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Lee TI, Kim JH, Kim DJ, Kim TS. Evaluating Free Thermal Expansion and Glass Transition of Ultrathin Polymer Films on Heated Liquid. ACS APPLIED MATERIALS & INTERFACES 2024; 16:30336-30343. [PMID: 38781291 DOI: 10.1021/acsami.4c02279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Thermomechanical properties of ultrathin films are crucial for fabrication and use of reliable thin electronic devices. Due to the lack of precise measurement techniques, the thermal deformation behavior of ultrathin films has not yet been clarified. Here, we propose a film on heated liquid (FOHL) method to simultaneously measure the coefficient of thermal expansion (CTE) and glass transition temperature (Tg) of multiple ultrathin polymer films. Free thermal expansion of thin films without substrate interaction can be guaranteed when the thin films are afloat on a liquid surface. To investigate the thermal behavior in a wide temperature range, glycerol is adopted as a thermally stable heating platform owing to its high boiling point of 290 °C. The thin films are transferred onto the glycerol surface from the water surface using the hygroscopic properties of glycerol. Highly accurate and high-throughput thermal strain measurement is achieved using three-dimensional digital image correlation (3D-DIC). The thermomechanical properties of ultrathin polystyrene thin films of various thicknesses (25-400 nm) are precisely characterized utilizing the FOHL and 3D-DIC method.
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Affiliation(s)
- Tae-Ik Lee
- Advanced Packaging and Integration Center, Joining R&D Group, KITECH, 156 Gaetbeol-ro, Yeonsu-gu, Incheon 21999, Republic of Korea
| | - Ji Hun Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Dong Jun Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Taek-Soo Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
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2
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Wang G, Shi G, Yang A, Wang B, Shen C, Chen J, Reiter G, Zhang B. Determining the maximum melting temperature of polymer crystals from a change in morphology of dewetting rims. POLYMER 2023. [DOI: 10.1016/j.polymer.2023.125874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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3
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Mulama AA, Roumpos K, Pradipkanti L, Oduor AO, Reiter G. Rheological Properties of Blends of Isotactic Polystyrene–Isotactic Poly( para-methylstyrene) Films Derived from a Comparative Dewetting Study. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Austine A. Mulama
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
- Department of Physics and Materials Science, School of Physical and Biological Sciences, Maseno University, 333, 40105 Maseno, Kenya
| | - Konstantinos Roumpos
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
| | - L. Pradipkanti
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
| | - Andrew O. Oduor
- Department of Physics and Materials Science, School of Physical and Biological Sciences, Maseno University, 333, 40105 Maseno, Kenya
| | - Günter Reiter
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
- Freiburg Center for Interactive Materials and Bio-inspired Technologies (FIT), Albert-Ludwigs-Universität, Freiburg 79110, Germany
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Mulama AA, Chandran S, Roumpos K, Oduor AO, Reiter G. Dewetting Rheology for Determining Viscoelastic Properties of Nonequilibrated Thin Polymer Films. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01384] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Austine A. Mulama
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
- Department of Physics and Materials Science, School of Biological and Physical Sciences, Maseno University, PO Box 333-40105, Maseno, Kenya
| | - Sivasurender Chandran
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
| | - Konstantinos Roumpos
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
| | - Andrew O. Oduor
- Department of Physics and Materials Science, School of Biological and Physical Sciences, Maseno University, PO Box 333-40105, Maseno, Kenya
| | - Günter Reiter
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
- Freiburg Center for Interactive Materials and Bio-inspired Technologies (FIT), Albert-Ludwigs-Universität, Freiburg 79110, Germany
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Peschka D, Haefner S, Marquant L, Jacobs K, Münch A, Wagner B. Signatures of slip in dewetting polymer films. Proc Natl Acad Sci U S A 2019; 116:9275-9284. [PMID: 31004049 PMCID: PMC6510987 DOI: 10.1073/pnas.1820487116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Thin polymer films on hydrophobic substrates are susceptible to rupture and hole formation. This, in turn, initiates a complex dewetting process, which ultimately leads to characteristic droplet patterns. Experimental and theoretical studies suggest that the type of droplet pattern depends on the specific interfacial condition between the polymer and the substrate. Predicting the morphological evolution over long timescales and on the different length scales involved is a major computational challenge. In this study, a highly adaptive numerical scheme is presented, which allows for following the dewetting process deep into the nonlinear regime of the model equations and captures the complex dynamics, including the shedding of droplets. In addition, our numerical results predict the previously unknown shedding of satellite droplets during the destabilization of liquid ridges that form during the late stages of the dewetting process. While the formation of satellite droplets is well known in the context of elongating fluid filaments and jets, we show here that, for dewetting liquid ridges, this property can be dramatically altered by the interfacial condition between polymer and substrate, namely slip. This work shows how dissipative processes can be used to systematically tune the formation of patterns.
