1
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Kyropoulou M, Yorulmaz Avsar S, Schoenenberger CA, Palivan CG, Meier WP. From spherical compartments to polymer films: exploiting vesicle fusion to generate solid supported thin polymer membranes. NANOSCALE 2021; 13:6944-6952. [PMID: 33885496 DOI: 10.1039/d1nr01122g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Solid supported polymer membranes as scaffold for the insertion of functional biomolecules provide the basis for mimicking natural membranes. They also provide the means for unraveling biomolecule-membrane interactions and engineering platforms for biosensing. Vesicle fusion is an established procedure to obtain solid supported lipid bilayers but the more robust polymer vesicles tend to resist fusion and planar membranes rarely form. Here, we build on vesicle fusion to develop a refined and efficient way to produce solid supported membranes based on poly(dimethylsiloxane)-poly(2-methyl-2-oxazoline) (PMOXA-b-PDMS-b-PMOXA) amphiphilic triblock copolymers. We first create thiol-bearing polymer vesicles (polymersomes) and anchor them on a gold substrate. An osmotic shock then provokes polymersome rupture and drives planar film formation. Prerequisite for a uniform amphiphilic planar membrane is the proper combination of immobilized polymersomes and osmotic shock conditions. Thus, we explored the impact of the hydrophobic PDMS block length of the polymersome on the formation and the characteristics of the resulting solid supported polymer assemblies by quarz crystal microbalance with dissipation monitoring (QCM-D), atomic force microscopy (AFM) and spectroscopic ellipsometry (SE). When the PDMS block is short enough, attached polymersomes restructure in response to osmotic shock, resulting in a uniform planar membrane. Our approach to rapidly form planar polymer membranes by vesicle fusion brings many advantages to the development of synthetic planar membranes for bio-sensing and biotechnological applications.
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Affiliation(s)
- Myrto Kyropoulou
- Department of Chemistry, University of Basel, Mattenstrasse 24a, BPR 1096, 4058 Basel, Switzerland.
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2
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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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3
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Barra V, Afkhami S, Kondic L. Thin viscoelastic dewetting films of Jeffreys type subjected to gravity and substrate interactions. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:12. [PMID: 30687884 DOI: 10.1140/epje/i2019-11774-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 01/04/2019] [Indexed: 06/09/2023]
Abstract
This work presents a study of the interfacial dynamics of thin viscoelastic films subjected to the gravitational force and substrate interactions induced by the disjoining pressure, in two spatial dimensions. The governing equation is derived as a long-wave approximation of the Navier-Stokes equations for incompressible viscoelastic liquids under the effect of gravity, with the Jeffreys model for viscoelastic stresses. For the particular cases of horizontal or inverted planes, the linear stability analysis is performed to investigate the influence of the physical parameters involved on the growth rate and length scales of instabilities. Numerical simulations of the nonlinear regime of the dewetting process are presented for the particular case of an inverted plane. Both gravity and the disjoining pressure are found to affect not only the length scale of instabilities, but also the final configuration of dewetting, by favoring the formation of satellite droplets, that are suppressed by the slippage with the solid substrate.
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Affiliation(s)
- Valeria Barra
- Department of Mathematical Sciences, New Jersey Institute of Technology, 07102, Newark, NJ, USA
| | - Shahriar Afkhami
- Department of Mathematical Sciences, New Jersey Institute of Technology, 07102, Newark, NJ, USA.
| | - Lou Kondic
- Department of Mathematical Sciences, New Jersey Institute of Technology, 07102, Newark, NJ, USA
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4
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Impact of energy dissipation on interface shapes and on rates for dewetting from liquid substrates. Sci Rep 2018; 8:13295. [PMID: 30185914 PMCID: PMC6125481 DOI: 10.1038/s41598-018-31418-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 08/16/2018] [Indexed: 11/30/2022] Open
Abstract
We revisit the fundamental problem of liquid-liquid dewetting and perform a detailed comparison of theoretical predictions based on thin-film models with experimental measurements obtained by atomic force microscopy. Specifically, we consider the dewetting of a liquid polystyrene layer from a liquid polymethyl methacrylate layer, where the thicknesses and the viscosities of both layers are similar. Using experimentally determined system parameters like viscosity and surface tension, an excellent agreement of experimentally and theoretically obtained rim profile shapes are obtained including the liquid-liquid interface and even dewetting rates. Our new energetic approach additionally allows to assess the physical importance of different contributions to the energy-dissipation mechanism, for which we analyze the local flow fields and the local dissipation rates. Using this approach, we explain why dewetting rates for liquid-liquid systems follow no universal power law, despite the fact that experimental velocities are almost constant. This is in contrast to dewetting scenarios on solid substrates and in contrast to previous results for liquid-liquid substrates using heuristic approaches.
