1
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Lee Y, Cheng S, Ediger MD. High Density Two-Component Glasses of Organic Semiconductors Prepared by Physical Vapor Deposition. J Phys Chem Lett 2024:8085-8092. [PMID: 39087749 DOI: 10.1021/acs.jpclett.4c01508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
Physical vapor deposition (PVD) is widely utilized for the production of organic semiconductor devices due to its ability to form thin layers with exceptional properties. Although the layers in the device usually consist of two or more components, there is limited understanding about the fundamental characteristics of such multicomponent vapor-deposited glasses. Here, spectroscopic ellipsometry was employed to characterize the densities, thermal stabilities, and optical properties of covapor deposited NPD and TPD glasses across the entire range of composition. We find that codeposited NPD and TPD form high density glasses with enhanced thermal stability. The dependences of density and stability upon substrate temperature are correlated, and the birefringence of the codeposited glasses is determined by the reduced substrate temperature of mixtures. Additionally, we observe that the transformation of a highly stable and dense two-component glass into its supercooled liquid initiates from the free surface and propagates into the bulk at a constant velocity, like single component PVD glasses. All of these features are consistent with the surface equilibration mechanism.
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Affiliation(s)
- Yejung Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Shinian Cheng
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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2
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Herrero C, Berthier L. Direct Numerical Analysis of Dynamic Facilitation in Glass-Forming Liquids. PHYSICAL REVIEW LETTERS 2024; 132:258201. [PMID: 38996241 DOI: 10.1103/physrevlett.132.258201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 05/21/2024] [Indexed: 07/14/2024]
Abstract
We propose a computational strategy to quantify the temperature evolution of the timescales and length scales over which dynamic facilitation affects the relaxation dynamics of glass-forming liquids at low temperatures, which requires no assumption about the nature of the dynamics. In two glass models, we find that dynamic facilitation depends strongly on temperature, leading to a subdiffusive spreading of relaxation events which we characterize using a temperature-dependent dynamic exponent. We also establish that this temperature evolution represents a major contribution to the increase of the structural relaxation time.
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3
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Herrero C, Ediger MD, Berthier L. Front propagation in ultrastable glasses is dynamically heterogeneous. J Chem Phys 2023; 159:114504. [PMID: 37724735 DOI: 10.1063/5.0168506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 08/31/2023] [Indexed: 09/21/2023] Open
Abstract
Upon heating, ultrastable glassy films transform into liquids via a propagating equilibration front, resembling the heterogeneous melting of crystals. A microscopic understanding of this robust phenomenology is, however, lacking because experimental resolution is limited. We simulate the heterogeneous transformation kinetics of ultrastable configurations prepared using the swap Monte Carlo algorithm, thus allowing a direct comparison with experiments. We resolve the liquid-glass interface both in space and in time as well as the underlying particle motion responsible for its propagation. We perform a detailed statistical analysis of the interface geometry and kinetics over a broad range of temperatures. We show that the dynamic heterogeneity of the bulk liquid is passed on to the front that propagates heterogeneously in space and intermittently in time. This observation allows us to relate the averaged front velocity to the equilibrium diffusion coefficient of the liquid. We suggest that an experimental characterization of the interface geometry during the heterogeneous devitrification of ultrastable glassy films could provide direct experimental access to the long-sought characteristic length scale of dynamic heterogeneity in bulk supercooled liquids.
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Affiliation(s)
- Cecilia Herrero
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France
| | - Mark D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Ludovic Berthier
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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4
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Cheng S, Lee Y, Yu J, Yu L, Ediger MD. Surface Equilibration Mechanism Controls the Stability of a Model Codeposited Glass Mixture of Organic Semiconductors. J Phys Chem Lett 2023; 14:4297-4303. [PMID: 37129465 DOI: 10.1021/acs.jpclett.3c00728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
While previous work has identified the conditions for preparing ultrastable single-component organic glasses by physical vapor deposition (PVD), little is known about the stability of codeposited mixtures. Here, we prepared binary PVD glasses of organic semiconductors, TPD (N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine) and m-MTDATA (4,4',4″-Tris[phenyl(m-tolyl)amino]triphenylamine), with a 50:50 mass concentration over a wide range of substrate temperatures (Tsub). The enthalpy and kinetic stability are evaluated with differential scanning calorimetry and spectroscopic ellipsometry. Binary organic semiconductor glasses with exceptional thermodynamic and kinetic stability comparable to the most stable single-component organic glasses are obtained when deposited at Tsub = 0.78-0.90Tg (where Tg is the conventional glass transition temperature). When deposited at 0.94Tg, the enthalpy of the m-MTDATA/TPD glass equals that expected for the equilibrium liquid at that temperature. Thus, the surface equilibration mechanism previously advanced for single-component PVD glasses is also applicable for these codeposited glasses. These results provide an avenue for designing high-performance organic electronic devices.
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Affiliation(s)
- Shinian Cheng
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Yejung Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Junguang Yu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Lian Yu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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5
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Herrero C, Scalliet C, Ediger MD, Berthier L. Two-step devitrification of ultrastable glasses. Proc Natl Acad Sci U S A 2023; 120:e2220824120. [PMID: 37040403 PMCID: PMC10120036 DOI: 10.1073/pnas.2220824120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/11/2023] [Indexed: 04/12/2023] Open
Abstract
The discovery of ultrastable glasses raises novel challenges about glassy systems. Recent experiments studied the macroscopic devitrification of ultrastable glasses into liquids upon heating but lacked microscopic resolution. We use molecular dynamics simulations to analyze the kinetics of this transformation. In the most stable systems, devitrification occurs after a very large time, but the liquid emerges in two steps. At short times, we observe the rare nucleation and slow growth of isolated droplets containing a liquid maintained under pressure by the rigidity of the surrounding glass. At large times, pressure is released after the droplets coalesce into large domains, which accelerates devitrification. This two-step process produces pronounced deviations from the classical Avrami kinetics and explains the emergence of a giant lengthscale characterizing the devitrification of bulk ultrastable glasses. Our study elucidates the nonequilibrium kinetics of glasses following a large temperature jump, which differs from both equilibrium relaxation and aging dynamics, and will guide future experimental studies.