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Affiliation(s)
- Dirk Peschka
- Weierstrass Institute for Applied Analysis and Stochastics, 10117 Berlin, Germany;
| | - Sabrina Haefner
- Experimental Physics and Center for Biophysics, Saarland University, 66041 Saarbrücken, Germany
| | - Ludovic Marquant
- Experimental Physics and Center for Biophysics, Saarland University, 66041 Saarbrücken, Germany
| | - Karin Jacobs
- Experimental Physics and Center for Biophysics, Saarland University, 66041 Saarbrücken, Germany
| | - Andreas Münch
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
| | - Barbara Wagner
- Weierstrass Institute for Applied Analysis and Stochastics, 10117 Berlin, Germany
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7
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Telford AM, Thickett SC, Neto C. Functional patterned coatings by thin polymer film dewetting. J Colloid Interface Sci 2017; 507:453-469. [DOI: 10.1016/j.jcis.2017.07.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 06/28/2017] [Accepted: 07/02/2017] [Indexed: 01/20/2023]
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8
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Napolitano S, Glynos E, Tito NB. Glass transition of polymers in bulk, confined geometries, and near interfaces. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:036602. [PMID: 28134134 DOI: 10.1088/1361-6633/aa5284] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
When cooled or pressurized, polymer melts exhibit a tremendous reduction in molecular mobility. If the process is performed at a constant rate, the structural relaxation time of the liquid eventually exceeds the time allowed for equilibration. This brings the system out of equilibrium, and the liquid is operationally defined as a glass-a solid lacking long-range order. Despite almost 100 years of research on the (liquid/)glass transition, it is not yet clear which molecular mechanisms are responsible for the unique slow-down in molecular dynamics. In this review, we first introduce the reader to experimental methodologies, theories, and simulations of glassy polymer dynamics and vitrification. We then analyse the impact of connectivity, structure, and chain environment on molecular motion at the length scale of a few monomers, as well as how macromolecular architecture affects the glass transition of non-linear polymers. We then discuss a revised picture of nanoconfinement, going beyond a simple picture based on interfacial interactions and surface/volume ratio. Analysis of a large body of experimental evidence, results from molecular simulations, and predictions from theory supports, instead, a more complex framework where other parameters are relevant. We focus discussion specifically on local order, free volume, irreversible chain adsorption, the Debye-Waller factor of confined and confining media, chain rigidity, and the absolute value of the vitrification temperature. We end by highlighting the molecular origin of distributions in relaxation times and glass transition temperatures which exceed, by far, the size of a chain. Fast relaxation modes, almost universally present at the free surface between polymer and air, are also remarked upon. These modes relax at rates far larger than those characteristic of glassy dynamics in bulk. We speculate on how these may be a signature of unique relaxation processes occurring in confined or heterogeneous polymeric systems.
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Affiliation(s)
- Simone Napolitano
- Laboratory of Polymer and Soft Matter Dynamics, Faculté des Sciences, Université Libre de Bruxelles (ULB), Boulevard du Triomphe, 1050 Brussels, Belgium
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9
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Chandran S, Reiter G. Transient Cooperative Processes in Dewetting Polymer Melts. PHYSICAL REVIEW LETTERS 2016; 116:088301. [PMID: 26967445 DOI: 10.1103/physrevlett.116.088301] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Indexed: 06/05/2023]
Abstract
We compare the high velocity dewetting behavior, at elevated temperatures, of atactic polystyrene (aPS) and isotactic polystyrene (iPS) films, with the zero shear bulk viscosity (η_{bulk}) of aPS being approximately ten times larger than iPS. As expected, for aPS the apparent viscosity of the films (η_{f}) derived from high-shear dewetting is less than η_{bulk}, displaying a shear thinning behavior. Surprisingly, for iPS films, η_{f} is always larger than η_{bulk}, even at about 50 °C above the melting point, with η_{f}/η_{bulk} following an Arrhenius behavior. The corresponding activation energy of ∼160±10 kJ/mol for iPS films suggests a cooperative motion of segments which are aligned and agglomerated by fast dewetting.
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Affiliation(s)
| | - Günter Reiter
- Institute of Physics, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany
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10
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Mukherjee R, Sharma A. Instability, self-organization and pattern formation in thin soft films. SOFT MATTER 2015; 11:8717-8740. [PMID: 26412507 DOI: 10.1039/c5sm01724f] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The free surface of a thin soft polymer film is often found to become unstable and self-organizes into various meso-scale structures. In this article we classify the instability of a thin polymer film into three broad categories, which are: category 1: instability of an ultra-thin (<100 nm) viscous film engendered by amplification of thermally excited surface capillary waves due to interfacial dispersive van der Waals forces; category 2: instability arising from the attractive inter-surface interactions between the free surface of a soft film exhibiting room temperature elasticity and another rigid surface in its contact proximity; and category 3: instability caused by an externally applied field such as an electric field or a thermal gradient, observed in both viscous and elastic films. We review the salient features of each instability class and highlight how characteristic length scales, feature morphologies, evolution pathways, etc. depend on initial properties such as film thickness, visco-elasticity (rheology), residual stress, and film preparation conditions. We emphasize various possible strategies for aligning and ordering of the otherwise isotropic structures by combining the essential concepts of bottom-up and top-down approaches. A perspective, including a possible future direction of research, novelty and limitations of the methods, particularly in comparison to the existing patterning techniques, is also presented for each setting.
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Affiliation(s)
- Rabibrata Mukherjee
- Instability and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, 721 302, India.
| | - Ashutosh Sharma
- Department of Chemical Engineering and Nano-science Center, Indian Institute of Technology, Kanpur, 208016, India.
