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Hartley AD, Drayer WF, Ghanekarade A, Simmons DS. Interplay between dynamic heterogeneity and interfacial gradients in a model polymer film. J Chem Phys 2023; 159:204905. [PMID: 38032012 DOI: 10.1063/5.0165650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Glass-forming liquids exhibit long-lived, spatially correlated dynamical heterogeneity, in which some nm-scale regions in the fluid relax more slowly than others. In the nanoscale vicinity of an interface, glass-formers also exhibit the emergence of massive interfacial gradients in glass transition temperature Tg and relaxation time τ. Both of these forms of heterogeneity have a major impact on material properties. Nevertheless, their interplay has remained poorly understood. Here, we employ molecular dynamics simulations of polymer thin films in the isoconfigurational ensemble in order to probe how bulk dynamic heterogeneity alters and is altered by the large gradient in dynamics at the surface of a glass-forming liquid. Results indicate that the τ spectrum at the surface is broader than in the bulk despite being shifted to shorter times, and yet it is less spatially correlated. This is distinct from the bulk, where the τ distribution becomes broader and more spatially organized as the mean τ increases. We also find that surface gradients in slow dynamics extend further into the film than those in fast dynamics-a result with implications for how distinct properties are perturbed near an interface. None of these features track locally with changes in the heterogeneity of caging scale, emphasizing the local disconnect between these quantities near interfaces. These results are at odds with conceptions of the surface as reflecting simply a higher "rheological temperature" than the bulk, instead pointing to a complex interplay between bulk dynamic heterogeneity and spatially organized dynamical gradients at interfaces in glass-forming liquids.
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Affiliation(s)
- Austin D Hartley
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - William F Drayer
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - Asieh Ghanekarade
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - David S Simmons
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
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Li B, Zhang S, Andre JS, Chen Z. Relaxation behavior of polymer thin films: Effects of free surface, buried interface, and geometrical confinement. Prog Polym Sci 2021; 120:101431. [DOI: 10.1016/j.progpolymsci.2021.101431] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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3
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Diaz Vela D, Simmons DS. The microscopic origins of stretched exponential relaxation in two model glass-forming liquids as probed by simulations in the isoconfigurational ensemble. J Chem Phys 2020; 153:234503. [PMID: 33353315 DOI: 10.1063/5.0035609] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The origin of stretched exponential relaxation in supercooled glass-forming liquids is one of the central questions regarding the anomalous dynamics of these fluids. The dominant explanation for this phenomenon has long been the proposition that spatial averaging over a heterogeneous distribution of locally exponential relaxation processes leads to stretching. Here, we perform simulations of model polymeric and small-molecule glass-formers in the isoconfigurational ensemble to show that stretching instead emerges from a combination of spatial averaging and locally nonexponential relaxation. The results indicate that localities in the fluid exhibiting faster-than-average relaxation tend to exhibit locally stretched relaxation, whereas slower-than-average relaxing domains exhibit more compressed relaxation. We show that local stretching is predicted by loose local caging, as measured by the Debye-Waller factor, and vice versa. This phenomenology in the local relaxation of in-equilibrium glasses parallels the dynamics of out of equilibrium under-dense and over-dense glasses, which likewise exhibit an asymmetry in their degree of stretching vs compression. On the basis of these results, we hypothesize that local stretching and compression in equilibrium glass-forming liquids results from evolution of particle mobilities over a single local relaxation time, with slower particles tending toward acceleration and vice versa. In addition to providing new insight into the origins of stretched relaxation, these results have implications for the interpretation of stretching exponents as measured via metrologies such as dielectric spectroscopy: measured stretching exponents cannot universally be interpreted as a direct measure of the breadth of an underlying distribution of relaxation times.