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Affiliation(s)
- Cecilia Herrero
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier34095, France
| | - Camille Scalliet
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, CambridgeCB3 0WA, United Kingdom
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI53706
| | - Ludovic Berthier
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier34095, France
- Yusuf Hamied Department of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
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6
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Zhang Q, Li W, Qiao K, Han Y. Surface premelting and melting of colloidal glasses. SCIENCE ADVANCES 2023; 9:eadf1101. [PMID: 36930717 PMCID: PMC10022898 DOI: 10.1126/sciadv.adf1101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
The nature of liquid-to-glass transition is a major puzzle in science. A similar challenge exists in glass-to-liquid transition, i.e., glass melting, especially for the poorly investigated surface effects. Here, we assemble colloidal glasses by vapor deposition and melt them by tuning particle attractions. The structural and dynamic parameters saturate at different depths, which define a surface liquid layer and an intermediate glassy layer. The power-law growth of both layers and melting front behaviors at different heating rates are similar to crystal premelting and melting, suggesting that premelting and melting can be generalized to amorphous solids. The measured single-particle kinetics reveal various features and confirm theoretical predictions for glass surface layer.
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Affiliation(s)
- Qi Zhang
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Wei Li
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Kaiyao Qiao
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Yilong Han
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
- Hong Kong University of Science and Technology, Shenzhen Research Institute, Shenzhen 518057, China
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7
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Gasparotto P, Fitzner M, Cox SJ, Sosso GC, Michaelides A. How do interfaces alter the dynamics of supercooled water? NANOSCALE 2022; 14:4254-4262. [PMID: 35244128 DOI: 10.1039/d2nr00387b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The structure of liquid water in the proximity of an interface can deviate significantly from that of bulk water, with surface-induced structural perturbations typically converging to bulk values at about ∼1 nm from the interface. While these structural changes are well established it is, in contrast, less clear how an interface perturbs the dynamics of water molecules within the liquid. Here, through an extensive set of molecular dynamics simulations of supercooled bulk and interfacial water films and nano-droplets, we observe the formation of persistent, spatially extended dynamical domains in which the average mobility varies as a function of the distance from the interface. This is in stark contrast with the dynamical heterogeneity observed in bulk water, where these domains average out spatially over time. We also find that the dynamical response of water to an interface depends critically on the nature of the interface and on the choice of interface definition. Overall these results reveal a richness in the dynamics of interfacial water that opens up the prospect of tuning the dynamical response of water through specific modifications of the interface structure or confining material.
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Affiliation(s)
- Piero Gasparotto
- Scientific Computing Division, Paul Scherrer Institute, Villigen 5232, Switzerland.
| | - Martin Fitzner
- Thomas Young Centre, London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Stephen James Cox
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Gabriele Cesare Sosso
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Angelos Michaelides
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
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8
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Kusters GLA, Tito NB, Storm C, van der Schoot P. Controlling permeation in electrically deforming liquid crystal network films: A dynamical Landau theory. Phys Rev E 2021; 104:054701. [PMID: 34942727 DOI: 10.1103/physreve.104.054701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 11/02/2021] [Indexed: 11/07/2022]
Abstract
Liquid crystal networks exploit the coupling between the responsivity of liquid crystalline mesogens, e.g., to electric fields, and the (visco)elastic properties of a polymer network. Because of this, these materials have been put forward for a wide array of applications, including responsive surfaces such as artificial skins and membranes. For such applications, the desired functional response must generally be realized under strict geometrical constraints, such as provided by supported thin films. To model such settings, we present a dynamical, spatially heterogeneous Landau-type theory for electrically actuated liquid crystal network films. We find that the response of the liquid crystal network permeates the film from top to bottom, and illustrate how this affects the timescale associated with macroscopic deformation. Finally, by linking our model parameters to experimental quantities, we suggest that the permeation rate can be controlled by varying the aspect ratio of the mesogens and their degree of orientational order when crosslinked into the polymer network, for which we predict a single optimum. Our results contribute specifically to the rational design of future applications involving transport or on-demand release of molecular cargo in liquid crystal network films.
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Affiliation(s)
- Guido L A Kusters
- Department of Applied Physics, Eindhoven University of Technology, The Netherlands
| | | | - Cornelis Storm
- Department of Applied Physics, Eindhoven University of Technology, The Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands
| | - Paul van der Schoot
- Department of Applied Physics, Eindhoven University of Technology, The Netherlands
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9
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Whitelam S, Harrowell P. Deposition control of model glasses with surface-mediated orientational order. J Chem Phys 2021; 155:124502. [PMID: 34598548 DOI: 10.1063/5.0061042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We introduce a minimal model of solid-forming anisotropic molecules that displays, in thermal equilibrium, surface orientational order without bulk orientational order. The model reproduces the nonequilibrium behavior of recent experiments in which a bulk nonequilibrium structure grown by deposition contains regions of orientational order characteristic of the surface equilibrium. This order is deposited, in general, in a nonuniform way because of the emergence of a growth-poisoning mechanism that causes equilibrated surfaces to grow slower than non-equilibrated surfaces. We use evolutionary methods to design oscillatory protocols able to grow nonequilibrium structures with uniform order, demonstrating the potential of protocol design for the fabrication of this class of materials.
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Affiliation(s)
- Stephen Whitelam
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Peter Harrowell
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
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10
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Luo P, Zhu F, Lv YM, Lu Z, Shen LQ, Zhao R, Sun YT, Vaughan GBM, di Michiel M, Ruta B, Bai HY, Wang WH. Microscopic Structural Evolution during Ultrastable Metallic Glass Formation. ACS APPLIED MATERIALS & INTERFACES 2021; 13:40098-40105. [PMID: 34375527 DOI: 10.1021/acsami.1c10716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
By decreasing the rate of physical vapor deposition, ZrCuAl metallic glasses with improved stability and mechanical performances can be formed, while the microscopic structural mechanisms remain unclear. Here, with scanning transmission electron microscopy and high-energy synchrotron X-ray diffraction, we found that the metallic glass deposited at a higher rate exhibits a heterogeneous structure with compositional fluctuations at a distance of a few nanometers, which gradually disappear on decreasing the deposition rate; eventually, a homogeneous structure is developed approaching ultrastability. This microscopic structural evolution suggests the existence of the following two dynamical processes during ultrastable metallic glass formation: a faster diffusion process driven by the kinetic energy of the depositing atoms, which results in nanoscale compositional fluctuations, and a slower collective relaxation process that eliminates the compositional and structural heterogeneity, equilibrates the deposited atoms, and strengthens the local atomic connectivity.