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5
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Schulman RD, Niven JF, Hack MA, DiMaria C, Dalnoki-Veress K. Liquid dewetting under a thin elastic film. SOFT MATTER 2018; 14:3557-3562. [PMID: 29682670 DOI: 10.1039/c8sm00255j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We study the dewetting of liquid films capped by a thin elastomeric layer. When the tension in the elastomer is isotropic, circular holes grow at a rate which decreases with increasing tension. The morphology of holes and rim stability can be controlled by changing the boundary conditions and tension in the capping film. When the capping film is prepared with a biaxial tension, holes form with a non-circular shape elongated along the high tension axis. With suitable choice of elastic boundary conditions, samples can even be designed such that square holes appear.
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Affiliation(s)
- Rafael D Schulman
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4M1, Canada.
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6
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Ilton M, Salez T, Fowler PD, Rivetti M, Aly M, Benzaquen M, McGraw JD, Raphaël E, Dalnoki-Veress K, Bäumchen O. Adsorption-induced slip inhibition for polymer melts on ideal substrates. Nat Commun 2018; 9:1172. [PMID: 29563496 PMCID: PMC5862909 DOI: 10.1038/s41467-018-03610-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 02/28/2018] [Indexed: 11/25/2022] Open
Abstract
Hydrodynamic slip, the motion of a liquid along a solid surface, represents a fundamental phenomenon in fluid dynamics that governs liquid transport at small scales. For polymeric liquids, de Gennes predicted that the Navier boundary condition together with polymer reptation implies extraordinarily large interfacial slip for entangled polymer melts on ideal surfaces; this Navier-de Gennes model was confirmed using dewetting experiments on ultra-smooth, low-energy substrates. Here, we use capillary leveling—surface tension driven flow of films with initially non-uniform thickness—of polymeric films on these same substrates. Measurement of the slip length from a robust one parameter fit to a lubrication model is achieved. We show that at the low shear rates involved in leveling experiments as compared to dewetting ones, the employed substrates can no longer be considered ideal. The data is instead consistent with a model that includes physical adsorption of polymer chains at the solid/liquid interface. When modeling fluid flow over a solid surface, one must determine the slip velocity at the boundary. Here Ilton et al. perform experiments to quantify the slip length of polymer melts at a nearly ideal solid surface and capture them in a model involving the density of physically adsorbed polymer chains.
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Affiliation(s)
- Mark Ilton
- Department of Physics & Astronomy, McMaster University, Hamilton, ON, L8S 4M1, Canada.,Polymer Science & Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Thomas Salez
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, 33405, Talence, France.,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Hokkaido, 060-0808, Japan.,Laboratoire de Physico-Chimie Théorique, UMR CNRS Gulliver 7083, ESPCI Paris, PSL Research University, 75005, Paris, France
| | - Paul D Fowler
- Department of Physics & Astronomy, McMaster University, Hamilton, ON, L8S 4M1, Canada.,Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Faßberg 17, 37077, Göttingen, Germany
| | - Marco Rivetti
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Faßberg 17, 37077, Göttingen, Germany
| | - Mohammed Aly
- Département de Physique, Ecole Normale Supérieure/PSL Research University, CNRS, 24 Rue Lhomond, 75005, Paris, France
| | - Michael Benzaquen
- Laboratoire de Physico-Chimie Théorique, UMR CNRS Gulliver 7083, ESPCI Paris, PSL Research University, 75005, Paris, France.,Ladhyx, UMR CNRS 7646, Ecole Polytechnique, 91128, Palaiseau Cedex, France
| | - Joshua D McGraw
- Department of Physics & Astronomy, McMaster University, Hamilton, ON, L8S 4M1, Canada.,Département de Physique, Ecole Normale Supérieure/PSL Research University, CNRS, 24 Rue Lhomond, 75005, Paris, France
| | - Elie Raphaël
- Laboratoire de Physico-Chimie Théorique, UMR CNRS Gulliver 7083, ESPCI Paris, PSL Research University, 75005, Paris, France
| | - Kari Dalnoki-Veress
- Department of Physics & Astronomy, McMaster University, Hamilton, ON, L8S 4M1, Canada.,Laboratoire de Physico-Chimie Théorique, UMR CNRS Gulliver 7083, ESPCI Paris, PSL Research University, 75005, Paris, France
| | - Oliver Bäumchen
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Faßberg 17, 37077, Göttingen, Germany.
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Hall AR, Geoghegan M. Polymers and biopolymers at interfaces. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:036601. [PMID: 29368695 DOI: 10.1088/1361-6633/aa9e9c] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
This review updates recent progress in the understanding of the behaviour of polymers at surfaces and interfaces, highlighting examples in the areas of wetting, dewetting, crystallization, and 'smart' materials. Recent developments in analysis tools have yielded a large increase in the study of biological systems, and some of these will also be discussed, focussing on areas where surfaces are important. These areas include molecular binding events and protein adsorption as well as the mapping of the surfaces of cells. Important techniques commonly used for the analysis of surfaces and interfaces are discussed separately to aid the understanding of their application.