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Affiliation(s)
- Daniel Diaz Vela
- Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, Florida 33620, USA
| | - David S Simmons
- Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, Florida 33620, USA
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4
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Affiliation(s)
- Amber N. Storey
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, United States
| | - Wengang Zhang
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, United States
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Francis W. Starr
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, United States
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Hasan N, Busse K, Haider T, Wurm FR, Kressler J. Crystallization of Poly(ethylene)s with Regular Phosphoester Defects Studied at the Air-Water Interface. Polymers (Basel) 2020; 12:E2408. [PMID: 33086637 PMCID: PMC7650800 DOI: 10.3390/polym12102408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/14/2020] [Accepted: 10/16/2020] [Indexed: 11/16/2022] Open
Abstract
Poly(ethylene) (PE) is a commonly used semi-crystalline polymer which, due to the lack of polar groups in the repeating unit, is not able to form Langmuir or Langmuir-Blodgett (LB) films. This problem can be solved using PEs with hydrophilic groups arranged at regular distances within the polymer backbone. With acyclic diene metathesis (ADMET) polymerization, a tool for precise addition of polar groups after a certain interval of methylene sequence is available. In this study, we demonstrate the formation of Langmuir/LB films from two different PEs with regular phosphoester groups, acting as crystallization defects in the main chain. After spreading the polymers from chloroform solution on the water surface of a Langmuir trough and solvent evaporation, the surface pressure is recorded during compression under isothermal condition. These π-A isotherms, surface pressure π vs. mean area per repeat unit A, show a plateau zone at surface pressures of ~ (6 to 8) mN/m, attributed to the formation of crystalline domains of the PEs as confirmed by Brewster angle and epifluorescence microscopy. PE with ethoxy phosphoester defects (Ethoxy-PPE) forms circular shape domains, whereas Methyl-PPE-co-decadiene with methyl phosphoester defects and two different methylene sequences between the defects exhibits a film-like morphology. The domains/films are examined by atomic force microscopy after transferring them to a solid support. The thickness of the domains/films is found in the range from ~ (2.4 to 3.2) nm depending on the transfer pressure. A necessity of chain tilt in the crystalline domains is also confirmed. Grazing incidence X-ray scattering measurements in LB films show a single Bragg reflection at a scattering vector qxy position of ~ 15.1 nm-1 known from crystalline PE samples.
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Affiliation(s)
- Nazmul Hasan
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, D-06099 Halle, Germany; (N.H.); (K.B.)
| | - Karsten Busse
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, D-06099 Halle, Germany; (N.H.); (K.B.)
| | - Tobias Haider
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany;
| | - Frederik R. Wurm
- Sustainable Polymer Chemistry Group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, Universiteit Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands;
| | - Jörg Kressler
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, D-06099 Halle, Germany; (N.H.); (K.B.)
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6
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Soles CL, Burns AB, Ito K, Chan E, Liu J, Yee AF, Tyagi MS. Importance of Sub-Nanosecond Fluctuations on the Toughness of Polycarbonate Glasses. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00857] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christopher L. Soles
- NIST Materials Science and Engineering Division, 100 Bureau Drive, Gaithersburg 20899, Maryland, United States
| | - Adam B. Burns
- NIST Materials Science and Engineering Division, 100 Bureau Drive, Gaithersburg 20899, Maryland, United States
| | - Kanae Ito
- NIST Materials Science and Engineering Division, 100 Bureau Drive, Gaithersburg 20899, Maryland, United States
| | - Edwin Chan
- NIST Materials Science and Engineering Division, 100 Bureau Drive, Gaithersburg 20899, Maryland, United States
| | - Jianwei Liu
- Macromolecular Science and Engineering, University of Michigan, Ann Arbor 48109, Michigan, United States
| | - Albert F. Yee
- Department of Chemical and Biological Engineering, University of California, Irvine 92697, California, United States
| | - Madhu Sudan Tyagi
- NIST Center for Neutron Research, 100 Bureau Drive, Gaithersburg 20899, Maryland, United States
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Abstract
We propose a phenomenological model to describe the equilibrium dynamic behavior of amorphous glassy materials. It is assumed that a material can be represented by a lattice of cooperatively re-arranging regions (CRRs), with each CRR having two states, the low-temperature "solid" and the high-temperature "liquid". At low temperatures, the material exhibits two characteristic relaxation times, corresponding to the slow large-scale motion between the "solid" CRRs (α-relaxation) and the faster local motion within individual CRRs (β-relaxation). At high temperatures, the α- and β-relaxation times merge, as observed experimentally and suggested by the "Coupling Model" framework. Our new approach is labeled "Two-state, two (time)scale model" or TS2. It is shown that the TS2 treatment can successfully describe the "two-Arrhenius" relaxation time behavior described in several recent experiments. We also apply TS2 to describe the pressure- and molecular-weight dependence of the glass transition temperature in bulk polymers, as well as its dependence on film thickness in thin films.