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Affiliation(s)
- Peng Luo
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Fan Zhu
- Department of Materials Science, Fudan University, Shanghai 200433, China
| | - Yu-Miao Lv
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhen Lu
- World Premier International Research Centers Initiative (WPI), Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Lai-Quan Shen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Rui Zhao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yi-Tao Sun
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Gavin B M Vaughan
- ESRF-The European Synchrotron, CS 40220, Grenoble 38043 Cedex 9, France
| | - Marco di Michiel
- ESRF-The European Synchrotron, CS 40220, Grenoble 38043 Cedex 9, France
| | - Beatrice Ruta
- ESRF-The European Synchrotron, CS 40220, Grenoble 38043 Cedex 9, France
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Villeurbanne 69622, France
| | - Hai-Yang Bai
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei-Hua Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Riechers B, Guiseppi-Elie A, Ediger MD, Richert R. Dielectric properties of vapor-deposited propylbenzenes. J Chem Phys 2019; 151:174503. [DOI: 10.1063/1.5125138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Birte Riechers
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, USA
| | - A. Guiseppi-Elie
- Department of Biomedical Engineering, The Dwight Look College of Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Ranko Richert
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, USA
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12
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Flenner E, Berthier L, Charbonneau P, Fullerton CJ. Front-Mediated Melting of Isotropic Ultrastable Glasses. PHYSICAL REVIEW LETTERS 2019; 123:175501. [PMID: 31702270 DOI: 10.1103/physrevlett.123.175501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Indexed: 06/10/2023]
Abstract
Ultrastable vapor-deposited glasses display uncommon material properties. Most remarkably, upon heating they are believed to melt via a liquid front that originates at the free surface and propagates over a mesoscopic crossover length, before crossing over to bulk melting. We combine swap Monte Carlo with molecular dynamics simulations to prepare and melt isotropic amorphous films of unprecedendtly high kinetic stability. We are able to directly observe both bulk and front melting, and the crossover between them. We measure the front velocity over a broad range of conditions, and a crossover length scale that grows to nearly 400 particle diameters in the regime accessible to simulations. Our results disentangle the relative roles of kinetic stability and vapor deposition in the physical properties of stable glasses.
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Affiliation(s)
- Elijah Flenner
- Department of Chemistry, Colorado State University, Fort Collins Colorado 80523, USA
| | - Ludovic Berthier
- Laboratoire Charles Coulomb (L2C), University of Montpellier, CNRS, Montpellier, France
| | - Patrick Charbonneau
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - Christopher J Fullerton
- Laboratoire Charles Coulomb (L2C), University of Montpellier, CNRS, Montpellier, France
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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13
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Bolshak G, Chatterjee R, Lieberman R, Shokef Y. Kinetically constrained model for gravity-driven granular flow and clogging. Phys Rev E 2019; 100:032137. [PMID: 31639892 DOI: 10.1103/physreve.100.032137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Indexed: 11/07/2022]
Abstract
We add extreme driving to the Kob-Andersen kinetically constrained lattice-gas model in order to mimic the effect of gravity on dense granular systems. For low particle densities, the current that develops in the system agrees at arbitrary field intensity with a mean-field theory. At intermediate densities, spatial correlations give rise to nonmonotonic dependence of the current on field intensity. At higher densities, the current ultimately vanishes at a finite, field-dependent density. We supplement the study of this bulk behavior with an investigation of the current through a narrow hole. There, lateral flow decreases the local density in front of the hole. Remarkably, the current through the hole quantitatively agrees with a theoretical prediction based on the bulk current at the measured local density.
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Affiliation(s)
- Gregory Bolshak
- School of Mechanical Engineering and Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - Rakesh Chatterjee
- School of Mechanical Engineering and Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | | | - Yair Shokef
- School of Mechanical Engineering and Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
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14
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Orientationally ordered glasses via controlled deposition. Proc Natl Acad Sci U S A 2019; 116:21341-21342. [PMID: 31578254 DOI: 10.1073/pnas.1915691116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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15
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Zheng Q, Zhang Y, Montazerian M, Gulbiten O, Mauro JC, Zanotto ED, Yue Y. Understanding Glass through Differential Scanning Calorimetry. Chem Rev 2019; 119:7848-7939. [DOI: 10.1021/acs.chemrev.8b00510] [Citation(s) in RCA: 154] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qiuju Zheng
- School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
| | - Yanfei Zhang
- School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
| | - Maziar Montazerian
- Vitreous Materials Laboratory (LaMaV), Department of Materials Engineering (DEMa), Federal University of São Carlos (UFSCar), 13.565-905 São Carlos, SP, Brazil
| | - Ozgur Gulbiten
- Science and Technology Division, Corning Incorporated, Corning, New York 14831, United States
| | - John C. Mauro
- School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Edgar D. Zanotto
- Vitreous Materials Laboratory (LaMaV), Department of Materials Engineering (DEMa), Federal University of São Carlos (UFSCar), 13.565-905 São Carlos, SP, Brazil
| | - Yuanzheng Yue
- School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
- Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg, Denmark
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16
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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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17
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Douglass I, Harrowell P. Formation of Ultrastable Glasses via Precipitation: A Modeling Study. PHYSICAL REVIEW LETTERS 2019; 122:088003. [PMID: 30932562 DOI: 10.1103/physrevlett.122.088003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 11/09/2018] [Indexed: 06/09/2023]
Abstract
The precipitation of a glass forming solute from solution is modeled using a lattice model previously introduced to study dissolution kinetics of amorphous materials. The model includes the enhancement of kinetics at the surface of a glass in contact with a plasticizing solvent. We demonstrate that precipitation can produce a glass substantially more stable than that produced by very long time annealing of the bulk glass former. The energy of these ultrastable amorphous precipitates is found to be dominated by residual solvent rather than high energy glass configurations.
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Affiliation(s)
- Ian Douglass
- School of Chemistry, University of Sydney, Sydney 2006 New South Wales, Australia
| | - Peter Harrowell
- School of Chemistry, University of Sydney, Sydney 2006 New South Wales, Australia
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18
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Ràfols-Ribé J, Vila-Costa A, Rodríguez-Tinoco C, Lopeandía AF, Rodríguez-Viejo J, Gonzalez-Silveira M. Kinetic arrest of front transformation to gain access to the bulk glass transition in ultrathin films of vapour-deposited glasses. Phys Chem Chem Phys 2018; 20:29989-29995. [PMID: 30480265 DOI: 10.1039/c8cp06264a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Physical vapour deposition has emerged as the technique to obtain glasses of unbeatable stability. However, vapour deposited glasses exhibit a different transformation mechanism to ordinary glasses produced from liquid. Vapour deposited glasses of different thermodynamic stability, from ultrastable to those similar to ordinary glasses, transform into the liquid state via front propagation starting at the most mobile surfaces/interfaces, at least for the first stages of the transformation, eventually dynamiting the high thermal stability achieved for some of these glasses. A previous study showed that it was possible to avoid this transformation front by capping the films with a higher Tg material. We show here fast calorimetry measurements on TPD and IMC vapour deposited glasses capped respectively with TCTA and TPD. This capped configuration is very effective in suppressing the heterogeneous transformation of the stable glasses into the supercooled liquid and shifts the devitrification temperature to much higher values, where the bulk homogeneous mechanism becomes active. This approach may be useful to further study the bulk glass transition in thin films.
