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Zografi G, Newman A, Shalaev E. Structural Features of the Glassy State and Their Impact on the Solid-State Properties of Organic Molecules in Pharmaceutical Systems. J Pharm Sci 2024:S0022-3549(24)00186-2. [PMID: 38768756 DOI: 10.1016/j.xphs.2024.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/22/2024]
Abstract
This paper reviews the structure and properties of amorphous active pharmaceutical ingredients (APIs), including small molecules and proteins, in the glassy state (below the glass transition temperature, Tg). Amorphous materials in the neat state and formulated with excipients as miscible amorphous mixtures are included, and the role of absorbed water in affecting glass structure and stability has also been considered. We defined the term "structure" to indicate the way the various molecules in a glass interact with each other and form distinctive molecular arrangements as regions or domains of varying number of molecules, molecular packing, and density. Evidence is presented to suggest that such systems generally exist as heterogeneous structures made up of high-density domains surrounded by a lower density arrangement of molecules, termed the microstructure. It has been shown that the method of preparation and the time frame for handling and storage can give rise to variable glass structures and varying physical properties. Throughout this paper, examples are given of theoretical, computer simulation, and experimental studies which focus on the nature of intermolecular interactions, the size of heterogeneous higher density domains, and the impact of such systems on the relative physical and chemical stability of pharmaceutical systems.
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Affiliation(s)
- George Zografi
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, United States
| | - Ann Newman
- Seventh Street Development Group LLC, Kure Beach, NC, United States.
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2
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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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3
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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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4
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Tournier RF, Ojovan MI. Prediction of Second Melting Temperatures Already Observed in Pure Elements by Molecular Dynamics Simulations. MATERIALS 2021; 14:ma14216509. [PMID: 34772033 PMCID: PMC8585396 DOI: 10.3390/ma14216509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/19/2021] [Accepted: 10/26/2021] [Indexed: 12/01/2022]
Abstract
A second melting temperature occurs at a temperature Tn+ higher than Tm in glass-forming melts after heating them from their glassy state. The melting entropy is reduced or increased depending on the thermal history and on the presence of antibonds or bonds up to Tn+. Recent MD simulations show full melting at Tn+ = 1.119Tm for Zr, 1.126Tm for Ag, 1.219Tm for Fe and 1.354Tm for Cu. The non-classical homogeneous nucleation model applied to liquid elements is based on the increase of the Lindemann coefficient with the heating rate. The glass transition at Tg and the nucleation temperatures TnG of glacial phases are successfully predicted below and above Tm. The glass transition temperature Tg increases with the heating rate up to Tn+. Melting and crystallization of glacial phases occur with entropy and enthalpy reductions. A universal law relating Tn+ and TnG around Tm shows that TnG cannot be higher than 1.293Tm for Tn+= 1.47Tm. The enthalpies and entropies of glacial phases have singular values, corresponding to the increase of percolation thresholds with Tg and TnG above the Scher and Zallen invariant at various heating and cooling rates. The G-phases are metastable up to Tn+ because the antibonds are broken by homogeneous nucleation of bonds.
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Affiliation(s)
- Robert F. Tournier
- UPR 3228 Centre National de la Recherche Scientifique, Laboratoire National des Champs Magnétiques Intenses, European Magnetic Field Laboratory, Institut National des Sciences Appliquées de Toulouse, Université Grenoble Alpes, F-31400 Toulouse, France
- Correspondence:
| | - Michael I. Ojovan
- Department of Materials, Imperial College London, London SW7 2AZ, UK;
- Department of Radiochemistry, Moscow State University, 119991 Moscow, Russia
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5
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Beasley MS, Kasting BJ, Tracy ME, Guiseppi-Elie A, Richert R, Ediger MD. Physical vapor deposition of a polyamorphic system: Triphenyl phosphite. J Chem Phys 2020; 153:124511. [PMID: 33003706 DOI: 10.1063/5.0019872] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In situ AC nanocalorimetry and dielectric spectroscopy were used to analyze films of vapor-deposited triphenyl phosphite. The goal of this work was to investigate the properties of vapor-deposited glasses of this known polyamorphic system and to determine which liquid is formed when the glass is heated. We find that triphenyl phosphite forms a kinetically stable glass when prepared at substrate temperatures of 0.75-0.95Tg, where Tg is the glass transition temperature. Regardless of the substrate temperature utilized during deposition of triphenyl phosphite, heating a vapor-deposited glass always forms the ordinary supercooled liquid (liquid 1). The identity of liquid 1 was confirmed by both the calorimetric signal and the shape and position of the dielectric spectra. For the purposes of comparison, the glacial phase of triphenyl phosphite (liquid 2) was prepared by the conventional method of annealing liquid 1. We speculate that these new results and previous work on vapor deposition of other polyamorphic systems can be explained by the free surface structure being similar to one polyamorph even in a temperature regime where the other polyamorph is more thermodynamically stable in the bulk.