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Affiliation(s)
- Valeriy V Ginzburg
- Core Research and Development, The Dow Chemical Company, Midland, MI 48674, USA.
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8
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Affiliation(s)
- Masoud Razavi
- Department of Polymer Science, University of Akron, Akron, Ohio 44325, United States
| | - Da Huang
- Department of Polymer Science, University of Akron, Akron, Ohio 44325, United States
| | - Suqi Liu
- Department of Polymer Science, University of Akron, Akron, Ohio 44325, United States
| | - Hailan Guo
- The Dow Chemical Company, Collegeville, Pennsylvania 19426, United States
| | - Shi-Qing Wang
- Department of Polymer Science, University of Akron, Akron, Ohio 44325, United States
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9
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Owusu-Ware SK, Boateng JS, Chowdhry BZ, Antonijevic MD. Glassy state molecular mobility and its relationship to the physico-mechanical properties of plasticized hydroxypropyl methylcellulose (HPMC) films. Int J Pharm X 2019; 1:100033. [PMID: 31528853 PMCID: PMC6744590 DOI: 10.1016/j.ijpx.2019.100033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/20/2019] [Accepted: 08/21/2019] [Indexed: 12/02/2022] Open
Abstract
Changes in tensile properties and the glass transition temperature (Tg) of plasticized polymer films are typically attributed to molecular mobility, often with no empirical data to support such an assertion. Herein solvent cast HPMC films containing varying amounts of PEG, as the plasticizer, were used to assess the dependence of tensile properties and the Tg on glassy state molecular mobility. Molecular mobility (molecular relaxation time and temperature) parameters were determined by Thermally Stimulated Current Spectroscopy (TSC). The tensile properties and Tg of the HPMC films were determined by texture analysis and DSC, respectively. Molecular mobilities detected by TSC were cooperative and occurred at temperatures (Tg′) well below (113 to 127 °C) the bulk Tg. The relaxation times (τ) were 71 ± 1, 46 ± 1, 42 ± 1, 36 ± 1 and 29 ± 1 s for HPMC films containing 0, 6, 8, 11 and 17% (w/w) PEG, respectively. The Tg and glassy state molecular mobility were found to be intimately linked and demonstrated a linear dependence. While tensile strength was found to be linearly related to molecular relaxation time, tensile elongation and elastic modulus exhibited a non-linear dependence on molecular mobility. The data presented in this work demonstrates the complex nature of the relationship between plasticizer content, molecular mobility, Tg and tensile properties for plasticized polymeric films. It highlights the fact that the dependence of the bulk physico-mechanical properties on glassy state molecular mobility, differ greatly. Therefore, empirical characterization of molecular mobility is important to fully understand and predict the thermo-mechanical behavior of plasticized polymer films. This work demonstrates the unique capability of TSC to provide key information relating to molecular mobility and its influence on the bulk properties of materials. Data generated using TSC could prove useful for stability and performance ranking, in addition to the ability to predict materials behavior using data generated at or below typical storage conditions in the pharmaceutical, food, and polymer industries.
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Affiliation(s)
| | - Joshua S. Boateng
- School of Science, Faculty of Engineering and Science, University of Greenwich (Medway Campus), Chatham Maritime, Kent ME4 4TB, UK
| | - Babur Z. Chowdhry
- School of Science, Faculty of Engineering and Science, University of Greenwich (Medway Campus), Chatham Maritime, Kent ME4 4TB, UK
| | - Milan D. Antonijevic
- School of Science, Faculty of Engineering and Science, University of Greenwich (Medway Campus), Chatham Maritime, Kent ME4 4TB, UK
- Corresponding authors.