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11
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Bäumchen O, Marquant L, Blossey R, Münch A, Wagner B, Jacobs K. Influence of slip on the Rayleigh-Plateau rim instability in dewetting viscous films. PHYSICAL REVIEW LETTERS 2014; 113:014501. [PMID: 25032928 DOI: 10.1103/physrevlett.113.014501] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Indexed: 06/03/2023]
Abstract
A dewetting viscous film develops a characteristic fluid rim at its receding edge due to mass conservation. In the course of the dewetting process, the rim becomes unstable via an instability of Rayleigh-Plateau type. An important difference exists between this classic instability of a liquid column and the rim instability in a thin film as the growth of the rim is continuously fueled by the receding film. We explain how the development and macroscopic morphology of the rim instability are controlled by the slip of the film on the substrate. A single thin-film model captures quantitatively the characteristics of the complete evolution of the rim observed in the experiments.
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Affiliation(s)
- Oliver Bäumchen
- Saarland University, Department of Experimental Physics, Campus, D-66123 Saarbrücken, Germany
| | - Ludovic Marquant
- Saarland University, Department of Experimental Physics, Campus, D-66123 Saarbrücken, Germany
| | - Ralf Blossey
- Interdisciplinary Research Institute (IRI), CNRS USR 3078, 59658 Villeneuve d'Ascq, France
| | - Andreas Münch
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
| | - Barbara Wagner
- Technical University of Berlin, Institute for Mathematics, D-10623 Berlin, Germany
| | - Karin Jacobs
- Saarland University, Department of Experimental Physics, Campus, D-66123 Saarbrücken, Germany
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12
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Li X, He Y, Wang Y, Dong J, Li H. Dewetting properties of metallic liquid film on nanopillared graphene. Sci Rep 2014; 4:3938. [PMID: 24487279 PMCID: PMC3909898 DOI: 10.1038/srep03938] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 01/15/2014] [Indexed: 01/27/2023] Open
Abstract
In this work, we report simulation evidence that the graphene surface decorated by carbon nanotube pillars shows strong dewettability, which can give it great advantages in dewetting and detaching metallic nanodroplets on the surfaces. Molecular dynamics (MD) simulations show that the ultrathin liquid film first contracts then detaches from the graphene on a time scale of several nanoseconds, as a result of the inertial effect. The detaching velocity is in the order of 10 m/s for the droplet with radii smaller than 50 nm. Moreover, the contracting and detaching behaviors of the liquid film can be effectively controlled by tuning the geometric parameters of the liquid film or pillar. In addition, the temperature effects on the dewetting and detaching of the metallic liquid film are also discussed. Our results show that one can exploit and effectively control the dewetting properties of metallic nanodroplets by decorating the surfaces with nanotube pillars.
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Affiliation(s)
- Xiongying Li
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, P. R. China
| | - Yezeng He
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, P. R. China
| | - Yong Wang
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, P. R. China
| | - Jichen Dong
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, P. R. China
| | - Hui Li
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, P. R. China
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13
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Xia T, Ogawa H, Inoue R, Nishida K, Yamada NL, Li G, Kanaya T. Dewetting Process of Deuterated Polystyrene and Poly(vinyl methyl ether) Blend Thin Films via Phase Separation. Macromolecules 2013. [DOI: 10.1021/ma400506f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Tian Xia
- College of Polymer Science and
Engineering, Sichuan University, Chengdu
610065, China
- Institute
for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
| | - Hiroki Ogawa
- Japan Synchrotron Radiation Research Institute, Sayo-gun, Hyogo-ken 679-5198,
Japan
| | - Rintaro Inoue
- Institute
for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
| | - Koji Nishida
- Institute
for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
| | - Norifumi L. Yamada
- High Energy Accelerator Research Organization, Tokai, Ibaraki-ken 319-1106,
Japan
| | - Guangxian Li
- College of Polymer Science and
Engineering, Sichuan University, Chengdu
610065, China
| | - Toshiji Kanaya
- Institute
for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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14
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Zhang P, Wang Z, Huang H, He T. Direct Observation of the Relief Structure Formation in the Nearly Symmetric Poly(styrene)-block-poly(ε-caprolactone) Diblock Copolymer Thin Film. Macromolecules 2012. [DOI: 10.1021/ma301531a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Peng Zhang
- State Key Laboratory of Polymer
Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate
School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022, People’s Republic
of China
| | - Zongbao Wang
- Ningbo Key Laboratory
of Polymer
Materials, Ningbo Institute of Material Technology and Engineering, Ningbo 315201, People’s Republic
of China
| | - Haiying Huang
- State Key Laboratory of Polymer
Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate
School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022, People’s Republic
of China
| | - Tianbai He
- State Key Laboratory of Polymer
Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate
School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022, People’s Republic
of China
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15
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Ma M, Chen F, Wang K, Zhang Q, Deng H, Li Z, Fu Q. Anisotropic Dewetting Holes with Instability Fronts in Ultrathin Films of Polystyrene/Poly(ε-caprolactone) Blend. Macromolecules 2012. [DOI: 10.1021/ma3000779] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Meng Ma
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Feng Chen
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Ke Wang
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Qin Zhang
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Hua Deng
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Zhongming Li
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Qiang Fu
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
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16
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Probing Properties of Polymers in Thin Films Via Dewetting. GLASS TRANSITION, DYNAMICS AND HETEROGENEITY OF POLYMER THIN FILMS 2012. [DOI: 10.1007/12_2012_174] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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17
