linz, Austria
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Dudowicz J, Douglas JF, Freed KF. The meaning of the "universal" WLF parameters of glass-forming polymer liquids. J Chem Phys 2015; 142:014905. [PMID: 25573581 DOI: 10.1063/1.4905216] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Although the Williams-Landell-Ferry (WLF) equation for the segmental relaxation time τ(T) of glass-forming materials is one of the most commonly encountered relations in polymer physics, its molecular basis is not well understood. The WLF equation is often claimed to be equivalent to the Vogel-Fulcher-Tammann (VFT) equation, even though the WLF expression for τ(T) contains no explicit dependence on the fragility parameter D of the VFT equation, while the VFT equation lacks any explicit reference to the glass transition temperature Tg, the traditionally chosen reference temperature in the WLF equation. The observed approximate universality of the WLF parameters C1((g)) and C2((g)) implies that τ(T) depends only on T-Tg, a conclusion that seems difficult to reconcile with the VFT equation where the fragility parameter D largely governs the magnitude of τ(T). The current paper addresses these apparent inconsistencies by first evaluating the macroscopic WLF parameters C1((g)) and C2((g)) from the generalized entropy theory of glass-formation and then by determining the dependence of C1((g)) and C2((g)) on the microscopic molecular parameters (including the strength of the cohesive molecular interactions and the degree of chain stiffness) and on the molar mass of the polymer. Attention in these calculations is restricted to the temperature range (Tg < T < Tg + 100 K), where both the WLF and VFT equations apply.
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Affiliation(s)
- Jacek Dudowicz
- The James Franck Institute and the Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Karl F Freed
- The James Franck Institute and the Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA
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Correlation between fragility and cooperativity in segmental dynamics of glass-forming para-substituted polystyrenes. Polym J 2015. [DOI: 10.1038/pj.2015.50] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Mora E, Brás AR, Pyckhout-Hintzen W, Diogo HP, Moura Ramos JJ. The segmental and chain relaxation modes in high-cis-polyisoprene as studied by thermally stimulated currents. J Chem Phys 2015; 142:044903. [PMID: 25638005 DOI: 10.1063/1.4906542] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The technique of Thermally Stimulated Currents is used to study the slow molecular mobility in a series of poly (1,4-cis-isoprene) samples with different molecular weights, Mw, and low polydispersity. The technique revealed a high resolution power, particularly useful in the study of the lower molecular weight samples where the chain and the segmental relaxations strongly overlap. The dynamic crossover that is reported for the normal mode by varying the molecular weight is clearly revealed by the thermally stimulated depolarization currents results through the temperature location, TMn, of the normal mode peak, the values of the relaxation time at TMn, τ(TMn), and the value of the fragility index of the normal mode, mn. The kinetic features of the glass transition relaxation of polyisoprene have also been determined.
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Affiliation(s)
- Elsa Mora
- CQE-Centro de Química Estrutural, Universidade de Lisboa, Complexo I, IST, 1049-001 Lisboa, Portugal
| | - Ana R Brás
- Jülich Centre for Neutron Science and Institute for Complex Systems, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Wim Pyckhout-Hintzen
- Jülich Centre for Neutron Science and Institute for Complex Systems, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Hermínio P Diogo
- CQE-Centro de Química Estrutural, Universidade de Lisboa, Complexo I, IST, 1049-001 Lisboa, Portugal
| | - Joaquim J Moura Ramos
- CQFM-Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
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Hofmann M, Herrmann A, Abou Elfadl A, Kruk D, Wohlfahrt M, Rössler EA. Glassy, Rouse, and Entanglement Dynamics As Revealed by Field Cycling 1H NMR Relaxometry. Macromolecules 2012. [DOI: 10.1021/ma202371p] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Hofmann
- Experimentalphysik
II, Universität Bayreuth, D-95440
Bayreuth, Germany
| | - A. Herrmann
- Experimentalphysik
II, Universität Bayreuth, D-95440
Bayreuth, Germany
| | - A. Abou Elfadl
- Experimentalphysik
II, Universität Bayreuth, D-95440
Bayreuth, Germany
| | - D. Kruk