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Affiliation(s)
- Joan Ràfols-Ribé
- Group of Nanomaterials and Microsystems, Physics Department, Universitat Autònoma de Barcelona, Barcelona, 08193 - Bellaterra, Spain.
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19
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Chen Z, Qi W, Bowles RK. Glass forming phase diagram and local structure of Kob-Andersen binary Lennard-Jones nanoparticles. J Chem Phys 2018; 149:094502. [PMID: 30195318 DOI: 10.1063/1.5047465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Molecular dynamics simulation is used to study glass formation in Kob-Andersen binary Lennard-Jones nanoparticles and determine the glass forming phase diagram for the system as a function of composition. The radial distribution function, a Steinhardt bond-orientational order parameter, and favored local structure analysis are used to distinguish between glassy and ordered systems. We find that surface enrichment of the large atoms alters the nanoparticle core composition, leading to an overall shift of the glass forming region to lower small atom mole fractions, relative to the bulk system. At small atom mole fraction, xB = 0.1, the nanoparticles form a solid with an amorphous core, enriched with the small atoms, surrounded by a partially ordered surface region, enriched with the large atom component. The most disordered glass nanoparticles occur at xB ≈ 0.3, but the surface-core enrichment leads to the crystallization of the nanoparticle to the CsCl crystal above xB ≈ 0.35, which is lower than observed in the bulk. The glass transition temperatures of the nanoparticles are also significantly reduced. This allows the liquid to remain dynamic to low temperatures and sample the low energy inherent structure minima on the potential energy surface containing a high abundance of favoured local structures.
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Affiliation(s)
- Zhongquan Chen
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Weikai Qi
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Richard K Bowles
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
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20
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Kearns KL, Krzyskowski P, Devereaux Z. Using deposition rate to increase the thermal and kinetic stability of vapor-deposited hole transport layer glasses via a simple sublimation apparatus. J Chem Phys 2018; 146:203328. [PMID: 28571345 DOI: 10.1063/1.4979814] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Deposition rate is known to affect the relative stability of vapor-deposited glasses; slower rates give more stable materials due to enhanced mobility at the free surface of the film. Here we show that the deposition rate can affect both the thermodynamic and kinetic stabilities of N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD) and N,N'-di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl)-4,4'-diamine (NPD) glasses used as hole transport layers for organic light emitting diodes (OLEDs). A simple, low-vacuum glass sublimation apparatus and a high vacuum deposition chamber were used to deposit the glass. 50 μm thick films were deposited in the sublimation apparatus and characterized by differential scanning calorimetry while 75 nm thick films were prepared in the high vacuum chamber and studied by hot-stage spectroscopic ellipsometry (SE). The thermodynamic stability from both preparation chambers was consistent and showed that the fictive temperature (Tfictive) was more than 30 K lower than the conventional glass transition temperature (Tg) at the slowest deposition rates. The kinetic stability, measured as the onset temperature (Tonset) where the glass begins to transform into the supercooled liquid, was 16-17 K greater than Tg at the slowest rates. Tonset was systematically lower for the thin films characterized by SE and was attributed to the thickness dependent transformation of the glass into the supercooled liquid. These results show the first calorimetric characterization of the stability of glasses for OLED applications made by vapor deposition and the first direct comparison of deposition apparatuses as a function of the deposition rate. The ease of fabrication will create an opportunity for others to study the effect of deposition conditions on glass stability.
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Affiliation(s)
- Kenneth L Kearns
- Department of Chemistry, Saginaw Valley State University, University Center, Michigan 48710, USA
| | - Paige Krzyskowski
- Department of Chemistry, Saginaw Valley State University, University Center, Michigan 48710, USA
| | - Zachary Devereaux
- Department of Chemistry, Saginaw Valley State University, University Center, Michigan 48710, USA
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21
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Abstract
The kinetics of dissolution of an amorphous solid is studied using a simple model of a glass that captures with reasonable accuracy the dynamic heterogeneities associated with the relaxation of an amorphous material at low temperatures. The intrinsic dissolution rate is shown to be proportional to the concentration of surface particles kinetically able to exchange with the solvent, independent of temperature or the thermal history of the glass. The morphology of the dissolving surface is described, and the possibility of using surface etching to image dynamic heterogeneities is explored.
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Affiliation(s)
- Ian Douglass
- School of Chemistry, University of Sydney , Sydney, NSW 2006, Australia
| | - Peter Harrowell
- School of Chemistry, University of Sydney , Sydney, NSW 2006, Australia
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22
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Affiliation(s)
- Ian Douglass
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Peter Harrowell
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
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23
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Sun G, Saw S, Douglass I, Harrowell P. Structural Origin of Enhanced Dynamics at the Surface of a Glassy Alloy. PHYSICAL REVIEW LETTERS 2017; 119:245501. [PMID: 29286748 DOI: 10.1103/physrevlett.119.245501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Indexed: 06/07/2023]
Abstract
The enhancement of mobility at the surface of an amorphous alloy is studied using a combination of molecular dynamic simulations and normal mode analysis of the nonuniform distribution of Debye-Waller factors. The increased mobility at the surface is found to be associated with the appearance of Arrhenius temperature dependence. We show that the transverse Debye-Waller factor exhibits a peak at the surface. Over the accessible temperature range, we find that the bulk and surface diffusion coefficients obey the same empirical relationship with the respective Debye-Waller factors. Extrapolating this relationship to lower T, we argue that the observed decrease in the constraint at the surface is sufficient to account for the experimentally observed surface enhancement of mobility.
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Affiliation(s)
- Gang Sun
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Shibu Saw
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Ian Douglass
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Peter Harrowell
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
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24
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Affiliation(s)
- M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison,
1101 University Avenue, Madison, Wisconsin 53706, USA
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25
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Sussman DM, Schoenholz SS, Cubuk ED, Liu AJ. Disconnecting structure and dynamics in glassy thin films. Proc Natl Acad Sci U S A 2017; 114:10601-10605. [PMID: 28928147 PMCID: PMC5635874 DOI: 10.1073/pnas.1703927114] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nanometrically thin glassy films depart strikingly from the behavior of their bulk counterparts. We investigate whether the dynamical differences between a bulk and thin film polymeric glass former can be understood by differences in local microscopic structure. Machine learning methods have shown that local structure can serve as the foundation for successful, predictive models of particle rearrangement dynamics in bulk systems. By contrast, in thin glassy films, we find that particles at the center of the film and those near the surface are structurally indistinguishable despite exhibiting very different dynamics. Next, we show that structure-independent processes, already present in bulk systems and demonstrably different from simple facilitated dynamics, are crucial for understanding glassy dynamics in thin films. Our analysis suggests a picture of glassy dynamics in which two dynamical processes coexist, with relative strengths that depend on the distance from an interface. One of these processes depends on local structure and is unchanged throughout most of the film, while the other is purely Arrhenius, does not depend on local structure, and is strongly enhanced near the free surface of a film.