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Xu L, Sharma A, Joo SW. Growth of Noncircular and Faceted Holes in Liquid–Liquid Dewetting of Thin Polymer Bilayers. Macromolecules 2011. [DOI: 10.1021/ma201538p] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lin Xu
- School of Mechanical Engineering, Yeungnam University, Gyongsan 712-749, South Korea
| | - Ashutosh Sharma
- School of Mechanical Engineering, Yeungnam University, Gyongsan 712-749, South Korea
- Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
| | - Sang W. Joo
- School of Mechanical Engineering, Yeungnam University, Gyongsan 712-749, South Korea
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18
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Patra A, Bandyopadhyay D, Tomar G, Sharma A, Biswas G. Instability and dewetting of ultrathin solid viscoelastic films on homogeneous and heterogeneous substrates. J Chem Phys 2011; 134:064705. [DOI: 10.1063/1.3554748] [Citation(s) in RCA: 13] [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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19
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Kearns KL, Whitaker KR, Ediger MD, Huth H, Schick C. Observation of low heat capacities for vapor-deposited glasses of indomethacin as determined by AC nanocalorimetry. J Chem Phys 2010; 133:014702. [DOI: 10.1063/1.3442416] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Bäumchen O, Jacobs K. Slip effects in polymer thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:033102. [PMID: 21386275 DOI: 10.1088/0953-8984/22/3/033102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Probing the fluid dynamics of thin films is an excellent tool for studying the solid/liquid boundary condition. There is no need for external stimulation or pumping of the liquid, due to the fact that the dewetting process, an internal mechanism, acts as a driving force for liquid flow. Viscous dissipation, within the liquid, and slippage balance interfacial forces. Thus, friction at the solid/liquid interface plays a key role towards the flow dynamics of the liquid. Probing the temporal and spatial evolution of growing holes or retracting straight fronts gives, in combination with theoretical models, information on the liquid flow field and, especially, the boundary condition at the interface. We review the basic models and experimental results obtained during the last several years with exclusive regard to polymers as ideal model liquids for fluid flow. Moreover, concepts that aim to explain slippage on the molecular scale are summarized and discussed.
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Affiliation(s)
- O Bäumchen
- Department of Experimental Physics, Saarland University, D-66041 Saarbrücken, Germany
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21
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Bäumchen O, Fetzer R, Jacobs K. Reduced interfacial entanglement density affects the boundary conditions of polymer flow. PHYSICAL REVIEW LETTERS 2009; 103:247801. [PMID: 20366229 DOI: 10.1103/physrevlett.103.247801] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Indexed: 05/29/2023]
Abstract
Hydrodynamic boundary conditions play a crucial role in the flow dynamics of thin films and can be probed by the analysis of liquid front profiles. For long-chained polymer films it was reported that a deviation from a symmetric profile is a result of viscoelastic effects. In this Letter, however, evidence is given that merely a slip-boundary condition at the solid-liquid interface can lead to an asymmetric profile. Variation of molecular weight shows that slippage is directly linked to chain entanglements. We find a reduced entanglement density at the solid-liquid interface (factors 3 to 4), which stresses the importance of considering nonbulk polymer properties in the vicinity of an interface.
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Affiliation(s)
- O Bäumchen
- Department of Experimental Physics, Saarland University, D-66041 Saarbrücken, Germany
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22
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Ziebert F, Raphaël E. Dewetting dynamics of stressed viscoelastic thin polymer films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:031605. [PMID: 19391952 DOI: 10.1103/physreve.79.031605] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Indexed: 05/27/2023]
Abstract
Ultrathin polymer films that are produced, e.g., by spin coating are believed to be stressed since polymers are "frozen in" into out-of-equilibrium configurations during this process. In the framework of a viscoelastic thin-film model, we study the effects of lateral residual stresses on the dewetting dynamics of the film. The temporal evolution of the height profiles and the velocity profiles inside the film as well as the dissipation mechanisms are investigated in detail. Both the shape of the profiles and the importance of frictional dissipation vs viscous dissipation inside the film are found to change in the course of dewetting. The interplay of the nonstationary profiles, the relaxing initial stress, and the changes in the dominance of the two dissipation mechanisms caused by nonlinear friction with the substrate is responsible for the rich behavior of the system. In particular, our analysis sheds a different light on the occurrence of the unexpected maximum in the rim width obtained recently in experiments on polystyrene-polydimethylsiloxane systems.
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Affiliation(s)
- Falko Ziebert
- Laboratoire de Physico-Chimie Théorique-UMR CNRS Gulliver 7083, ESPCI, 10 rue Vauquelin, F-75231 Paris, France
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Burtovyy R, Luzinov I. Reversibility of pH-induced dewetting of poly(vinyl pyridine) thin films on silicon oxide substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:5903-5910. [PMID: 18465886 DOI: 10.1021/la703545t] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Thin PVP films deposited on a silicon oxide surface have been found to form a dewetting pattern when treated with basic solutions (pH > or = 10). We studied the dependence of pattern morphology on the polymer's molecular weight and thickness of the polymer layer, and observed the formation of three distinctive structures. The structure formed by large drops of polymer is characteristic of a polymer with low molecular weight and the thinnest polymer layer, whereas other samples form holes or a weblike pattern upon dewetting. These experiments have demonstrated for the first time the reversibility of the dewetting process in a liquid environment. The polymer layer has revealed reversible behavior toward flat film when exposed to a pH 4 buffer solution. More complex structures can be obtained by consecutive treatments with acidic (pH 4) and basic (pH 10) solutions. We used atomic force microscopy (AFM) to study both the morphology and elastic properties of polymers in media with different acidity, in order to determine the mechanism behind the dewetting process.