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10
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Affiliation(s)
- Eric J. Bailey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Philip J. Griffin
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Madhusudan Tyagi
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Karen I. Winey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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11
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Zhang W, Douglas JF, Starr FW. Why we need to look beyond the glass transition temperature to characterize the dynamics of thin supported polymer films. Proc Natl Acad Sci U S A 2018; 115:5641-5646. [PMID: 29760090 PMCID: PMC5984511 DOI: 10.1073/pnas.1722024115] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
There is significant variation in the reported magnitude and even the sign of [Formula: see text] shifts in thin polymer films with nominally the same chemistry, film thickness, and supporting substrate. The implicit assumption is that methods used to estimate [Formula: see text] in bulk materials are relevant for inferring dynamic changes in thin films. To test the validity of this assumption, we perform molecular simulations of a coarse-grained polymer melt supported on an attractive substrate. As observed in many experiments, we find that [Formula: see text] based on thermodynamic criteria (temperature dependence of film height or enthalpy) decreases with decreasing film thickness, regardless of the polymer-substrate interaction strength ε. In contrast, we find that [Formula: see text] based on a dynamic criterion (relaxation of the dynamic structure factor) also decreases with decreasing thickness when ε is relatively weak, but [Formula: see text] increases when ε exceeds the polymer-polymer interaction strength. We show that these qualitatively different trends in [Formula: see text] reflect differing sensitivities to the mobility gradient across the film. Apparently, the slowly relaxing polymer segments in the substrate region make the largest contribution to the shift of [Formula: see text] in the dynamic measurement, but this part of the film contributes less to the thermodynamic estimate of [Formula: see text] Our results emphasize the limitations of using [Formula: see text] to infer changes in the dynamics of polymer thin films. However, we show that the thermodynamic and dynamic estimates of [Formula: see text] can be combined to predict local changes in [Formula: see text] near the substrate, providing a simple method to infer information about the mobility gradient.
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Affiliation(s)
- Wengang Zhang
- Department of Physics, Wesleyan University, Middletown, CT 06459
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Francis W Starr
- Department of Physics, Wesleyan University, Middletown, CT 06459;
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12
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Inoue R, Kanaya T, Yamada T, Shibata K, Fukao K. Experimental investigation of the glass transition of polystyrene thin films in a broad frequency range. Phys Rev E 2018; 97:012501. [PMID: 29448351 DOI: 10.1103/physreve.97.012501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Indexed: 11/07/2022]
Abstract
In this study, we investigate the α process of a polystyrene thin film using inelastic neutron scattering (INS), dielectric relaxation spectroscopy (DRS), and thermal expansion spectroscopy (TES). The DRS and TES measurements exhibited a decrease in glass transition temperature (T_{g}) with film thickness. On the other hand, an increase in T_{g} was observed in INS studies. In order to interpret this contradiction, we investigated the temperature dependence of the peak frequency (f_{m}) of the α process probed by DRS and TES. The experiments revealed an increase in the peak frequency (f_{m}) with decreasing film thickness in the frequency region. This observation is consistent with the observed decrease in T_{g} with thickness. Interestingly, the increase in T_{g} with film thickness was confirmed by fitting the temperature dependence measurements of the peak frequency with the Vogel-Fulcher-Tammann equation, within the frequency region probed by INS. The discrepancy between INS and DRS or TES descriptions of the α process is likely to be attributed to a decrease in the apparent activation energy with film thickness and reduced mobility, due to the impenetrable wall effect.
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Affiliation(s)
- Rintaro Inoue
- Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Toshiji Kanaya
- J-PARC, Material and Life Science Division, Institute of Material Structure Science, High Energy Accelerator Research Organization (KEK), 203-1 Shirakata, Tokai-mura, Naka-gun, Ibaraki, 319-1106, Japan
| | - Takeshi Yamada
- CROSS-Tokai, Research Center for Neutron Science and Technology, Tokai, Ibaraki 319-1106, Japan
| | - Kaoru Shibata
- Neutron Science Section, J-PARC Center, Tokai, Ibaraki 319-1195, Japan
| | - Koji Fukao
- Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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13
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Affiliation(s)
- Bryan D. Vogt
- Department of Polymer Engineering; University of Akron; Akron Ohio 44325
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14
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Hori K, Yamada NL, Fujii Y, Masui T, Kishimoto H, Seto H. Structure and Mechanical Properties of Polybutadiene Thin Films Bound to Surface-Modified Carbon Interface. Langmuir 2017; 33:8883-8890. [PMID: 28799335 DOI: 10.1021/acs.langmuir.7b01457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The structure and mechanical properties of polybutadiene (PB) films on bare and surface-modified carbon films were examined. There was an interfacial layer of PB near the carbon layer whose density was higher (lower) than that of the bulk material on the hydrophobic (hydrophilic) carbon surface. To glean information about the structure and mechanical properties of PB at the carbon interface, a residual layer (RL) adhering to the carbon surface, which was considered to be a model of "bound rubber layer", was obtained by rinsing the PB film with toluene. The density and thickness of the RLs were identical to those of the interfacial layer of the PB film. In accordance with the change in the density, normal stress of the RLs evaluated by atomic force microscopy was also dependent on the surface free energy: the RLs on the hydrophobic carbon were hard like glass, whereas those on the hydrophilic carbon were soft like rubber. Similarly, the wear test revealed that the RLs on the hydrophilic carbon could be peeled off by scratching under a certain stress, whereas the RLs on the hydrophobic carbons were resistant to scratching.