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Affiliation(s)
| | | | - Ekin D Cubuk
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94304
| | - Andrea J Liu
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
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26
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Zhang W, Douglas JF, Starr FW. Dynamical heterogeneity in a vapor-deposited polymer glass. J Chem Phys 2017; 146:203310. [DOI: 10.1063/1.4976542] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Wengang Zhang
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Francis W. Starr
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, USA
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27
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Mirigian S, Schweizer KS. Influence of chemistry, interfacial width, and non-isothermal conditions on spatially heterogeneous activated relaxation and elasticity in glass-forming free standing films. J Chem Phys 2017; 146:203301. [PMID: 28571330 DOI: 10.1063/1.4974766] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Stephen Mirigian
- Departments of Materials Science and Chemistry, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801, USA
| | - Kenneth S. Schweizer
- Departments of Materials Science and Chemistry, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801, USA
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28
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Napolitano S, Glynos E, Tito NB. Glass transition of polymers in bulk, confined geometries, and near interfaces. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:036602. [PMID: 28134134 DOI: 10.1088/1361-6633/aa5284] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
When cooled or pressurized, polymer melts exhibit a tremendous reduction in molecular mobility. If the process is performed at a constant rate, the structural relaxation time of the liquid eventually exceeds the time allowed for equilibration. This brings the system out of equilibrium, and the liquid is operationally defined as a glass-a solid lacking long-range order. Despite almost 100 years of research on the (liquid/)glass transition, it is not yet clear which molecular mechanisms are responsible for the unique slow-down in molecular dynamics. In this review, we first introduce the reader to experimental methodologies, theories, and simulations of glassy polymer dynamics and vitrification. We then analyse the impact of connectivity, structure, and chain environment on molecular motion at the length scale of a few monomers, as well as how macromolecular architecture affects the glass transition of non-linear polymers. We then discuss a revised picture of nanoconfinement, going beyond a simple picture based on interfacial interactions and surface/volume ratio. Analysis of a large body of experimental evidence, results from molecular simulations, and predictions from theory supports, instead, a more complex framework where other parameters are relevant. We focus discussion specifically on local order, free volume, irreversible chain adsorption, the Debye-Waller factor of confined and confining media, chain rigidity, and the absolute value of the vitrification temperature. We end by highlighting the molecular origin of distributions in relaxation times and glass transition temperatures which exceed, by far, the size of a chain. Fast relaxation modes, almost universally present at the free surface between polymer and air, are also remarked upon. These modes relax at rates far larger than those characteristic of glassy dynamics in bulk. We speculate on how these may be a signature of unique relaxation processes occurring in confined or heterogeneous polymeric systems.
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Affiliation(s)
- Simone Napolitano
- Laboratory of Polymer and Soft Matter Dynamics, Faculté des Sciences, Université Libre de Bruxelles (ULB), Boulevard du Triomphe, 1050 Brussels, Belgium
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29
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Gómez J, Gujral A, Huang C, Bishop C, Yu L, Ediger MD. Nematic-like stable glasses without equilibrium liquid crystal phases. J Chem Phys 2017; 146:054503. [DOI: 10.1063/1.4974829] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Jaritza Gómez
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Ankit Gujral
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Chengbin Huang
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, USA
| | - Camille Bishop
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Lian Yu
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, USA
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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30
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Teomy E, Shokef Y. Hydrodynamics in kinetically constrained lattice-gas models. Phys Rev E 2017; 95:022124. [PMID: 28297932 DOI: 10.1103/physreve.95.022124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 06/06/2023]
Abstract
Kinetically constrained models are lattice-gas models that are used for describing glassy systems. By construction, their equilibrium state is trivial and there are no equal-time correlations between the occupancy of different sites. We drive such models out of equilibrium by connecting them to two reservoirs of different densities, and we measure the response of the system to this perturbation. We find that under the proper coarse-graining, the behavior of these models may be expressed by a nonlinear diffusion equation, with a model- and density-dependent diffusion coefficient. We find a simple approximation for the diffusion coefficient, and we show that the relatively mild discrepancy between the approximation and our numerical results arises due to non-negligible correlations that appear as the system is driven out of equilibrium, even when the density gradient is infinitesimally small. Similar correlations appear when such kinetically constrained models are driven out of equilibrium by applying a uniform external force. We suggest that these correlations are the reason for the same discrepancy between the approximate diffusion coefficient and the numerical results for a broader group of models-nongradient lattice-gas models-for which kinetically constrained models are arguably the simplest example thereof.
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Affiliation(s)
- Eial Teomy
- School of Mechanical Engineering and Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
- Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel
| | - Yair Shokef
- School of Mechanical Engineering and Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
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31
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Ràfols-Ribé J, Gonzalez-Silveira M, Rodríguez-Tinoco C, Rodríguez-Viejo J. The role of thermodynamic stability in the characteristics of the devitrification front of vapour-deposited glasses of toluene. Phys Chem Chem Phys 2017; 19:11089-11097. [DOI: 10.1039/c7cp00741h] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Glass stability and molecular shape affect the transformation mechanism of vapour deposited glasses.
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Affiliation(s)
- Joan Ràfols-Ribé
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universtitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
| | - Marta Gonzalez-Silveira
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universtitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
| | - Cristian Rodríguez-Tinoco
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universtitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
| | - Javier Rodríguez-Viejo
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universtitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
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32
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Staley H, Flenner E, Szamel G. Kinetic stability and energetics of simulated glasses createdby constant pressure cooling. J Chem Phys 2016; 145:184505. [PMID: 27846707 DOI: 10.1063/1.4967337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We use computer simulations to study the cooling rate dependence of the stability and energetics of model glasses created at constant pressure conditions and compare the results with glasses formed at constant volume conditions. To examine the stability, we determine the time it takes for a glass cooled and reheated at constant pressure to transform back into a liquid, ttrans, and calculate the stability ratio S=ttrans/τα, where τα is the equilibrium relaxation time of the liquid. We find that, for slow enough cooling rates, cooling and reheating at constant pressure results in a larger stability ratio S than for cooling and reheating at constant volume. We also compare the energetics of glasses obtained by cooling while maintaining constant pressure with those of glasses created by cooling from the same state point while maintaining constant volume. We find that cooling at constant pressure results in glasses with lower average potential energy and average inherent structure energy. We note that in model simulations of the vapor deposition process, glasses are created under constant pressure conditions, and thus they should be compared to glasses obtained by constant pressure cooling.
