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Salvati Manni L, Wood K, Klapproth A, Warr GG. Inelastic neutron scattering and spectroscopy methods to characterize dynamics in colloidal and soft matter systems. Adv Colloid Interface Sci 2024; 326:103135. [PMID: 38520888 DOI: 10.1016/j.cis.2024.103135] [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: 01/10/2024] [Revised: 03/12/2024] [Accepted: 03/14/2024] [Indexed: 03/25/2024]
Abstract
Colloidal systems and soft materials are well suited to neutron scattering, and the community has readily adopted elastic scattering techniques to investigate their structure. Due to their unique properties, neutrons may also be used to characterize the dynamics of soft materials over a wide range of length and time scales in situ. Both static structures and an understanding of how molecules move about their equilibrium positions is essential if we are to deliver on the promise of rationally designing soft materials. In this review we introduce the basics of neutron spectroscopy and explore the ways in which inelastic neutron scattering can be used to study colloidal and soft materials. Illustrative examples are chosen that highlight the phenomena suitable for investigation using this suite of techniques.
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Affiliation(s)
- Livia Salvati Manni
- School of Chemistry, University of Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia; School of Chemistry, Monash University, Wellington Road, Clayton, VIC 3800, Australia; School of Environmental and Life Sciences, University of Newcastle, Callaghan 2308, NSW, Australia; Australian Synchrotron, ANSTO, 800 Blackburn Rd, Clayton, VIC 3168, Australia
| | - Kathleen Wood
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Alice Klapproth
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Gregory G Warr
- School of Chemistry, University of Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia.
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2
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Gagnon YJ, Burton JC, Roth CB. Development of broad modulus profile upon polymer-polymer interface formation between immiscible glassy-rubbery domains. Proc Natl Acad Sci U S A 2024; 121:e2312533120. [PMID: 38147561 PMCID: PMC10769838 DOI: 10.1073/pnas.2312533120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 11/01/2023] [Indexed: 12/28/2023] Open
Abstract
Interfaces of glassy materials such as thin films, blends, and composites create strong unidirectional gradients to the local heterogeneous dynamics that can be used to elucidate the length scales and mechanisms associated with the dynamic heterogeneity of glasses. We focus on bilayer films of two different polymers with very different glass transition temperatures ([Formula: see text]) where previous work has demonstrated a long-range (∼200 nm) profile in local [Formula: see text] is established between immiscible glassy and rubbery polymer domains when the polymer-polymer interface is formed to equilibrium. Here, we demonstrate that an equally long-ranged gradient in local modulus [Formula: see text] is established when the polymer-polymer interface ([Formula: see text]5 nm) is formed between domains of glassy polystyrene (PS) and rubbery poly(butadiene) (PB), consistent with previous reports of a broad [Formula: see text] profile in this system. A continuum physics model for the shear wave propagation caused by a quartz crystal microbalance across a PB/PS bilayer film is used to measure the viscoelastic properties of the bilayer during the evolution of the PB/PS interface showing the development of a broad gradient in local modulus [Formula: see text] spanning [Formula: see text]180 nm between the glassy and rubbery domains of PS and PB. We suggest these broad profiles in [Formula: see text] and [Formula: see text] arise from a coupling of the spectrum of vibrational modes across the polymer-polymer interface as a result of acoustic impedance matching of sound waves with [Formula: see text] nm during interface broadening that can then trigger density fluctuations in the neighboring domain.