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Affiliation(s)
- Koichiro Hori
- Institute of Materials Structure Science, High Energy Accelerator Research Organization , 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Norifumi L Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization , 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Yoshihisa Fujii
- Department of Chemistry for Materials, Graduate School of Engineering, Mie University , 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan
| | - Tomomi Masui
- Sumitomo Rubber Industries Ltd. , 1-1, 2-chome, Tsutsui-cho, Chuo-ku, Kobe 651-0071, Japan
| | - Hiroyuki Kishimoto
- Sumitomo Rubber Industries Ltd. , 1-1, 2-chome, Tsutsui-cho, Chuo-ku, Kobe 651-0071, Japan
| | - Hideki Seto
- Institute of Materials Structure Science, High Energy Accelerator Research Organization , 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
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Affiliation(s)
- Yuxing Zhou
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Scott T. Milner
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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17
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Affiliation(s)
- Weston L. Merling
- Department
of Polymer Engineering, The University of Akron, 250 South Forge
St., Akron, Ohio 44325-0301, United States
| | - Johnathon B. Mileski
- Department
of Polymer Engineering, The University of Akron, 250 South Forge
St., Akron, Ohio 44325-0301, United States
| | - Jack F. Douglas
- Materials
Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - David S. Simmons
- Department
of Polymer Engineering, The University of Akron, 250 South Forge
St., Akron, Ohio 44325-0301, United States
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18
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Owusu-Ware SK, Boateng J, Jordan D, Portefaix S, Tasseto R, Ramano CD, Antonijević MD. Molecular mobility of hydroxyethyl cellulose (HEC) films characterised by thermally stimulated currents (TSC) spectroscopy. Int J Pharm 2016; 497:222-7. [DOI: 10.1016/j.ijpharm.2015.11.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 11/27/2015] [Accepted: 11/28/2015] [Indexed: 10/22/2022]
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Affiliation(s)
- Tsuyoshi Tsujioka
- Department of Arts and Sciences; Osaka Kyoiku University; Asahigaoka 4-698-2 Kashiwara Osaka 582-8582 Japan
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20
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Udagawa A, Fujie T, Kawamoto Y, Saito A, Takeoka S, Asahi T. Interfacial effects on the crystallization and surface properties of poly(l-lactic acid) ultrathin films. Polym J 2015. [DOI: 10.1038/pj.2015.95] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Affiliation(s)
- K. L. Ngai
- CNR-IPCF, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
- State
Key Lab of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 China
| | - S. Capaccioli
- CNR-IPCF, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
- Dipartimento
di Fisica, Università di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
| | - D. Prevosto
- CNR-IPCF, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
| | - Li-Min Wang
- State
Key Lab of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 China
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22
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Cangialosi D. Effect of Confinement Geometry on Out-of-Equilibrium Glassy Dynamics. In: Napolitano S, editor. Non-equilibrium Phenomena in Confined Soft Matter. Cham: Springer International Publishing; 2015. pp. 265-98. [DOI: 10.1007/978-3-319-21948-6_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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23
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Davris T, Lyulin AV. A coarse-grained molecular dynamics study of segmental structure and mobility in capped crosslinked copolymer films. J Chem Phys 2015; 143:074906. [DOI: 10.1063/1.4928961] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- T. Davris
- Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - A. V. Lyulin
- Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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24
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Kanaya T, Ogawa H, Kishimoto M, Inoue R, Suter A, Prokscha T. Distribution of glass transition temperatures Tg in polystyrene thin films as revealed by low-energy muon spin relaxation: A comparison with neutron reflectivity results. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 92:022604. [PMID: 26382423 DOI: 10.1103/physreve.92.022604] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Indexed: 06/05/2023]
Abstract