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Affiliation(s)
- M S Beasley
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - B J Kasting
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M E Tracy
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Guiseppi-Elie
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, 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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6
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Beasley MS, Bishop C, Kasting BJ, Ediger MD. Vapor-Deposited Ethylbenzene Glasses Approach "Ideal Glass" Density. J Phys Chem Lett 2019; 10:4069-4075. [PMID: 31269793 DOI: 10.1021/acs.jpclett.9b01508] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Spectroscopic ellipsometry was used to characterize vapor-deposited glasses of ethylbenzene (Tg = 115.7 K). For this system, previous calorimetric experiments have established that a transition to the ideal glass state is expected to occur near 101 K (the Kauzmann temperature, TK) if the low-temperature supercooled liquid has the properties expected based upon extrapolation from above Tg. Ethylbenzene glasses were vapor-deposited at substrate temperatures between 100 (∼0.86 Tg) and 116 K (∼Tg), using deposition rates of 0.02-2.1 nm/s. Down to 103 K, glasses prepared in the limit of low deposition rate have densities consistent with the extrapolated supercooled liquid. The highest density glass is within 0.15% of the density expected for the ideal glass. These results support the hypothesis that the extrapolated properties of supercooled ethylbenzene are correct to within just a few Kelvin of TK, consistent with the existence of a phase transition to an ideal glass state at TK.
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Affiliation(s)
- M S Beasley
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - C Bishop
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - B J Kasting
- 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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7
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Riechers B, Guiseppi-Elie A, Ediger MD, Richert R. Ultrastable and polyamorphic states of vapor-deposited 2-methyltetrahydrofuran. J Chem Phys 2019; 150:214502. [DOI: 10.1063/1.5091796] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] 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 53705, USA
| | - Ranko Richert
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, USA
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8
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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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9
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Beasley MS, Tylinski M, Chua YZ, Schick C, Ediger MD. Glasses of three alkyl phosphates show a range of kinetic stabilities when prepared by physical vapor deposition. J Chem Phys 2018; 148:174503. [DOI: 10.1063/1.5026505] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- M. S. Beasley
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M. Tylinski
- Department of Chemistry, Widener University, Chester, Pennsylvania 19013, USA
| | - Y. Z. Chua
- Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18051 Rostock, Germany and Competence Center CALOR, Faculty of Interdisciplinary Research, University of Rostock, Albert-Einstein-Str. 25, 18051 Rostock, Germany
| | - C. Schick
- Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18051 Rostock, Germany and Competence Center 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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10
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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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11
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Ngai KL, Wang LM, Yu HB. Relating Ultrastable Glass Formation to Enhanced Surface Diffusion via the Johari-Goldstein β-Relaxation in Molecular Glasses. J Phys Chem Lett 2017; 8:2739-2744. [PMID: 28585827 DOI: 10.1021/acs.jpclett.7b01192] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Glasses are materials essential for modern technology; they are usually prepared by cooling liquids. Recently, novel ultrastable glasses (SGs) with extraordinary thermodynamic and kinetic stability have been created by vapor deposition at appropriate substrate temperatures. However, the underlying mechanism for the formation of SGs is still not established. For most of the molecular SGs created so far, we demonstrate that the formation of SGs is closely related to the Johari-Goldstein β-relaxation from the fact that the lowest substrate temperatures possible for the formation of SGs match the secondary glass-transition temperatures, where the β-relaxation time reaches 103 s. Theoretically the β-relaxation time via the primitive relaxation time of the coupling model has proven capable of accounting for the enhancement of molecular mobility at the surface. Thus our findings provide evidence to support that the immense enhancement of molecular diffusion at the surface is critical for the formation of SGs. The result has implications in the design and fabrication of SGs.