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Affiliation(s)
| | | | - Connie B. Roth
- Department of Physics, Emory University, Atlanta, GA30322
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3
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Drużbicki K, Gaboardi M, Fernandez-Alonso F. Dynamics & Spectroscopy with Neutrons-Recent Developments & Emerging Opportunities. Polymers (Basel) 2021; 13:1440. [PMID: 33947108 PMCID: PMC8125526 DOI: 10.3390/polym13091440] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 04/27/2021] [Indexed: 12/19/2022] Open
Abstract
This work provides an up-to-date overview of recent developments in neutron spectroscopic techniques and associated computational tools to interrogate the structural properties and dynamical behavior of complex and disordered materials, with a focus on those of a soft and polymeric nature. These have and continue to pave the way for new scientific opportunities simply thought unthinkable not so long ago, and have particularly benefited from advances in high-resolution, broadband techniques spanning energy transfers from the meV to the eV. Topical areas include the identification and robust assignment of low-energy modes underpinning functionality in soft solids and supramolecular frameworks, or the quantification in the laboratory of hitherto unexplored nuclear quantum effects dictating thermodynamic properties. In addition to novel classes of materials, we also discuss recent discoveries around water and its phase diagram, which continue to surprise us. All throughout, emphasis is placed on linking these ongoing and exciting experimental and computational developments to specific scientific questions in the context of the discovery of new materials for sustainable technologies.
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Affiliation(s)
- Kacper Drużbicki
- Materials Physics Center, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastian, Spain;
- Polish Academy of Sciences, Center of Molecular and Macromolecular Studies, Sienkiewicza 112, 90-363 Lodz, Poland
| | - Mattia Gaboardi
- Elettra—Sincrotrone Trieste S.C.p.A., S.S. 14 km 163.5 in Area Science Park, 34149 Trieste, Italy;
| | - Felix Fernandez-Alonso
- Materials Physics Center, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastian, Spain;
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastian, Spain
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Spain
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4
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Monnier X, Colmenero J, Wolf M, Cangialosi D. Reaching the Ideal Glass in Polymer Spheres: Thermodynamics and Vibrational Density of States. PHYSICAL REVIEW LETTERS 2021; 126:118004. [PMID: 33798388 DOI: 10.1103/physrevlett.126.118004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 12/04/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
The existence of an ideal glass and the resolution to the Kauzmann paradox is a long-standing open question in materials science. To address this problem, we exploit the ability of glasses with large interfacial area to access low energy states. We submit aggregates of spheres of a polymeric glass former to aging well below their glass transition temperature, T_{g}; and characterize their thermodynamic state by calorimetry, and the vibrational density of state (VDOS) by inelastic neutron scattering (INS). We show that, when aged at appropriate temperatures, glassy spheres attain a thermodynamic state corresponding to an ideal glass in time scales of about one day. In this state, the boson peak, underlying the deviation from the Debye level of the VDOS, is essentially suppressed. Our results are discussed in the framework of the link between the macroscopic thermodynamic state of glasses and their vibrational properties.
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Affiliation(s)
- Xavier Monnier
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
| | - Juan Colmenero
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
- Departamento de Fisica de Materiales (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain
- Centro de Fisica de Materiales (CSIC-UPV/EHU) Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
| | - Marcel Wolf
- Heinz Maier-Leibnitz Zentrum (MLZ), Lichtenbergstrasse 1 85747, Garching, Germany
| | - Daniele Cangialosi
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
- Centro de Fisica de Materiales (CSIC-UPV/EHU) Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
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5
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Xu Q, Zhu N, Fang H, Wang X, Priestley RD, Zuo B. Decoupling Role of Film Thickness and Interfacial Effect on Polymer Thin Film Dynamics. ACS Macro Lett 2021; 10:1-8. [PMID: 35548993 DOI: 10.1021/acsmacrolett.0c00760] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The film thickness and substrate interface are the two most common parameters to tune the dynamics of supported thin films. Here, we investigated the glass transition temperature (Tg) and thermal expansion of thin poly(methyl methacrylate) (PMMA) films with various thicknesses and different interfacial effects. We showed that, although the Tg of the thin films can be modulated equivalently by the two factors, their ability to change the expansivity (β) is quite different; that is, β increases notably with a reduction in the thickness, while it is insensitive to perturbations at the interface. We attribute the deviation in modulating β by the thickness and the interfacial effect to the disparate abilities to change the free volume content in the film by a free surface and substrate interface. This leads to a situation where thin films with dissimilar thicknesses and interfacial properties can have the same Tg but very different β values, suggesting that Tg alone cannot unequivocally quantify thin film dynamics.