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Affiliation(s)
- Ruslan Burtovyy
- School of Materials Science and Engineering, 161 Sirrine Hall, Clemson University, Clemson, SC 29634, USA
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24
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Affiliation(s)
- S. Joon Kwon
- Nano Science and Technology Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, Korea
| | - Jae-Gwan Park
- Nano Science and Technology Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, Korea
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25
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Fetzer R, Jacobs K. Slippage of Newtonian liquids: influence on the dynamics of dewetting thin films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:11617-11622. [PMID: 17918979 DOI: 10.1021/la701746r] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Slippage of Newtonian liquids in the presence of a solid substrate is a newly found phenomenon, the origin of which is still under debate. In this article, we present a new analysis method to extract the slip length. Enhancing the slip of liquids is an important issue for microfluidic devices that demand for high throughput at low pumping power. We study the velocity of short-chained liquid polystyrene (PS) films dewetting from nonwettable solid substrates. We show how the dynamics of dewetting is influenced by slippage, and we compare the results of two types of substrates that give rise to different slip lengths. As substrates, Si wafers that have been coated with octadecyltrichlorosilane (OTS) or dodecyltrichlorosilane (DTS) were used. Our results demonstrate that the dewetting velocity for PS films on DTS is significantly larger than on OTS and that this difference originates from the different slip lengths of the liquid on top of the two surfaces. For PS films of thickness between 130 and 230 nm, we find slip lengths between 400 nm and 6 microm, depending on substrate and temperature.
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Affiliation(s)
- R Fetzer
- Department of Experimental Physics, Saarland University, D-66041 Saarbrücken, Germany
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26
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Xu L, Shi T, An L. Nonsolvent-induced dewetting of thin polymer films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:9282-6. [PMID: 17676878 DOI: 10.1021/la700805f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The process of nonsolvent-induced dewetting of thin polystyrene (PS) films on hydrophilic surfaces at room temperature has been studied by using water as a nonsolvent. It is observed that the process of nonsolvent-induced dewetting is greatly different from other previous dewetting processes. The PS film is found in nonviscous state in our study. A mechanism of nonsolvent-induced dewetting is deduced in an order of penetration, replacement, and coalescent, and it is different from other previous dewetting mechanisms. The results of experiments are analyzed from thermodynamics and dynamics to support the hypothetical mechanism.
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Affiliation(s)
- Lin Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, PR China
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27
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Kosaka PM, Kawano Y, Petri DFS. Dewetting and surface properties of ultrathin films of cellulose esters. J Colloid Interface Sci 2007; 316:671-7. [PMID: 17707857 DOI: 10.1016/j.jcis.2007.07.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 07/16/2007] [Accepted: 07/17/2007] [Indexed: 11/26/2022]
Abstract
Surface properties of ultrathin films of cellulose esters deposited onto silicon wafers have been investigated by means of contact angle measurements and atomic force microscopy (AFM). Cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB) films adsorbed or spin-coated onto Si wafers were annealed up to one week. Film stability was monitored by AFM. Dewetting has been observed for CA and CAP. Only CAB films with lower degree of esterification presented dewetting, CAB films with high degree of butyrate were stable even after one week annealing. Surface energy of CA, CAP, and CAB was indirectly determined by contact angle measurements using drops of water, formamide and diiodomethane. The surface energy decreased as the size of alkyl ester group or the degree of esterification increased because van der Waals interactions became weaker. Effective Hamaker constant A(eff) was calculated for CA, CAP, and CAB onto Si wafers in air. Negative values of A(eff) were found for CA, CAP, and lower butyrate content CAB, which are related to instability and agree with dewetting phenomena observed by AFM. In contrast, a positive A(eff) was determined for higher butyrate content CAB, corroborating with experimental observations.
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Affiliation(s)
- P M Kosaka
- Universidade de São Paulo, Instituto de Quimica, Av. Prof. Lineu Prestes 748, 05508-900 São Paulo, Brazil
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28
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Damman P, Gabriele S, Coppée S, Desprez S, Villers D, Vilmin T, Raphaël E, Hamieh M, Akhrass SA, Reiter G. Relaxation of residual stress and reentanglement of polymers in spin-coated films. PHYSICAL REVIEW LETTERS 2007; 99:036101. [PMID: 17678296 DOI: 10.1103/physrevlett.99.036101] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 03/22/2007] [Indexed: 05/16/2023]
Abstract
Performing detailed studies of viscoelastic dewetting of thin polystyrene films on solid substrates, we demonstrate the existence of residual stress due to strongly out of equilibrium chain conformations and a reduced entanglement density resulting from film preparation by spin coating. The ratio of stress over elastic modulus was found to increase strongly with decreasing film thickness and increasing chain length. Full equilibration of chain conformations required long times comparable to bulk reptation times. However, for chains longer than about 3000 monomers, the residual stress relaxed faster, at a rate independent of chain length.
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Affiliation(s)
- Pascal Damman
- Laboratoire de Physicochimie des Polymères, Centre d'Innovation et de Recherche en Matériaux Polymères, Université de Mons Hainaut, 20, Place du Parc, B-7000 Mons, Belgium.