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Affiliation(s)
- K L Ngai
- CNR-IPCF, Universita di Pisa , Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University , Qinhuangdao, Hebei 066004, China
| | - Li-Min Wang
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University , Qinhuangdao, Hebei 066004, China
| | - Hai-Bin Yu
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , WuHan, Hubei 430074, China
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12
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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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13
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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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14
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Helfferich J, Lyubimov I, Reid D, de Pablo JJ. Inherent structure energy is a good indicator of molecular mobility in glasses. SOFT MATTER 2016; 12:5898-5904. [PMID: 27334679 DOI: 10.1039/c6sm00810k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Glasses produced via physical vapor deposition can display greater kinetic stability and lower enthalpy than glasses prepared by liquid cooling. While the reduced enthalpy has often been used as a measure of the stability, it is not obvious whether dynamic measures of stability provide the same view. Here, we study dynamics in vapor-deposited and liquid-cooled glass films using molecular simulations of a bead-spring polymer model as well as a Lennard-Jones binary mixture in two and three dimensions. We confirm that the dynamics in vapor-deposited glasses is indeed slower than in ordinary glasses. We further show that the inherent structure energy is a good reporter of local dynamics, and that aged systems and glasses prepared by cooling at progressively slower rates exhibit the same behavior as vapor-deposited materials when they both have the same inherent structure energy. These findings suggest that the stability inferred from measurements of the energy is also manifested in dynamic observables, and they strengthen the view that vapor deposition processes provide an effective strategy for creation of stable glasses.
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Affiliation(s)
- Julian Helfferich
- Institute for Molecular Engineering, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA.
| | - Ivan Lyubimov
- Institute for Molecular Engineering, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA.
| | - Daniel Reid
- Institute for Molecular Engineering, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA.
| | - Juan J de Pablo
- Institute for Molecular Engineering, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA. and Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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15
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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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16
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Liu T, Cheng K, Salami-Ranjbaran E, Gao F, Li C, Tong X, Lin YC, Zhang Y, Zhang W, Klinge L, Walsh PJ, Fakhraai Z. The effect of chemical structure on the stability of physical vapor deposited glasses of 1,3,5-triarylbenzene. J Chem Phys 2016; 143:084506. [PMID: 26328855 DOI: 10.1063/1.4928521] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We detail the formation and properties associated with stable glasses (SG) formed by a series of structural analogues of 1,3-bis(1-naphthyl)-5-(2-naphthyl)benzene (α,α,β-TNB), a well-studied SG former. Five compounds with similar structural properties were synthesized and physical vapor-deposited with a constant deposition rate at various substrate temperatures (Tdep) in the range between 0.73 Tg and 0.96 Tg. These molecules include α,α,β-TNB, 3,5-di(naphthalen-1-yl)-1-phenylbenzene (α,α-P), 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene (α,α-A), 9,9'-(5-(naphthalen-2-yl)-1,3-phenylene)dianthracene (β-AA), and 3,3',5,5'-tetra(naphthalen-1-yl)-1,1'-biphenyl (α,α,α,α-TNBP). Ellipsometry was used to study the transformations from the as-deposited glasses into ordinary glasses (OG). The stability of each film was evaluated by measuring the fictive temperature (Tf) and density difference between the as-deposited glass and OG. It is demonstrated that all five molecules can form SGs upon vapor deposition in this temperature range. In-depth studies on the dependence of the stability of as-deposited glasses upon Tdep were performed with three molecules, α,α,β-TNB, α,α-P, and α,α-A. The general trends of stability were comparable at the same Tdep/Tg for these three compounds. Similar to previous studies on α,α,β-TNB, vapor-deposited glasses of α,α-P and α,α-A formed the most stable structures around Tdep = 0.8-0.85 Tg. The most stable glass of each molecule showed the lowest thermal expansion coefficient compared to OG and a positive optical birefringence. However, the SGs of α,α-A were less stable compared to α,α-P and α,α,β-TNB at the relative Tdep/Tg. Based on Arrhenius extrapolation of the aging time, as a measure of stability, the most stable α,α-A glass was only aged for a few years as opposed to hundreds or thousands of years for other glasses. We hypothesize that the reduced stability is due to slower mobility at the free surface of α,α-A glass compared to the other two molecules.