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Affiliation(s)
- Quanyin Xu
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Ningtao Zhu
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Huasong Fang
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Xinping Wang
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Rodney D. Priestley
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Biao Zuo
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
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6
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Xia W, Song J, Hsu DD, Keten S. Side-group size effects on interfaces and glass formation in supported polymer thin films. J Chem Phys 2018; 146:203311. [PMID: 28571359 DOI: 10.1063/1.4976702] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Recent studies on glass-forming polymers near interfaces have emphasized the importance of molecular features such as chain stiffness, side-groups, molecular packing, and associated changes in fragility as key factors that govern the magnitude of Tg changes with respect to the bulk in polymer thin films. However, how such molecular features are coupled with substrate and free surface effects on Tg in thin films remains to be fully understood. Here, we employ a chemically specific coarse-grained polymer model for methacrylates to investigate the role of side-group volume on glass formation in bulk polymers and supported thin films. Our results show that bulkier side-groups lead to higher bulk Tg and fragility and are associated with a pronounced free surface effect on overall Tg depression. By probing local Tg within the films, however, we find that the polymers with bulkier side-groups experience a reduced confinement-induced increase in local Tg near a strongly interacting substrate. Further analyses indicate that this is due to the packing frustration of chains near the substrate interface, which lowers the attractive interactions with the substrate and thus lessens the surface-induced reduction in segmental mobility. Our results reveal that the size of the polymer side-group may be a design element that controls the confinement effects induced by the free surface and substrates in supported polymer thin films. Our analyses provide new insights into the factors governing polymer dynamics in bulk and confined environments.
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Affiliation(s)
- Wenjie Xia
- Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
| | - Jake Song
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
| | - David D Hsu
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
| | - Sinan Keten
- Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
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7
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Mashita R, Inoue R, Tominaga T, Shibata K, Kishimoto H, Kanaya T. Quasielastic neutron scattering study of microscopic dynamics in polybutadiene reinforced with an unsaturated carboxylate. SOFT MATTER 2017; 13:7862-7869. [PMID: 29019368 DOI: 10.1039/c7sm01262d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We studied the dynamics of zinc diacrylate (ZDA) reinforced polybutadiene rubber (BR) (ZDA/BR) using the quasielastic neutron scattering technique to determine the effect of concentration of ZDA on polymer dynamics. First, we evaluated the temperature dependence of mean square displacements (〈u2〉) for ZDA/BR with different ZDA volume fractions. 〈u2〉 increased with temperature below 170 K, and we observed no significant ZDA volume fraction dependence. However, it increased more steeply above 170 K, and the value of 〈u2〉 was smaller for the samples with increasing ZDA fraction. To elucidate the origin of the decrease in 〈u2〉 with increasing ZDA content, dynamic scattering laws (S(Q,ω)) were analyzed. An increase in the elastic component, an increase in the mean relaxation time, and a broadening of distribution of relaxation time were observed with the increasing volume fraction of ZDA. In addition, the ZDA volume fraction dependence of the elastic component roughly corresponded to that of elastic modulus, indicating that the elastic component is related to its mechanical strength. Referring to the previously reported static structure of the present ZDA/BR system, a model for the heterogeneous BR dynamics was proposed. This model assumes the coexistence of immobile, mobile, and interfacial constrained mobile regions. It was found to be appropriate for the explanation of the observed dynamics. We proposed that a network-like structure of the BR having a high crosslinking density around ZDA aggregates is mainly responsible for the high elastic modulus of ZDA/BR.