In a previous paper [Phys. Rev. E 83, 021801 (2011)] we performed neutron reflectivity (NR) measurements on a five-layer polystyrene (PS) thin film consisting of alternatively stacked deuterated polystyrene (dPS) and hydrogenated polystyrene (hPS) layers (dPS/hPS/dPS/hPS/dPS, ∼100 nm thick) on a Si substrate to reveal the distribution of Tg along the depth direction. Information on the Tg distribution is very useful to understand the interesting but unusual properties of polymer thin films. However, one problem that we have to clarify is if there are effects of deuterium labeling on Tg or not. To tackle the problem we performed low-energy muon spin relaxation (μSR) measurements on the above-mentioned deuterium-labeled five-layer PS thin film as well as dPS and hPS single-layer thin films ∼100 nm thick as a function of muon implantation energy. It was found that the deuterium labeling had no significant effects on the Tg distribution, guaranteeing that we can safely discuss the unusual thin film properties based on the Tg distribution revealed by NR on the deuterium-labeled thin films. In addition, the μSR result suggested that the higher Tg near the Si substrate is due to the strong orientation of phenyl rings.
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Affiliation(s)
- Toshiji Kanaya
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
| | - Hiroki Ogawa
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
| | - Mizuki Kishimoto
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
| | - Rintaro Inoue
- Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka-fu 590-0494, Japan
| | - Andreas Suter
- Laboratory for Muon-Spin Spectroscopy, Swiss Muon Source SµS, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Thomas Prokscha
- Laboratory for Muon-Spin Spectroscopy, Swiss Muon Source SµS, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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25
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Lu XL, Mi YL. Glass transition behavior of spin-coated thin films of a hydrophilic polymer on supported substrates. Chin J Polym Sci 2015. [DOI: 10.1007/s10118-015-1612-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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26
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Ye C, Wiener CG, Tyagi M, Uhrig D, Orski SV, Soles CL, Vogt BD, Simmons DS. Understanding the Decreased Segmental Dynamics of Supported Thin Polymer Films Reported by Incoherent Neutron Scattering. Macromolecules 2015. [DOI: 10.1021/ma501780g] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Changhuai Ye
- Department
of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Clinton G. Wiener
- Department
of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Madhusudan Tyagi
- Department
of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - David Uhrig
- Center
for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | | | | | - Bryan D. Vogt
- Department
of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - David S. Simmons
- Department
of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
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27
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Yang C, Ishimoto K, Matsuura S, Koyasu N, Takahashi I. Depth-dependent inhomogeneous characteristics in supported glassy polystyrene films revealed by ultra-low X-ray reflectivity measurements. Polym J 2014; 46:873-9. [DOI: 10.1038/pj.2014.80] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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28
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Batistakis C, Michels MAJ, Lyulin AV. Confinement-Induced Stiffening of Thin Elastomer Films: Linear and Nonlinear Mechanics vs Local Dynamics. Macromolecules 2014. [DOI: 10.1021/ma5003744] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chrysostomos Batistakis
- Theory
of Polymers and Soft Matter (TPS), Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Dutch Polymer
Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - M. A. J. Michels
- Theory
of Polymers and Soft Matter (TPS), Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Alexey V. Lyulin
- Theory
of Polymers and Soft Matter (TPS), Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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29
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Guseva DV, Komarov PV, Lyulin AV. Molecular-dynamics simulations of thin polyisoprene films confined between amorphous silica substrates. J Chem Phys 2014; 140:114903. [PMID: 24655202 DOI: 10.1063/1.4868231] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- D V Guseva
- Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - P V Komarov
- Department of Theoretical Physics, Tver State University, Sadovyj per. 35, 170002 Tver, Russia and Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova st. 28, 119991 Moscow, Russia
| | - Alexey V Lyulin
- Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
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30