- University of Warmia & Mazury Olsztyn, Faculty of Mathematics & Computer Science, Sloneczna 54, PL-10710 Olsztyn, Poland
| | - M. Wohlfahrt
- Experimentalphysik
II, Universität Bayreuth, D-95440
Bayreuth, Germany
| | - E. A. Rössler
- Experimentalphysik
II, Universität Bayreuth, D-95440
Bayreuth, Germany
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Eremchev IY, Vainer YG, Naumov AV, Kador L. Low-temperature dynamics in amorphous polymers and low-molecular-weight glasses--what is the difference? Phys Chem Chem Phys 2010; 13:1843-8. [PMID: 21183979 DOI: 10.1039/c0cp01690j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Numerous experiments have shown that the low-temperature dynamics of a wide variety of disordered solids is qualitatively universal. However, most of these results were obtained with ensemble-averaging techniques which hide the local parameters of the dynamic processes. We used single-molecule (SM) spectroscopy for direct observation of the dynamic processes in disordered solids with different internal structure and chemical composition. The surprising result is that the dynamics of low-molecular-weight glasses and short-chain polymers does not follow, on a microscopic level, the current concept of low-temperature glass dynamics. An extra contribution to the dynamics was detected causing irreproducible jumps and drifts of the SM spectra on timescales between milliseconds and minutes. In most matrices consisting of small molecules and oligomers, the spectral dynamics was so fast that SM spectra could hardly or not at all be recorded and only irregular fluorescence flares were observed. These results provide new mechanistic insight into the behavior of glasses in general: At low temperatures, the local dynamics of disordered solids is not universal but depends on the structure and chemical composition of the material.
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Affiliation(s)
- Ivan Yu Eremchev
- Molecular Spectroscopy Department, Institute for Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow reg., 142190, Russia
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Bormuth A, Henritzi P, Vogel M. Chain-Length Dependence of the Segmental Relaxation in Polymer Melts: Molecular Dynamics Simulation Studies on Poly(propylene oxide). Macromolecules 2010. [DOI: 10.1021/ma101721d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Bormuth
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - P. Henritzi
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - M. Vogel
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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12
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Dalle-Ferrier C, Niss K, Sokolov AP, Frick B, Serrano J, Alba-Simionesco C. The Role of Chain Length in Nonergodicity Factor and Fragility of Polymers. Macromolecules 2010. [DOI: 10.1021/ma101622f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Cécile Dalle-Ferrier
- Laboratoire de Chimie Physique, Bâtiment 349, Université Paris-Sud, 91405 Orsay, France. Current address: Soft Matter group, IPkM, Heinrich Heine Universität, Düsseldorf, Germany
| | - Kristine Niss
- Laboratoire de Chimie Physique, Bâtiment 349, Université Paris-Sud, 91405 Orsay, France. Current address: Glass and Time, IMFUFA, Department of Sciences, Building 27 Roskilde University RUC Postbox 260 DK-4000 Roskilde, Denmark
| | - Alexei P. Sokolov
- Chemical Sciences Division at ORNL, Oak Ridge; and Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | | | - Jorge Serrano
- ICREA-Departament de Física Aplicada, EPSC, Universitat Politècnica de Catalunya, Esteve Terradas 15, 08860 Castelldefels, Spain
| | - Christiane Alba-Simionesco
- Laboratoire de Chimie Physique, Bâtiment 349, Université Paris-Sud, 91405 Orsay, France. Current address: Laboratoire Léon Brillouin, CEA-CNRS, Saclay, France
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Abou Elfadl A, Kahlau R, Herrmann A, Novikov VN, Rössler EA. From Rouse to Fully Established Entanglement Dynamics: A Study of Polyisoprene by Dielectric Spectroscopy. Macromolecules 2010. [DOI: 10.1021/ma902564b] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. Abou Elfadl
- Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth, Germany
| | - R. Kahlau
- Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth, Germany
| | - A. Herrmann
- Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth, Germany
| | - V. N. Novikov
- IA&E, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - E. A. Rössler
- Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth, Germany
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