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Affiliation(s)
- Ryo Mashita
- SUMITOMO Rubber Industries, LTD, 1-1, 2-chome, Tsutsui-cho, Chuo-ku, Kobe 651-0071, Japan
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8
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Vogt BD. Mechanical and viscoelastic properties of confined amorphous polymers. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/polb.24529] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Bryan D. Vogt
- Department of Polymer Engineering; University of Akron; Akron Ohio 44325
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9
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Zhang M, Askar S, Torkelson JM, Brinson LC. Stiffness Gradients in Glassy Polymer Model Nanocomposites: Comparisons of Quantitative Characterization by Fluorescence Spectroscopy and Atomic Force Microscopy. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00917] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Min Zhang
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Shadid Askar
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - John M. Torkelson
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - L. Catherine Brinson
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
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10
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Schönhals A, Zorn R, Frick B. Inelastic neutron spectroscopy as a tool to investigate nanoconfined polymer systems. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.06.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Stiffness of thin, supported polystyrene films: Free-surface, substrate, and confinement effects characterized via self-referencing fluorescence. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.07.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Madkour S, Yin H, Füllbrandt M, Schönhals A. Calorimetric evidence for a mobile surface layer in ultrathin polymeric films: poly(2-vinyl pyridine). SOFT MATTER 2015; 11:7942-7952. [PMID: 26324951 DOI: 10.1039/c5sm01558h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Specific heat spectroscopy was used to study the dynamic glass transition of ultrathin poly(2-vinyl pyridine) films (thicknesses: 405-10 nm). The amplitude and the phase angle of the differential voltage were obtained as a measure of the complex heat capacity. In a traditional data analysis, the dynamic glass transition temperature Tg is estimated from the phase angle. These data showed no thickness dependency on Tg down to 22 nm (error of the measurement of ±3 K). A derivative-based method was established, evidencing a decrease in Tg with decreasing thickness up to 7 K, which can be explained by a surface layer. For ultrathin films, data showed broadening at the lower temperature side of the spectra, supporting the existence of a surface layer. Finally, temperature dependence of the heat capacity in the glassy and liquid states changes with film thickness, which can be considered as a confinement effect.
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Affiliation(s)
- Sherif Madkour
- BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, D-12200 Berlin, Germany.
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14
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Residual stress relaxation and stiffness in spin-coated polymer films: Characterization by ellipsometry and fluorescence. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.08.036] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Chung PC, Green PF. The Elastic Mechanical Response of Nanoscale Thin Films of Miscible Polymer/Polymer Blends. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00392] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peter C. Chung
- Department
of Materials Science
and Engineering, Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Peter F. Green
- Department
of Materials Science
and Engineering, Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
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16
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Xia W, Hsu DD, Keten S. Molecular Weight Effects on the Glass Transition and Confinement Behavior of Polymer Thin Films. Macromol Rapid Commun 2015; 36:1422-7. [DOI: 10.1002/marc.201500194] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 04/23/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Wenjie Xia
- Department of Civil & Environmental Engineering and Department of Mechanical Engineering; Northwestern University; Evanston IL 60208 USA
| | - David D. Hsu
- Department of Civil & Environmental Engineering and Department of Mechanical Engineering; Northwestern University; Evanston IL 60208 USA
| | - Sinan Keten
- Department of Civil & Environmental Engineering and Department of Mechanical Engineering; Northwestern University; Evanston IL 60208 USA
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17
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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] [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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18
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Chung PC, Glynos E, Green PF. The elastic mechanical response of supported thin polymer films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:15200-15205. [PMID: 25470203 DOI: 10.1021/la503879v] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nanoindentation studies of the mechanical properties of sufficiently thin polymer films, supported by stiff substrates, indicate that the mechanical moduli are generally higher than those of the bulk. This enhancement of the effective modulus, in the thickness range of few hundred nanometers, is indicated to be associated with the propagation and impingement of the indentation tip induced stress field with the rigid underlying substrate; this is the so-called "substrate effect". This behavior has been rationalized completely in terms of the moduli and Poisson's ratios of the individual components, for the systems investigated thus far. Here we show that for thin supported polymer films, in general, information regarding the local chain stiffness and local vibrational constants of the polymers provides an appropriate rationalization of the overall mechanical response of polymers of differing chemical structures and polymer-substrate interactions. Our study should provide impetus for atomistic simulations that carefully account for the role of intermolecular interactions on the mechanical response of supported polymer thin films.