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29
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Julthongpiput D, Zhang W, Douglas JF, Karim A, Fasolka MJ. Pattern-directed to isotropic dewetting transition in polymer films on micropatterned surfaces with differential surface energy contrast. SOFT MATTER 2007; 3:613-618. [PMID: 32900025 DOI: 10.1039/b608630f] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Surface chemical patterns can both cause and direct dewetting in overlying thin polymer films. In this paper we focus on a key factor in this phenomenon, the magnitude of the surface energy difference between surface pattern domains (Δ). To probe the influence of Δ on film dewetting, we utilize novel combinatorial test patterns exhibiting a gradient in Δ. Specifically, our test patterns consist of a series of micron-scale striped regions that continuously change in their surface energy () relative to background striped regions having a fixed and calibrated . Using polystyrene (PS) films as a demonstration case, we employ these test patterns to quantify the morphology and kinetics of dewetting as Δ diminishes. Our study indicates a transition from pattern-directed to isotropic PS dewetting at critical Δ values. For Δ > 14 mJ m, ordered droplet arrays are formed, while for Δ < 7 mJ m, the dewetting is isotropic. A competition between these limiting behaviors is found for a "crossover regime", 7 mJ m < Δ < 14 mJ m. These combinatorial test patterns provide a powerful approach for investigating the large number of parameters that govern the stability of ultrathin polymer films, and the physical factors that influence the dewetted film morphology.
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Affiliation(s)
| | - Wenhua Zhang
- Polymers Division, NIST, Gaithersburg MD 20899, USA.
| | | | - Alamgir Karim
- Polymers Division, NIST, Gaithersburg MD 20899, USA.
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30
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Bertrand E, Blake TD, Ledauphin V, Ogonowski G, Coninck JD, Fornasiero D, Ralston J. Dynamics of dewetting at the nanoscale using molecular dynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:3774-85. [PMID: 17328565 DOI: 10.1021/la062920m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Large-scale molecular dynamics simulations are used to model the dewetting of solid surfaces by partially wetting thin liquid films. Two levels of solid-liquid interaction are considered that give rise to large equilibrium contact angles. The initial length and thickness of the films are varied over a wide range at the nanoscale. Spontaneous dewetting is initiated by removing a band of molecules either from each end of the film or from its center. As observed experimentally and in previous simulations, the films recede at an initially constant speed, creating a growing rim of liquid with a constant receding dynamic contact angle. Consistent with the current understanding of wetting dynamics, film recession is faster on the more poorly wetted surface to an extent that cannot be explained solely by the increase in the surface tension driving force. In addition, the rates of recession of the thinnest films are found to increase with decreasing film thickness. These new results imply not only that the mobility of the liquid molecules adjacent to the solid increases with decreasing solid-liquid interactions, but also that the mobility adjacent to the free surface of the film is higher than in the bulk, so that the effective viscosity of the film decreases with thickness.
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Affiliation(s)
- E Bertrand
- Centre for Research in Molecular Modelling, University of Mons-Hainaut, Parc Initialis, Av. Copernic 1, 7000 Mons, Belgium.
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31
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Vilmin T, Raphaël E. Dewetting of thin polymer films. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 21:161-74. [PMID: 17146593 DOI: 10.1140/epje/i2006-10057-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 11/09/2006] [Indexed: 05/12/2023]
Abstract
We study the dewetting of thin polymer films deposited on slippery substrate. Recent experiments on these systems have revealed many unexpected features. We develop here a model that takes into account the rheological properties of polymer melts, focussing on two dewetting geometries (the receding of a straight edge, and the opening of a hole). We show that the friction law associated with the slippage between the film and the substrate has a direct influence on the dewetting dynamic. In addition, we demonstrate that residual stresses, which can be stored in the films due to their viscoelasticity, are a source of destabilization for polymer films, and accelerate the dewetting process.
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Affiliation(s)
- T Vilmin
- Laboratoire de Physico-Chimie Théorique, UMR CNRS 7083, ESPCI, 10 rue Vauquelin, 75231, Paris Cedex 05, France.
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32
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Carroll GT, Sojka ME, Lei X, Turro NJ, Koberstein JT. Photoactive additives for cross-linking polymer films: Inhibition of dewetting in thin polymer films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:7748-54. [PMID: 16922559 DOI: 10.1021/la0611099] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In this report, we describe a versatile photochemical method for cross-linking polymer films and demonstrate that this method can be used to inhibit thin polymer films from dewetting. A bifunctional photoactive molecule featuring two benzophenone chromophores capable of abstracting hydrogen atoms from various donors, including C-H groups, is mixed into PS films. Upon exposure to UV light, the bis-benzophenone molecule cross-links the chains presumably by hydrogen abstraction followed by radical recombination. Photoinduced cross-linking is characterized by infrared spectroscopy and gel permeation chromatography. Optical and atomic force microscopy images show that photocrosslinked polystyrene (PS) thin films resist dewetting when heated above the glass transition temperature or exposed to solvent vapor. PS films are inhibited from dewetting on both solid and liquid substrates. The effectiveness of the method to inhibit dewetting is studied as a function of the ratio of cross-linker to macromolecule, duration of exposure to UV light, film thickness, the driving force for dewetting, and the thermodynamic nature of the substrate.