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Affiliation(s)
- Tianyi Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Kevin Cheng
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Elmira Salami-Ranjbaran
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Feng Gao
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Chen Li
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Xiao Tong
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Yi-Chih Lin
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Yue Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - William Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Lindsey Klinge
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Patrick J Walsh
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Zahra Fakhraai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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17
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Kasina A, Putzeys T, Wübbenhorst M. Dielectric and specific heat relaxations in vapor deposited glycerol. J Chem Phys 2015; 143:244504. [PMID: 26723689 DOI: 10.1063/1.4937795] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Recently [S. Capponi, S. Napolitano, and M. Wübbenhorst, Nat. Commun. 3, 1233 (2012)], vapor deposited glasses of glycerol have been found to recover their super-cooled liquid state via a metastable, ordered liquid (MROL) state characterized by a tremendously enhanced dielectric strength along with a slow-down of the relaxation rate of the structural relaxation. To study the calorimetric signature of this phenomenon, we have implemented a chip-based, differential AC calorimeter in an organic molecular beam deposition setup, which allows the simultaneous measurement of dielectric relaxations via interdigitated comb electrodes and specific heat relaxation spectra during deposition and as function of the temperature. Heating of the as-deposited glass just above the bulk Tg and subsequent cooling/reheating revealed a step-wise increase in cp by in total 9%, indicating unambiguously that glycerol, through slow vapour deposition, forms a thermodynamically stable glass, which has a specific heat as low as that of crystalline glycerol. Moreover, these glasses were found to show excellent kinetic stability as well as evidenced by both a high onset-temperature and quasi-isothermal recovery measurements at -75 °C. The second goal of the study was to elucidate the impact of the MROL state on the specific heat and its relaxation to the super-cooled state. Conversion of "MROL glycerol" to its "normal" (ordinary liquid, OL) state revealed a second, small (∼2%) increase of the glassy cp, a little gain (<10%) in the relaxed specific heat, and no signs of deviations of τcal from that of normal "bulk" glycerol. These findings altogether suggest that the MROL state in glycerol comprises largely bulk-type glycerol that coexist with a minor volume fraction (<10%) of PVD-induced structural anomalies with a crystal-like calorimetric signature. Based on the new calorimetric findings, we have proposed a new physical picture that assumes the existence of rigid polar clusters (RPCs) and conclusively explains the extraordinary high kinetic stability of the MROL state, its specific calorimetric signature, the enhanced strength, and apparent slow-down of the dielectric α-relaxation. In this new picture, the incredibly slow and strengthened dielectric response is ascribed to driven rotational diffusion of whole RPCs, a mechanism that perfectly couples to the relaxation time of the "normal" glycerol fraction. First considerations based on the strength and the retardation of the dielectric RPCs' response yield independently a size estimate for the RPCs in the order of 4-5 nm. Finally, we have discussed possible crystallisation and reorganisation effects, which give rise to pronounced out-of phase components of the specific heat at higher temperatures.
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Affiliation(s)
- A Kasina
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven, Leuven, Belgium
| | - T Putzeys
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven, Leuven, Belgium
| | - M Wübbenhorst
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven, Leuven, Belgium
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18
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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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19
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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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20
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Smith RS, May RA, Kay BD. Probing Toluene and Ethylbenzene Stable Glass Formation Using Inert Gas Permeation. J Phys Chem Lett 2015; 6:3639-3644. [PMID: 26722735 DOI: 10.1021/acs.jpclett.5b01611] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Inert gas permeation is used to investigate the formation of stable glasses of toluene and ethylbenzene. The effect of deposition temperature (T(dep)) on the kinetic stability of the vapor deposited glasses is determined using Kr desorption spectra from within sandwich layers of either toluene or ethylbenzene. The results for toluene show that the most stable glass is formed at T(dep) = 0.92 T(g), although glasses with a kinetic stability within 50% of the most stable glass were found with deposition temperatures from 0.85 to 0.95 T(g). Similar results were found for ethylbenzene, which formed its most stable glass at 0.91 T(g) and formed stable glasses from 0.81 to 0.96 T(g). These results are consistent with recent calorimetric studies and demonstrate that the inert gas permeation technique provides a direct method to observe the onset of molecular translation motion that accompanies the glass to supercooled liquid transition.