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Affiliation(s)
- Peter C Chung
- Department of Materials Science and Engineering, Biointerfaces Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
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19
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Matsuda Y, Hanamura R, Takemura Y, Sugita A, Tasaka S. Formation of a metastable phase of bisphenol-A polycarbonate induced by mechanical stress. J Appl Polym Sci 2012. [DOI: 10.1002/app.36747] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Affiliation(s)
- C. M. Roland
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington, D.C. 20375-5342
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21
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Inoue R, Kanaya T, Nishida K, Tsukushi I, Telling MTF, Gabrys BJ, Tyagi M, Soles C, Wu WL. Glass transition and molecular mobility in polymer thin films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:031802. [PMID: 19905138 DOI: 10.1103/physreve.80.031802] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Indexed: 05/28/2023]
Abstract
Extensive studies on polymer thin films to date have revealed their interesting but unusual properties such as film thickness dependence of glass transition temperature Tg and thermal expansivity. Recent studies have shown that the lower Tg is not always related to the higher mobility in polymer thin films, which contradicts our current understanding of the glass transition process. In this work, we report the results of inelastic neutron-scattering measurements on polystyrene thin films using two spectrometers with different energy resolutions as well as ellipsometry measurements. The results are interpreted in terms of cooperatively rearranging region and motional slowing down due to the surface effect that explain plausibly the anomalous relationship between the glass transition temperature Tg and the molecular mobility in thin films.
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Affiliation(s)
- R Inoue
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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22
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Ogawa H, Kanaya T, Nishida K, Matsuba G, Majewski JP, Watkins E. Time-resolved specular and off-specular neutron reflectivity measurements on deuterated polystyrene and poly(vinyl methyl ether) blend thin films during dewetting process. J Chem Phys 2009. [DOI: 10.1063/1.3224125] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Inoue R, Kanaya T, Nishida K, Tsukushi I, Shibata K. Molecular weight dependence of mean square displacement in ultrathin polymer films as studied by inelastic neutron scattering. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:032801. [PMID: 18517445 DOI: 10.1103/physreve.77.032801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Indexed: 05/26/2023]
Abstract
In previous papers, we found that the mean square displacement [u(2)] in polystyrene thin films decreased with film thickness and discussed two possible causes for the decrease. One is the hard interface layer between the polymer thin film and the substrate, and the other is the spatial confinement effect of polymer chains. In order to disclose the cause of the decrease of [u(2)] with film thickness, we studied the molecular weight M(w) dependence of [u(2)] in polystyrene thin films. We found that [u(2)] was independent of M(w) within experimental error, concluding that the interface effect is a main reason for the decrease of [u(2)] with film thickness.
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Affiliation(s)
- Rintaro Inoue
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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24
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Li Y, Pham JQ, Johnston KP, Green PF. Contact angle of water on polystyrene thin films: effects of CO(2) environment and film thickness. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:9785-93. [PMID: 17685637 DOI: 10.1021/la0636311] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We examine the contact angle of water droplets on polystyrene (PS) thin films of varying thicknesses supported by silicon wafers under both air and pressurized carbon dioxide (CO2) environments. At 23 degrees C, the contact angle is found to increase upon increasing CO2 pressure in the vapor regime and then levels off in the liquid CO2 regime. A macroscopic model based on Young's equation and the geometric-mean method for interfacial tensions, and long-range van der Waals interactions, correctly predicts the trends and the magnitude of the contact angle dependence on pressure, although deviations occur at high CO2 activities. The contact angle was also found to depend on film thickness, h, when h was comparable to or smaller than 50 nm. Specifically, the contact angle decreases with decreasing PS film thickness. This behavior could be accounted for with the use of a model that incorporates the effects of film thickness, CO2 pressure, and the long-range van der Waals potential.