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Affiliation(s)
- Hannah Staley
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Elijah Flenner
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Grzegorz Szamel
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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33
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Tylinski M, Chua YZ, Beasley MS, Schick C, Ediger MD. Vapor-deposited alcohol glasses reveal a wide range of kinetic stability. J Chem Phys 2016; 145:174506. [DOI: 10.1063/1.4966582] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- M. Tylinski
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
| | - Y. Z. Chua
- Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18051 Rostock, Germany and Competence Centre CALOR, Faculty of Interdisciplinary Research, University of Rostock, Albert-Einstein-Str. 25, 18051 Rostock, Germany
| | - M. S. Beasley
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
| | - C. Schick
- Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18051 Rostock, Germany and Competence Centre CALOR, Faculty of Interdisciplinary Research, University of Rostock, Albert-Einstein-Str. 25, 18051 Rostock, Germany
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
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34
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Chua YZ, Tylinski M, Tatsumi S, Ediger MD, Schick C. Glass transition and stable glass formation of tetrachloromethane. J Chem Phys 2016; 144:244503. [PMID: 27369523 DOI: 10.1063/1.4954665] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Physical vapor deposition (PVD) has been used to prepare organic glasses with very high kinetic stability and it has been suggested that molecular anisotropy is a prerequisite for stable glass formation. Here we use PVD to prepare glasses of tetrachloromethane, a simple organic molecule with a nearly isotropic molecular structure. In situ AC nanocalorimetry was used to characterize the vapor-deposited glasses. Glasses of high kinetic stability were produced by deposition near 0.8 Tg. The isothermal transformation of the vapor-deposited glasses into the supercooled liquid state gave further evidence that tetrachloromethane forms glasses with high kinetic stability, with the transformation time exceeding the structural relaxation time of the supercooled liquid by a factor of 10(3). The glass transition temperature of liquid-cooled tetrachloromethane is determined as Tg ≈ 78 K, which is different from previously reported values. The frequency dependence of the glass transition was also determined and the fragility was estimated as m ≈ 118. The successful formation of PVD glasses of tetrachloromethane which have high kinetic stability argues that molecular asymmetry is not a prerequisite for stable glass formation.
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Affiliation(s)
- Y Z Chua
- Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18059 Rostock, Germany
| | - M Tylinski
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S Tatsumi
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - C Schick
- Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18059 Rostock, Germany
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35
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Jack RL, Berthier L. The melting of stable glasses is governed by nucleation-and-growth dynamics. J Chem Phys 2016; 144:244506. [PMID: 27369526 DOI: 10.1063/1.4954327] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We discuss the microscopic mechanisms by which low-temperature amorphous states, such as ultrastable glasses, transform into equilibrium fluids, after a sudden temperature increase. Experiments suggest that this process is similar to the melting of crystals, thus differing from the behaviour found in ordinary glasses. We rationalize these observations using the physical idea that the transformation process takes place close to a "hidden" equilibrium first-order phase transition, which is observed in systems of coupled replicas. We illustrate our views using simulation results for a simple two-dimensional plaquette spin model, which is known to exhibit a range of glassy behaviour. Our results suggest that nucleation-and-growth dynamics, as found near ordinary first-order transitions, is also the correct theoretical framework to analyse the melting of ultrastable glasses. Our approach provides a unified understanding of multiple experimental observations, such as propagating melting fronts, large kinetic stability ratios, and "giant" dynamic length scales. We also provide a comprehensive discussion of available theoretical pictures proposed in the context of ultrastable glass melting.
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Affiliation(s)
- Robert L Jack
- Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Ludovic Berthier
- Laboratoire Charles Coulomb, UMR 5221 CNRS-Université de Montpellier, 34095 Montpellier, France
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36
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Tylinski M, Sepúlveda A, Walters DM, Chua YZ, Schick C, Ediger MD. Vapor-deposited glasses of methyl-m-toluate: How uniform is stable glass transformation? J Chem Phys 2015; 143:244509. [PMID: 26723694 DOI: 10.1063/1.4938420] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
AC chip nanocalorimetry is used to characterize vapor-deposited glasses of methyl-m-toluate (MMT). Physical vapor deposition can prepare MMT glasses that have lower heat capacity and significantly higher kinetic stability compared to liquid-cooled glasses. When heated, highly stable MMT glasses transform into the supercooled liquid via propagating fronts. We present the first quantitative analysis of the temporal and spatial uniformities of these transformation fronts. The front velocity varies by less than 4% over the duration of the transformation. For films 280 nm thick, the transformation rates at different spatial positions in the film differ by about 25%; this quantity may be related to spatially heterogeneous dynamics in the stable glass. Our characterization of the kinetic stability of MMT stable glasses extends previous dielectric experiments and is in excellent agreement with these results.
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Affiliation(s)
- M Tylinski
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Sepúlveda
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Diane M Walters
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Y Z Chua
- Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18051 Rostock, Germany
| | - C Schick
- Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18051 Rostock, Germany
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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37
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Lyubimov I, Antony L, Walters DM, Rodney D, Ediger MD, de Pablo JJ. Orientational anisotropy in simulated vapor-deposited molecular glasses. J Chem Phys 2015; 143:094502. [PMID: 26342372 DOI: 10.1063/1.4928523] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Enhanced kinetic stability of vapor-deposited glasses has been established for a variety of glass organic formers. Several recent reports indicate that vapor-deposited glasses can be orientationally anisotropic. In this work, we present results of extensive molecular simulations that mimic a number of features of the experimental vapor deposition process. The simulations are performed on a generic coarse-grained model and an all-atom representation of N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD), a small organic molecule whose vapor-deposited glasses exhibit considerable orientational anisotropy. The coarse-grained model adopted here is found to reproduce several key aspects reported in experiments. In particular, the molecular orientation of vapor-deposited glasses is observed to depend on substrate temperature during deposition. For a fixed deposition rate, the molecular orientation in the glasses changes from isotropic, at the glass transition temperature, Tg, to slightly normal to the substrate at temperatures just below Tg. Well below Tg, molecular orientation becomes predominantly parallel to the substrate. The all-atom model is used to confirm some of the equilibrium structural features of TPD interfaces that arise above the glass transition temperature. We discuss a mechanism based on distinct orientations observed at equilibrium near the surface of the film, which get trapped within the film during the non-equilibrium process of vapor deposition.