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Affiliation(s)
- R Scott Smith
- Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - R Alan May
- Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Bruce D Kay
- Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
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21
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Whitaker KR, Tylinski M, Ahrenberg M, Schick C, Ediger MD. Kinetic stability and heat capacity of vapor-deposited glasses of o-terphenyl. J Chem Phys 2015; 143:084511. [DOI: 10.1063/1.4929511] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Katherine R. Whitaker
- Department of Mathematics and Physical Sciences, Louisiana State University of Alexandria, Alexandria, Louisiana 71302, USA
| | - M. Tylinski
- Department of Chemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706, USA
| | | | - Christoph Schick
- Institute of Physics, University of Rostock, Rostock 18051, Germany
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706, USA
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22
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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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23
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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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24
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L. M. Ramos SL, Chigira AK, Oguni M. Devitrification Properties of Vapor-Deposited Ethylcyclohexane Glasses and Interpretation of the Molecular Mechanism for Formation of Vapor-Deposited Glasses. J Phys Chem B 2015; 119:4076-83. [DOI: 10.1021/jp5109174] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Sergio Luis L. M. Ramos
- Department of Chemistry, Graduate School
of Science and Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Atsuko. K. Chigira
- Department of Chemistry, Graduate School
of Science and Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Masaharu Oguni
- Department of Chemistry, Graduate School
of Science and Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
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25
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Shepard KB, Arnold CB, Priestley RD. Transport and Stability of Laser-Deposited Amorphous Polymer Nanoglobules. ACS Macro Lett 2014; 3:1046-1050. [PMID: 35610790 DOI: 10.1021/mz500546u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We characterized the transport, i.e., time-of-flight, and nanoscale thermal properties of amorphous polymer nanoglobules fabricated via a laser-deposition technique, Matrix-Assisted Pulsed Laser Deposition (MAPLE). Here, we report the first experimental measurement of the velocity of polymer during MAPLE processing and its connection to nanostructured film formation. A nanoscale dilatometry technique using atomic force microscopy was employed to directly measure the thermal properties of MAPLE-deposited polymer nanoglobules. Similarly to bulk stable polymer glasses deposited by MAPLE, polymer nanoglobules were found to exhibit enhanced thermal stability and low density despite containing only thousands of molecules. By directly connecting the exceptional properties of the nanostructured building blocks to those of bulk stable glasses, we gain insight into the physics of glassy polymeric materials formed via vapor-assisted techniques.
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Affiliation(s)
- Kimberly B. Shepard
- Chemical and Biological Engineering, ‡Mechanical and Aerospace Engineering, §Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
| | - Craig B. Arnold
- Chemical and Biological Engineering, ‡Mechanical and Aerospace Engineering, §Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
| | - Rodney D. Priestley
- Chemical and Biological Engineering, ‡Mechanical and Aerospace Engineering, §Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
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26
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Tripathi P, Gonzalo-Ruiz J, Mitsari E, Zachariah M, Romanini M, Tamarit JL, Muñoz FX, Macovez R. Silicon-Chip-Based Dielectric Spectroscopy for Conductivity and Molecular Dynamics Studies of Organic Films. J Phys Chem Lett 2014; 5:2796-2801. [PMID: 26278081 DOI: 10.1021/jz501119a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Interdigital electrodes fabricated by standard lithography on silicon chips are employed to probe the dipolar molecular dynamics and electric conduction properties of thin rhodamine films grown with two different methods. The conductivity is due to electronic charge carriers, and at around room-temperature, it is higher by 1 order of magnitude in solution-deposited films than in thermally evaporated ones. The organic material exhibits two intrinsic dynamic processes, of which the one at higher temperature is due to the orientational motion of the dipole moment of the rhodamine units, while the one at lower temperature is due to the motion of a local dipole associated with the chlorine counterions and is absent in thermally evaporated films. Our results show that thin-film dielectric spectroscopy is an easily implementable and versatile tool to extract valuable information on thin organic films.
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Affiliation(s)
- Pragya Tripathi
- †Grup de Caracterització de Materials, Departament de Fı́sica i Enginyieria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain
| | | | - Efstratia Mitsari
- †Grup de Caracterització de Materials, Departament de Fı́sica i Enginyieria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain
| | - Manesh Zachariah
- †Grup de Caracterització de Materials, Departament de Fı́sica i Enginyieria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain
| | - Michela Romanini
- †Grup de Caracterització de Materials, Departament de Fı́sica i Enginyieria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain
| | - Josep Lluis Tamarit
- †Grup de Caracterització de Materials, Departament de Fı́sica i Enginyieria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain
| | | | - Roberto Macovez
- †Grup de Caracterització de Materials, Departament de Fı́sica i Enginyieria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain
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27
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Vapor-deposited glasses provide clearer view of two-level systems. Proc Natl Acad Sci U S A 2014; 111:11232-3. [PMID: 25053809 DOI: 10.1073/pnas.1411278111] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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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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29
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Haji-Akbari A, Debenedetti PG. The effect of substrate on thermodynamic and kinetic anisotropies in atomic thin films. J Chem Phys 2014; 141:024506. [DOI: 10.1063/1.4885365] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Amir Haji-Akbari
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Pablo G. Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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30
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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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