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Affiliation(s)
- Yuan Li
- Graduate Program in Materials Science and Engineering, Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
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Inoue R, Kanaya T, Nishida K, Tsukushi I, Taylor J, Levett S, Gabrys BJ. Dynamic anisotropy and heterogeneity of polystyrene thin films as studied by inelastic neutron scattering. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2007; 24:55-60. [PMID: 17767375 DOI: 10.1140/epje/i2007-10210-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Accepted: 07/20/2007] [Indexed: 05/17/2023]
Abstract
We studied the dynamic anisotropy and heterogeniety of polystyrene thin films in glassy state with inelastic neutorn scattering. Adjusting the scattering vector to the directions parallel and perpendicular to the film surface, we observed the elastic scattering intensities as a function of temperature. It was found for the 200 A film that the elastic intesity decreased with increasing temperature more rapidly in the perpendicular direction than in the pararell direction, showing the higher mobility in the perpendicular direction. However, such dynamical anisotropy was not observed in the 1000 A film. The decrease in the mobility was observed with the film thickness in both the directions. These results were explained in terms of an interface hard layer. We also evelauated the dynamical heterogeniety from the non-Gaussian parameter A0, which increased with decreasing the film thickness, showing the increase in the dynamical heterogeneity. Assuming a simple bi-layer model consisting of the interface hard layer and the bulk-like layer, we analyzed the thickness dependence of the non-Gaussian parameter A0 and the mean square displacement (u2) to find that the hard layer has a thickness of approximately 130 A and a mean square displacement of approximately 0.018 A2 at 230 K.
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Affiliation(s)
- R Inoue
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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Besancon BM, Green PF. Dewetting dynamics in miscible polymer-polymer thin film mixtures. J Chem Phys 2007; 126:224903. [PMID: 17581079 DOI: 10.1063/1.2737043] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Thin polystyrene films supported by oxidized silicon (SiOx/Si) substrates may be unstable or metastable, depending on the film thickness, h, and can ultimately dewet the substrate when heated above their glass transition. In the metastable regime, holes nucleate throughout the film and subsequently grow due to capillary driving forces. Recent studies have shown that the addition of a second component, such as a copolymer or miscible polymer, can suppress the dewetting process and stabilize the film. We examined the hole growth dynamics and the hole morphology in thin film mixtures composed of polystyrene and tetramethyl bisphenol-A polycarbonate (TMPC) supported by SiOx/Si substrates. The hole growth velocity decreased with increasing TMPC content beyond that expected from changes in the bulk viscosity. The authors show that the suppression of the dewetting velocity is primarily due to reductions in the capillary driving force for dewetting and to increased friction at the substrate-polymer interface. The viscosity, as determined from the hole growth dynamics, decreases with decreasing film thickness, and is connected to a depression of the glass transition of the film.
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Affiliation(s)
- Brian M Besancon
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
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Besancon BM, Soles CL, Green PF. Glass transition of miscible binary polymer-polymer thin films. PHYSICAL REVIEW LETTERS 2006; 97:057801. [PMID: 17026142 DOI: 10.1103/physrevlett.97.057801] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Indexed: 05/12/2023]
Abstract
The average glass transition temperatures, Tg, of thin homopolymer films exhibit a thickness dependence, Tg(h), associated with a confinement effect and with polymer-segment-interface interactions. The Tg's of completely miscible thin film blends of tetramethyl bisphenol-A polycarbonate (TMPC) and deuterated polystyrene (dPS), supported by SiO(x)/Si, decrease with decreasing h for PS weight fractions phi >0.1. This dependence is similar to that of PS and opposite to that of TMPC thin films. Based on an assessment of Tg(h, phi), we suggest that the Tg(h, phi) of miscible blends should be rationalized, additionally, in terms of the notion of a self-concentration and associated heterogeneous component dynamics.