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Affiliation(s)
- Gregory T Carroll
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3157, New York, New York 10027, USA
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33
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Jones RL, Hu T, Soles CL, Lin EK, Reano RM, Pang SW, Casa DM. Real-time shape evolution of nanoimprinted polymer structures during thermal annealing. NANO LETTERS 2006; 6:1723-8. [PMID: 16895363 DOI: 10.1021/nl061086i] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The real-time shape evolution of nanoimprinted polymer patterns is measured as a function of annealing time and temperature using critical dimension small-angle X-ray scattering (CD-SAXS). Periodicity, line width, line height, and sidewall angle are reported with nanometer resolution for parallel line/space patterns in poly(methyl methacrylate) (PMMA) both below and above the bulk glass transition temperature (T(G)). Heating these patterns below T(G) does not produce significant thermal expansion, at least to within the resolution of the measurement. However, above T(G) the fast rate of loss in pattern size at early times transitions to a reduced rate in longer time regimes. The time-dependent rate of polymer flow from the pattern into the underlying layer, termed pattern "melting", is consistent with a model of elastic recovery from stresses induced by the molding process.
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Affiliation(s)
- Ronald L Jones
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
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34
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Gabriele S, Sclavons S, Reiter G, Damman P. Disentanglement time of polymers determines the onset of rim instabilities in dewetting. PHYSICAL REVIEW LETTERS 2006; 96:156105. [PMID: 16712174 DOI: 10.1103/physrevlett.96.156105] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 03/08/2006] [Indexed: 05/09/2023]
Abstract
Molecular relaxations determine the viscoelastic properties of polymers, which, in turn, control macroscopic processes like dewetting. Here, we demonstrate experimentally that the onset of rim instabilities is correlated with the longest relaxation ("reptation") time of the dewetting polymer. Conversely, such experiments allow us to determine the reptation time of polystyrene in thin films as a function of molecular weight. Our approach opens up new possibilities for testing rheological properties of polymers confined in thin films.
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Affiliation(s)
- Sylvain Gabriele
- Laboratoire de Physicochimie des Polymères, Materia Nova asbl, Parc Initialis, 1, Avenue N. Copernic, B-7000 Mons, Belgium
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35
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Yang MH, Hou SY, Chang YL, Yang ACM. Molecular recoiling in polymer thin film dewetting. PHYSICAL REVIEW LETTERS 2006; 96:066105. [PMID: 16606016 DOI: 10.1103/physrevlett.96.066105] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2005] [Indexed: 05/08/2023]
Abstract
The molecular recoiling force stemming from nonequilibrium chain conformation was found to play a very important role in the dewetting stability of polymer thin films. Correct measurements and inclusion of this molecular force into thermodynamic consideration are crucial for analyzing dewetting phenomena and nanoscale polymer chain physics. This force was measured using a simple method based on contour relaxation at the incipient dewetting holes. The recoiling stress was found to increase dramatically with molecular weight and decreasing film thickness. The corresponding forces were calculated to be in the range from 9.0 to 28.2 mN/m, too large to be neglected when compared to the dispersive forces (approximately 10 mN/m) commonly operative in thin polymer films.
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Affiliation(s)
- M H Yang
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan
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36
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Bodiguel H, Fretigny C. Viscoelastic dewetting of a polymer film on a liquid substrate. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 19:185-93. [PMID: 16491310 DOI: 10.1140/epje/e2006-00021-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Indexed: 05/06/2023]
Abstract
The Dewetting of thin polymer films (60-300 nm) on a non-wettable liquid substrate has been studied in the vicinity of their glass transition temperature. In our experiment, we observe a global contraction of the film while its thickness remains uniform. We show that, in this case, the strain corresponds to simple extension, and we verify that it is linear with the stress applied by the surface tension. This allows direct measurement of the stress/strain response as a function of time, and thus permits the measurement of an effective compliance of the thin films. It is, however, difficult to obtain a complete viscoelastic characterization, as the short time response is highly dependant on the physical age of the sample. Experimental results underline the effects of residual stress and friction when dewetting is analyzed on rigid substrates.
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Affiliation(s)
- H Bodiguel
- ESPCI, Laboratoire de Physico-Chimie des Polymères et des Milieux Dispersés, CNRS UMR 7615, 10 rue Vauquelin, 75231, Paris Cedex 05, France
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37
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Gabriele S, Damman P, Sclavons S, Desprez S, Coppée S, Reiter G, Hamieh M, Akhrass SA, Vilmin T, Raphaël E. Viscoelastic dewetting of constrained polymer thin films. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20919] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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38
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39
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Reiter G, Hamieh M, Damman P, Sclavons S, Gabriele S, Vilmin T, Raphaël E. Residual stresses in thin polymer films cause rupture and dominate early stages of dewetting. NATURE MATERIALS 2005; 4:754-8. [PMID: 16184173 DOI: 10.1038/nmat1484] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Accepted: 08/11/2005] [Indexed: 05/04/2023]
Abstract
In attempting to reduce the size of functional devices, the thickness of polymer films has reached values even smaller than the diameter of the unperturbed molecule. However, despite enormous efforts for more than a decade, our understanding of the origin of some puzzling properties of such thin films is still not satisfactory and several peculiar observations remain mysterious. For example, under certain conditions, such films show negative expansion coefficients or show undesirable rupture although energetically they are expected to be stable. Here, we demonstrate that many of these extraordinary effects can be related to residual stresses within the film, resulting from the preparation of these films from solution by fast evaporation of the solvent. Consequently, depending on thermal history and ageing time, such films show significant changes even in the glassy state, which we quantify by dewetting experiments and corresponding theoretical studies. Identifying the relevance of frozen-in polymer conformations gives us a handle for manipulating and controlling properties of nanometric thin polymer films.