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McKenzie I, Salman Z, Giblin SR, Han YY, Leach GW, Morenzoni E, Prokscha T, Suter A. Polymer dynamics near the surface and in the bulk of poly(tetrafluoroethylene) probed by zero-field muon-spin-relaxation spectroscopy. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:022605. [PMID: 25353500 DOI: 10.1103/physreve.89.022605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Indexed: 06/04/2023]
Abstract
The results of many experiments on polymers such as polystyrene indicate that the polymer chains near a free surface exhibit enhanced dynamics when compared with the bulk. We have investigated whether this is the case for poly(tetrafluoroethylene) (PTFE) by using zero-field muon-spin-relaxation spectroscopy to characterize a local probe, the F-Mu(+)-F state, which forms when spin-polarized positive muons are implanted in PTFE. Low-energy muons (implantation energies from 2.0 to 23.0 keV) were used to study the F-Mu(+)-F state between ∼ 23 and 191 nm from the free surface of PTFE. Measurements were also made with surface muons (4.1 MeV) where the mean implantation depth is on the order of ∼ 0.6 mm. The relaxation rate of the F-Mu(+)-F state up to ∼ 150 K was found to be significantly higher for muons implanted at 2.0 keV than for higher implantation energies, which suggests that the polymer chains in a region on the order of a few tens of nanometers from the free surface are more mobile than those in the bulk.
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Affiliation(s)
- Iain McKenzie
- Centre for Molecular and Materials Science, TRIUMF, Vancouver, British Columbia, Canada V6T 2A3 and Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Zaher Salman
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Sean R Giblin
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, United Kingdom
| | - Yun Yu Han
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Gary W Leach
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Elvezio Morenzoni
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Thomas Prokscha
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Andreas Suter
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
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31
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Inoue R, Nakamura M, Matsui K, Kanaya T, Nishida K, Hino M. Distribution of glass transition temperature in multilayered poly(methyl methacrylate) thin film supported on a Si substrate as studied by neutron reflectivity. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:032601. [PMID: 24125286 DOI: 10.1103/physreve.88.032601] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 05/26/2023]
Abstract
We studied the distribution of glass transition temperature (Tg) through neutron reflectivity in a poly(methyl methacrylate) (PMMA) thin film supported on a silicon substrate with a five-layered PMMA thin film consisting of deuterated-PMMA and hydrogenated-PMMA. The depth distribution of Tg was successfully observed in the PMMA thin film. Compared to the previously reported distribution of Tg in a polystyrene thin film, the presence of a long-range interfacial effect, supposedly caused by an interaction between PMMA and the substrate, is considered to be responsible for the differences in both the distribution of Tg and the thickness dependence of Tg in both polymers. Therefore, it is expected that the thickness dependence of Tg reported for single-layered polymer thin films can, in principle, be understood from the viewpoint of the difference in the depth distribution of Tg.
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Affiliation(s)
- Rintaro Inoue
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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32
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Hoppe ET, Sepe A, Haese-Seiller M, Moulin JF, Papadakis CM. Density profile in thin films of polybutadiene on silicon oxide substrates: a TOF-NR study. Langmuir 2013; 29:10759-10768. [PMID: 23941468 DOI: 10.1021/la402188x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We have investigated thin films from fully deuterated polybutadiene (PB-d6) on silicon substrates with the aim of detecting and characterizing a possible interphase in the polymer film near the substrate using time-of-flight neutron reflectometry (TOF-NR). As substrates, thermally oxidized silicon wafers were either used as such or they were coated with triethylethoxysilyl modified 1,2-PB prior to deposition of the PB-d6 film. TOF-NR reveals that, for both substrates, the scattering length density (SLD) of the PB films decreases near the solid interface. The reduction of SLD is converted to an excess fraction of free volume. To further verify the existence of the interphase in PB-d6, we attempt to model the TOF-NR curves with density profiles which do not feature an interphase. These density profiles do not describe the TOF-NR curves adequately. We conclude that, near the solid interface, an interphase having an SLD lower than the bulk of the film is present.