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Affiliation(s)
- Ivan Lyubimov
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Lucas Antony
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Diane M Walters
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - David Rodney
- Science et Ingénierie des Matériaux et Procédés, Grenoble INP, CNRS/UJF, 38402 Saint Martin d'Hères, France
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Juan J de Pablo
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
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38
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Tito NB, Milner ST, Lipson JEG. Enhanced diffusion and mobile fronts in a simple lattice model of glass-forming liquids. SOFT MATTER 2015; 11:7792-7801. [PMID: 26313541 DOI: 10.1039/c5sm01701g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The diffusion of mobility in bulk and thin film fluids near their glass transition is examined with a kinetic lattice model, and compared to recent experiments on bulk liquids and vapor-deposited thin film glasses. The "limited mobility" (LM) lattice model exhibits dynamic heterogeneity of mobility when the fluid is near its kinetic arrest transition; a finite-parameter second-order critical point in the LM model bearing strong resemblance to the glass transition in real fluids. The spatial heterogeneity of mobility near kinetic arrest leads to dynamics that violate the Stokes-Einstein relation. To make connections with experiment, LM model simulations of self-diffusion constants in fluids near kinetic arrest are compared to those in two organic glass-formers. In addition, simulations of mobility in films that have been temperature-jumped above kinetic arrest (starting from an arrested state) are carried out. The films develop a "front" of mobility at their free surface that progresses into the film interior at a constant rate, thereby mobilising the entire film to fluidity. The velocity of the front scales with the self-diffusion constant for analogous bulk systems-an observation consistent with experiments on vapor-deposited molecular thin films.
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Affiliation(s)
- Nicholas B Tito
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
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Torres JM, Bakken N, Li J, Vogt BD. Substrate Temperature to Control Moduli and Water Uptake in Thin Films of Vapor Deposited N,N'-Di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPD). J Phys Chem B 2015; 119:11928-34. [PMID: 26230183 DOI: 10.1021/acs.jpcb.5b05814] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ultrastable glasses are generated by vapor deposition on substrates heated near the glass transition temperature (Tg), but it is unclear if the remarkable properties of such glasses are present in ultrathin (<100 nm) films. Here, we demonstrate that the moduli of 50 nm thick N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPD) film can be increased from 1.5 to 2.5 GPa by simply increasing the temperature of the substrate during deposition with a maximum in modulus found at T/Tg = 0.94. This maximum in modulus is the same modulus obtained for very thin (<15 nm) NPD films deposited at 295 K (T/Tg = 0.80). However, the modulus of films deposited at this lower temperature abruptly decreases to approximately 1.5 GPa for thicker films; the modulus from deposition at T/Tg = 0.94 is thickness independent. In addition to the thin film modulus, the substrate temperature significantly impacts the water uptake in NPD films. From QCM, the volume fraction of water at equilibrium with nearly saturated water vapor decreases from nearly 4% to less than 1% as the substrate temperature increases from T/Tg = 0.82 to T/Tg = 0.93. The substrate temperature provides a simple route to control mechanical properties and water uptake into vapor-deposited NPD, and these concepts are likely extendable to other organic electronic materials; the increased moduli and decreased water uptake could enable improved performance and lifetime of small molecule glasses for a variety of organic electronic applications.
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Affiliation(s)
- Jessica M Torres
- School for Engineering of Matter, Transport and Energy, Arizona State University , Temple, Arizona 85284, United States
| | - Nathan Bakken
- School for Engineering of Matter, Transport and Energy, Arizona State University , Temple, Arizona 85284, United States
| | - Jian Li
- School for Engineering of Matter, Transport and Energy, Arizona State University , Temple, Arizona 85284, United States
| | - Bryan D Vogt
- Department of Polymer Engineering, University of Akron , Akron, Ohio 44325, United States
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40
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Chua YZ, Ahrenberg M, Tylinski M, Ediger MD, Schick C. How much time is needed to form a kinetically stable glass? AC calorimetric study of vapor-deposited glasses of ethylcyclohexane. J Chem Phys 2015; 142:054506. [PMID: 25662653 DOI: 10.1063/1.4906806] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Glasses of ethylcyclohexane produced by physical vapor deposition have been characterized by in situ alternating current chip nanocalorimetry. Consistent with previous work on other organic molecules, we observe that glasses of high kinetic stability are formed at substrate temperatures around 0.85 Tg, where Tg is the conventional glass transition temperature. Ethylcyclohexane is the least fragile organic glass-former for which stable glass formation has been established. The isothermal transformation of the vapor-deposited glasses into the supercooled liquid state was also measured. At seven substrate temperatures, the transformation time was measured for glasses prepared with deposition rates across a range of four orders of magnitude. At low substrate temperatures, the transformation time is strongly dependent upon deposition rate, while the dependence weakens as Tg is approached from below. These data provide an estimate for the surface equilibration time required to maximize kinetic stability at each substrate temperature. This surface equilibration time is much smaller than the bulk α-relaxation time and within two orders of magnitude of the β-relaxation time of the ordinary glass. Kinetically stable glasses are formed even for substrate temperatures below the Vogel and the Kauzmann temperatures. Surprisingly, glasses formed in the limit of slow deposition at the lowest substrate temperatures are not as kinetically stable as those formed near 0.85 Tg.
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Affiliation(s)
- Y Z Chua
- Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18051 Rostock, Germany
| | - M Ahrenberg
- Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18051 Rostock, Germany
| | - M Tylinski
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - C Schick
- Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18051 Rostock, Germany
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41
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Staley H, Flenner E, Szamel G. Cooling-rate dependence of kinetic and mechanical stabilities of simulated glasses. J Chem Phys 2015; 142:244508. [PMID: 26133442 DOI: 10.1063/1.4922937] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Glasses created through vapor deposition on a substrate maintained at a proper temperature possess higher kinetic and mechanical stabilities than glasses created by cooling at a constant rate. Molecular dynamics simulations are being increasingly used to understand why vapor deposition improves glasses' stability. There are, however, few detailed molecular dynamics studies of the dependence of the properties of glasses cooled at a constant rate on the rate of cooling. Thus, there is no clear benchmark for comparing ultrastable simulated glasses to simulated glasses prepared through cooling at a constant rate. Here, we examine the dependence of the properties of simulated glasses on the cooling rate used in their preparation. We examine the kinetic stability by measuring the time it takes for a glass to transform back to a liquid upon heating and heterogeneous dynamics during heating. We also examine properties of the energy landscape, and we evaluate mechanical stability by calculating the shear modulus of the glass. The methods outlined here can be used to assess kinetic and mechanical stabilities of simulated glasses generated using specialized algorithms and provide a benchmark for those algorithms.