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Affiliation(s)
- Brian M Besancon
- Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, USA
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Inoue R, Kanaya T, Nishida K, Tsukushi I, Shibata K. Low-energy excitations and the fast process of polystyrene thin supported films studied by inelastic and quasielastic neutron scattering. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:021801. [PMID: 17025460 DOI: 10.1103/physreve.74.021801] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Indexed: 05/12/2023]
Abstract
We studied the low-energy excitations in the meV region as well as the picosecond fast process in polystyrene thin supported films using inelastic and quasielastic neutron scattering in a temperature range from 11 to 430 K , covering the bulk glass transition temperature Tg. It was found that the mean square displacement u2 decreased with the film thickness below and above the glass transition temperature Tg, suggesting that the hardening occurs with decreasing the film thickness. Corresponding to the decrease in u2, it was also found that the density of phonon states G(omega) decreased with film thickness. This decrease occurs mainly in the Debye mode while the contribution of the boson peak mode also decreases with the film thickness without changing the boson peak energy. As for the fast process, which appeared above at about 150 K as a quasielastic scattering, the fraction A(fast)(Q) decreased with the film thickness in a similar manner with the boson peak without changing the relaxation rate, suggesting a common origin for the boson peak and the fast process. These observations showing the hardening were well explained by assuming a hard dense layer at the interface, where the numbers of the boson peak mode as well as the fast process are less than the bulk state.
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Affiliation(s)
- Rintaro Inoue
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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Ciliberti S, De Los Rios P, Piazza F. Glasslike structure of globular proteins and the boson peak. PHYSICAL REVIEW LETTERS 2006; 96:198103. [PMID: 16803144 DOI: 10.1103/physrevlett.96.198103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Indexed: 05/10/2023]
Abstract
Vibrational spectra of proteins and topologically disordered solids display a common anomaly at low frequencies, known as boson peak. We show that such feature in globular proteins can be deciphered in terms of an energy landscape picture, as it is for glassy systems. Exploiting the tools of Euclidean random matrix theory, we clarify the physical origin of such anomaly in terms of a mechanical instability of the system. As a natural explanation, we argue that such instability is relevant for proteins in order for their molecular functions to be optimally rooted in their structures.
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Affiliation(s)
- Stefano Ciliberti
- Laboratoire de Physique Théorique et Modèles Statistiques, Université de Paris-Sud, Orsay, France
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Ashley KM, Raghavan D, Douglas JF, Karim A. Wetting-dewetting transition line in thin polymer films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:9518-23. [PMID: 16207030 DOI: 10.1021/la050482y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Thin polymeric films are increasingly being utilized in diverse technological applications, and it is crucial to have a reliable method to characterize the stability of these films against dewetting. The parameter space that influences the dewetting of thin polymer films is wide (molecular mass, temperature, film thickness, substrate interaction) and a combinatorial method of investigation is suitable. We thus construct a combinatorial library of observations for polystyrene (PS) films cast on substrates having orthogonal temperature and surface energy gradients and perform a series of measurements for a range of molecular masses (1800 g/mol < M < 35 000 g/mol) and film thicknesses h (30 nm < h < 40 nm) to explore these primary parameter axes. We were able to obtain a near-universal scaling curve describing a wetting-dewetting transition line for polystyrene films of fixed thickness by introducing reduced temperature and surface energy variables dependent on M. Our observations also indicate that the apparent polymer surface tension gamma(p) becomes appreciably modified in thin polymer films from its bulk counterpart for films thinner than about 100-200 nm, so that bulk gamma(p) measurements cannot be used to estimate the stability of ultrathin films. Both of these observations are potentially fundamental for the control of thin film stability in applications where film dewetting can compromise film function.
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Affiliation(s)
- K M Ashley
- Polymer Program, Department of Chemistry, Howard University, Washington, DC 20059, USA
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