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Affiliation(s)
- E Tilo Hoppe
- Technische Universität München, Physik-Department, Physik weicher Materie, James-Franck-Str. 1, 85748 Garching, Germany
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33
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34
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Jang C, Lacy TE, Gwaltney SR, Toghiani H, Pittman CU. Interfacial shear strength of cured vinyl ester resin-graphite nanoplatelet from molecular dynamics simulations. POLYMER 2013. [DOI: 10.1016/j.polymer.2013.04.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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35
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Efremov MY, Kiyanova AV, Last J, Soofi SS, Thode C, Nealey PF. Glass transition in thin supported polystyrene films probed by temperature-modulated ellipsometry in vacuum. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:021501. [PMID: 23005763 DOI: 10.1103/physreve.86.021501] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Indexed: 06/01/2023]
Abstract
Glass transition in thin (1-200 nm thick) spin-cast polystyrene films on silicon surfaces is probed by ellipsometry in a controlled vacuum environment. A temperature-modulated modification of the method is used alongside a traditional linear temperature scan. A clear glass transition is detected in films with thicknesses as low as 1-2 nm. The glass transition temperature (T(g)) shows no substantial dependence on thickness for coatings greater than 20 nm. Thinner films demonstrate moderate T(g) depression achieving 18 K for thicknesses 4-7 nm. Less than 4 nm thick samples are excluded from the T(g) comparison due to significant thickness nonuniformity (surface roughness). The transition in 10-20 nm thick films demonstrates excessive broadening. For some samples, the broadened transition is clearly resolved into two separate transitions. The thickness dependence of the glass transition can be well described by a simple 2-layer model. It is also shown that T(g) depression in 5 nm thick films is not sensitive to a wide range of experimental factors including molecular weight characteristics of the polymer, specifications of solvent used for spin casting, substrate composition, and pretreatment of the substrate surface.
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Affiliation(s)
- Mikhail Yu Efremov
- Department of Chemical and Biological Engineering and Center for Nanotechnology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
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37
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Kim K, Miyazaki K, Saito S. Slow dynamics, dynamic heterogeneities, and fragility of supercooled liquids confined in random media. J Phys Condens Matter 2011; 23:234123. [PMID: 21613691 DOI: 10.1088/0953-8984/23/23/234123] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Using molecular dynamics simulations, we study the slow dynamics of supercooled liquids confined in a random matrix of immobile obstacles. We study the dynamical crossover from glass-like to Lorentz-gas-like behavior in terms of the density correlation function, the mean square displacement, the nonlinear dynamic susceptibility, the non-gaussian parameter, and the fragility. We find the cooperative and spatially heterogeneous dynamics to be suppressed as the obstacle density increases, leading to a more Arrhenius-like behavior in the temperature dependence of the relaxation time. Our findings are qualitatively consistent with the results of recent experimental and numerical studies for various classes of spatially heterogeneous systems. We also investigate the dependence of the dynamics of mobile particles on the protocol used to generate the random matrix. A re-entrant transition from the arrested phase to the liquid phase as the mobile particle density increases is observed for a class of protocols. This re-entrance is explained in terms of the distribution of the volume of the voids that are available to the mobile particles.
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Affiliation(s)
- Kang Kim
- Institute for Molecular Science, Okazaki 444-8585, Japan.
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38
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Inoue R, Kawashima K, Matsui K, Kanaya T, Nishida K, Matsuba G, Hino M. Distributions of glass-transition temperature and thermal expansivity in multilayered polystyrene thin films studied by neutron reflectivity. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 83:021801. [PMID: 21405853 DOI: 10.1103/physreve.83.021801] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Indexed: 05/26/2023]
Abstract
We performed neutron reflectivity measurements on multilayered polymer thin films consisting of alternatively stacked deuterated polystyrene (d-PS) and hydrogenated polystyrene (h-PS) layers ∼200 Å thick as a function of temperature covering the glass-transition temperature T(g), and we found a wide distribution of T(g) as well as a distribution of the thermal expansivity α within the thin films, implying the dynamic heterogeneity of the thin films along the depth direction. The reported anomalous film thickness dependences of T(g) and α were reasonably understood in terms of the distributions, showing that the surface mobile layer and the bottom hard interfacial layer are, respectively, responsible for the depressions of T(g) and α with decreasing film thickness. The molecular mobility in each layer is also discussed in relation to the distribution of T(g), based on the results on mutual diffusion at the layer interface.
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Affiliation(s)
- Rintaro Inoue
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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