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Affiliation(s)
- Hannah Staley
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Elijah Flenner
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Grzegorz Szamel
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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42
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Walters DM, Richert R, Ediger MD. Thermal stability of vapor-deposited stable glasses of an organic semiconductor. J Chem Phys 2015; 142:134504. [PMID: 25854250 DOI: 10.1063/1.4916649] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Vapor-deposited organic glasses can show enhanced kinetic stability relative to liquid-cooled glasses. When such stable glasses of model glassformers are annealed above the glass transition temperature Tg, they lose their thermal stability and transform into the supercooled liquid via constant velocity propagating fronts. In this work, we show that vapor-deposited glasses of an organic semiconductor, N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD), also transform via propagating fronts. Using spectroscopic ellipsometry and a new high-throughput annealing protocol, we measure transformation front velocities for TPD glasses prepared with substrate temperatures (TSubstrate) from 0.63 to 0.96 Tg, at many different annealing temperatures. We observe that the front velocity varies by over an order of magnitude with TSubstrate, while the activation energy remains constant. Using dielectric spectroscopy, we measure the structural relaxation time of supercooled TPD. We find that the mobility of the liquid and the structure of the glass are independent factors in controlling the thermal stability of TPD films. In comparison to model glassformers, the transformation fronts of TPD have similar velocities and a similar dependence on TSubstrate, suggesting universal behavior. These results may aid in designing active layers in organic electronic devices with improved thermal stability.
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Affiliation(s)
- Diane M Walters
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Ranko Richert
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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43
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Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors. Proc Natl Acad Sci U S A 2015; 112:4227-32. [PMID: 25831545 DOI: 10.1073/pnas.1421042112] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Physical vapor deposition is commonly used to prepare organic glasses that serve as the active layers in light-emitting diodes, photovoltaics, and other devices. Recent work has shown that orienting the molecules in such organic semiconductors can significantly enhance device performance. We apply a high-throughput characterization scheme to investigate the effect of the substrate temperature (Tsubstrate) on glasses of three organic molecules used as semiconductors. The optical and material properties are evaluated with spectroscopic ellipsometry. We find that molecular orientation in these glasses is continuously tunable and controlled by Tsubstrate/Tg, where Tg is the glass transition temperature. All three molecules can produce highly anisotropic glasses; the dependence of molecular orientation upon substrate temperature is remarkably similar and nearly independent of molecular length. All three compounds form "stable glasses" with high density and thermal stability, and have properties similar to stable glasses prepared from model glass formers. Simulations reproduce the experimental trends and explain molecular orientation in the deposited glasses in terms of the surface properties of the equilibrium liquid. By showing that organic semiconductors form stable glasses, these results provide an avenue for systematic performance optimization of active layers in organic electronics.
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44
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Dalal SS, Ediger MD. Influence of Substrate Temperature on the Transformation Front Velocities That Determine Thermal Stability of Vapor-Deposited Glasses. J Phys Chem B 2015; 119:3875-82. [DOI: 10.1021/jp512905a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Shakeel S. Dalal
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - M. D. Ediger
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
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45
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Rodríguez-Tinoco C, Gonzalez-Silveira M, Ràfols-Ribé J, Lopeandía AF, Rodríguez-Viejo J. Transformation kinetics of vapor-deposited thin film organic glasses: the role of stability and molecular packing anisotropy. Phys Chem Chem Phys 2015; 17:31195-201. [DOI: 10.1039/c5cp04692k] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The growth front velocity of indomethacin glasses depends on deposition conditions but is not unambigously determined by its thermodynamic stability when the structure is not completely isotropic.
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Affiliation(s)
- Cristian Rodríguez-Tinoco
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
| | - Marta Gonzalez-Silveira
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
| | - Joan Ràfols-Ribé
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
| | - Aitor F. Lopeandía
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
| | - Javier Rodríguez-Viejo
- Grup de Nanomaterials i Microsistemes
- Physics Department
- Universitat Autònoma de Barcelona
- 08193 Bellaterra
- Spain
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46
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Hocky GM, Berthier L, Reichman DR. Equilibrium ultrastable glasses produced by random pinning. J Chem Phys 2014; 141:224503. [DOI: 10.1063/1.4903200] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Glen M. Hocky
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - Ludovic Berthier
- Laboratoire Charles Coulomb, UMR 5221, CNRS and Université Montpellier 2, Montpellier, France
| | - David R. Reichman
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
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47
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Rodríguez-Tinoco C, Gonzalez-Silveira M, Ràfols-Ribé J, Lopeandía AF, Clavaguera-Mora MT, Rodríguez-Viejo J. Evaluation of Growth Front Velocity in Ultrastable Glasses of Indomethacin over a Wide Temperature Interval. J Phys Chem B 2014; 118:10795-801. [DOI: 10.1021/jp506782d] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Cristian Rodríguez-Tinoco
- Grup
de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Marta Gonzalez-Silveira
- Grup
de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Joan Ràfols-Ribé
- Grup
de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Aitor F. Lopeandía
- Grup
de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Maria Teresa Clavaguera-Mora
- Grup
de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Javier Rodríguez-Viejo
- Grup
de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- MATGAS Research Centre, Campus
UAB, 08193 Bellaterra, Spain
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48
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Sepúlveda A, Tylinski M, Guiseppi-Elie A, Richert R, Ediger MD. Role of fragility in the formation of highly stable organic glasses. PHYSICAL REVIEW LETTERS 2014; 113:045901. [PMID: 25105633 DOI: 10.1103/physrevlett.113.045901] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Indexed: 06/03/2023]
Abstract
In situ dielectric spectroscopy has been used to characterize vapor-deposited glasses of methyl-m-toluate (MMT), an organic glass former with low fragility (m = 60). Deposition near 0.84T(g) produces glasses of very high kinetic stability; these materials are comparable in stability to the most stable glasses produced from more fragile glass formers. Highly stable glasses of MMT, when annealed above T(g), transform into the supercooled liquid by a heterogeneous mechanism. A constant velocity propagating front is initiated at the free surface and controls the transformation of thin films. The transition to a bulk-dominated transformation process occurs at 5 μm, the largest length scale reported for any glass. Contrary to recent conclusions, we find that physical vapor deposition can form highly stable organic glasses across the entire range of liquid fragilities.
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Affiliation(s)
- A Sepúlveda
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M Tylinski
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Guiseppi-Elie
- Department of Bioengineering, Clemson University, Clemson, South Carolina 29634, USA
| | - R Richert
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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49
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Lin PH, Lyubimov I, Yu L, Ediger MD, de Pablo JJ. Molecular modeling of vapor-deposited polymer glasses. J Chem Phys 2014; 140:204504. [DOI: 10.1063/1.4876078] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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50
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Ishii K, Nakayama H. Structural relaxation of vapor-deposited molecular glasses and supercooled liquids. Phys Chem Chem Phys 2014; 16:12073-92. [DOI: 10.1039/c4cp00458b] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The properties of vapor-deposited molecular glasses largely depend on deposition conditions, and stable and/or dense glasses are formed with several compounds.
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Affiliation(s)
- Kikujiro Ishii
- Department of Chemistry
- Gakushuin University
- Tokyo 171-8588, Japan
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