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Affiliation(s)
- Günter Reiter
- Institut de Chimie des Surfaces et Interfaces, CNRS-UHA, 15, rue Jean Starcky, BP 2488, 68057 Mulhouse Cedex, France.
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40
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Roth CB, Dutcher JR. Hole growth in freely standing polystyrene films probed using a differential pressure experiment. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:021803. [PMID: 16196593 DOI: 10.1103/physreve.72.021803] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Revised: 04/19/2005] [Indexed: 05/04/2023]
Abstract
We have probed the whole chain mobility of polymer molecules confined to freely standing films by measuring the flow of gas through holes growing in the films at elevated temperatures using a differential pressure experiment. Freely standing polystyrene films were measured for the temperature range 92 degrees C<T<105 degrees C for films with two different molecular weights Mw=717 x 10(3) and 2240 x 10(3) , with thicknesses 51 nm<h<97 nm . This range of film thicknesses is of particular interest because large reductions in the glass transition temperature Tg have been measured previously for freely standing PS films in this thickness range. We find that hole formation and growth, and therefore substantial chain mobility, does not occur until temperatures close to the bulk value of the glass transition temperature T(bulk)g. The characteristic growth times tau for the thinnest films, which have reduced values of Tg, are not substantially less than those for thicker films, and we find that these small differences in tau can be understood in terms of the bulk phenomenon of shear thinning. We also show that the viscosity at the edge of the hole inferred from the characteristic growth times obtained in this and previous studies exhibit shear thinning with reduced shear strain rates beta that span twelve orders of magnitude.
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Affiliation(s)
- C B Roth
- Department of Physics and the Guelph-Waterloo Physics Institute, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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41
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Roth CB, Deh B, Nickel BG, Dutcher JR. Evidence of convective constraint release during hole growth in freely standing polystyrene films at low temperatures. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:021802. [PMID: 16196592 DOI: 10.1103/physreve.72.021802] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Revised: 04/25/2005] [Indexed: 05/04/2023]
Abstract
Hole growth measurements were performed using optical microscopy on freely standing polystyrene films at temperatures that were slightly larger than the bulk value of the glass transition temperature T(bulk)g. For the measured range of temperatures, we have observed a transition from linear growth of the hole radius R during the early stages to exponential growth of R at later times. We have characterized this transition as a function of molecular weight 120 x 10(3) < Mw <2240 x 10(3) , film thickness 61 nm<h<125 nm , and temperature 101 degrees C<T<117 degrees C . The viscosity at the edge of the hole inferred from the long time exponential growth regime exhibits shear thinning due to the large shear strain rates present at the edge of the hole. The R (t) data for all times can be fit very well using an expression that describes exponential hole growth with a time-dependent viscosity that allows for an initial, transient response due to the decay of elastic entanglements. The time scale for the decay of the transient behavior is interpreted in terms of the decay of entanglements by the convective constraint release mechanism of the tube theory of entangled polymer dynamics.
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Affiliation(s)
- C B Roth
- Department of Physics and the Guelph-Waterloo Physics Institute, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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42
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Xavier JH, Li C, Rafailovich MH, Sokolov J. Dynamics of ultrathin films in the glassy state. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:5069-72. [PMID: 15896052 DOI: 10.1021/la046776l] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We report hole growth experiments in free-standing polystyrene (PS) films at temperatures up to 10 degrees C below the bulk glass transition. The data show an unexpected result: the growth rate of nucleated holes increases with increasing molecular weight, up to a limiting value beyond which the rate is approximately constant. Film thicknesses of 45, 80, and 100 nm were studied, using PS molecular weights ranging from 65K to 11.4 Mg/mol. Hole diameters grew linearly with time, and no growing rims were observed to form around the developing holes. Possible explanations in terms of elasticity, yield, and influence of sample preparation and confinement effects are discussed.
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Affiliation(s)
- J H Xavier
- Department of Materials Science and Engineering, SUNY at Stony Brook, Stony Brook, New York 11794, USA.
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43
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Turchanin A, Tsekov R, Freyland W. Oscillatory wetting instability induced by liquid–liquid decomposition in a Ga–Pb alloy. J Chem Phys 2004; 120:11171-82. [PMID: 15268147 DOI: 10.1063/1.1737306] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present the first experimental investigation and pertinent theoretical modeling of an interfacial oscillatory instability in a binary fluid alloy, the Ga-Pb system. It is characterized by spinodal decomposition at elevated temperatures and by a complete wetting transition at liquid-liquid coexistence. For the alloy Ga(0.95)Pb(0.05) the fluid interface has been probed by second harmonic generation (SHG) under UHV conditions at temperatures between 740 and 550 K. At conditions inside the miscibility gap clear oscillations of the SHG-intensity with a period of approximately 30 min are found for different cooling cycles and also at constant temperatures. These interfacial oscillatory instabilities simultaneously induce temperature oscillations in the bulk fluid with the same period. This phenomenon can be explained by a periodic variation of the fluid interfacial emissivity. A model has been developed which describes the wetting-dewetting dynamics by hydrodynamic equations within the Reynolds approximation. It is found that the interfacial oscillatory instability is determined by capillary-gravitation instability. The model quantitatively describes the time evolution of the interfacial and temperature oscillations and gives the correct value of the oscillation period. A detailed comparison of the experimental and model results is given.
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Affiliation(s)
- A Turchanin
- Institute of Physical Chemistry, Physical Chemistry of Condensed Matter, University of Karlsruhe, D-76128 Karlsruhe, Germany
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