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Affiliation(s)
- A R Hall
- Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, United Kingdom. Fraunhofer Project Centre for Embedded Bioanalytical Systems, Dublin City University, Glasnevin, Dublin 9, Ireland
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8
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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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9
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Xu L, Bandyopadhyay D, Reddy PDS, Sharma A, Joo SW. Giant Slip Induced Anomalous Dewetting of an Ultrathin Film on a Viscous Sublayer. Sci Rep 2017; 7:14776. [PMID: 29116103 PMCID: PMC5676695 DOI: 10.1038/s41598-017-14861-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/25/2017] [Indexed: 11/23/2022] Open
Abstract
A 'giant' slip dynamics was engineered to a highly confined interface of a dewetting polymethylmethacrylate (PMMA) ultrathin film by introducing a lubricating viscous polystyrene (PS) sublayer. The crossover of regimes from no-slip to giant-slip was engendered by tuning the viscosity and thickness of the sublayer. A long-range hole-rim interaction with increase in slippage on the PMMA-PS interface transformed the circular holes on the PMMA surface into the noncircular faceted ones. The extent of the slippage and the transition of the length scales from slip-dominated to no-slip regime were evaluated using a general linear stability analysis. The proposed formulation provided an analytical tool to evaluate the slippage effective at the soft and deformable liquid-liquid interfaces.
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Affiliation(s)
- Lin Xu
- Laboratory of Surface Physics and Chemistry, Guizhou Education University, Guiyang, 550018, P. R. China
| | - Dipankar Bandyopadhyay
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781039, India.
| | | | - Ashutosh Sharma
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
| | - Sang Woo Joo
- School of Mechanical Engineering, Yeungnam University, Gyongsan, 712-749, South Korea.
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10
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McGraw JD, Klos M, Bridet A, Hähl H, Paulus M, Castillo JM, Horsch M, Jacobs K. Influence of bidisperse self-assembled monolayer structure on the slip boundary condition of thin polymer films. J Chem Phys 2017; 146:203326. [DOI: 10.1063/1.4978676] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Joshua D. McGraw
- Soft Matter Physics Group, Experimental Physics, Saarland University, 66041 Saarbrücken, Germany
- Département de Physique, Ecole Normale Supérieure/PSL Research University, CNRS, 24 Rue Lhomond, 75005 Paris, France
| | - Mischa Klos
- Soft Matter Physics Group, Experimental Physics, Saarland University, 66041 Saarbrücken, Germany
| | - Antoine Bridet
- Soft Matter Physics Group, Experimental Physics, Saarland University, 66041 Saarbrücken, Germany
| | - Hendrik Hähl
- Soft Matter Physics Group, Experimental Physics, Saarland University, 66041 Saarbrücken, Germany
| | - Michael Paulus
- Fakultät Physik/DELTA, TU Dortmund, 44221 Dortmund, Germany
| | - Juan Manuel Castillo
- Laboratory of Engineering Thermodynamics, University of Kaiserslautern, Erwin-Schrödinger-Strasse 44, 67663 Kaiserslautern, Germany
| | - Martin Horsch
- Laboratory of Engineering Thermodynamics, University of Kaiserslautern, Erwin-Schrödinger-Strasse 44, 67663 Kaiserslautern, Germany
| | - Karin Jacobs
- Soft Matter Physics Group, Experimental Physics, Saarland University, 66041 Saarbrücken, Germany
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11
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Kotni TR, Khanna R, Sarkar J. Kinetics of sub-spinodal dewetting of thin films of thickness dependent viscosity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:175001. [PMID: 28333683 DOI: 10.1088/1361-648x/aa62d9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An alternative explanation of the time varying and very low growth exponents in dewetting of polymer films like polystyrene films is presented based on non-linear simulations. The kinetics of these films is explored within the framework of experimentally observed thickness dependent viscosity. These films exhibit sub-spinodal dewetting via formation of satellite holes in between primary dewetted holes under favorable conditions of excess intermolecular forces and film thicknesses. We find that conditions responsible for sub-spinodal dewetting concurrently lead to remarkable changes in the kinetics of dewetting of even primary holes. For example, the radius of the hole grows in time with a power-law growth exponent sequence of [Formula: see text], in contrast to the usual ∼4/5. This is due to the cumulative effect of reduced rim mobility due to thickness dependent viscosity and hindrance created by satellite holes.
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12
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13
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Abstract
Classical hydrodynamic models predict that infinite work is required to move a three-phase contact line, defined here as the line where a liquid/vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap-shaped polystyrene microdroplets, with nonequilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using in situ atomic force microscopy. We find that slip has a strong influence on the droplet evolutions, both on the transient nonspherical shapes and contact line dynamics. The observations are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition.
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14
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Sabzevari SM, McGraw JD, Wood-Adams P. Short chains enhance slip of highly entangled polystyrenes during thin film dewetting. RSC Adv 2016. [DOI: 10.1039/c6ra15606a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We investigate the effect of short chains on slip of highly entangled polystyrenes (PS) during thin film dewetting from non-wetting fluorinated surfaces.
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Affiliation(s)
- S. Mostafa Sabzevari
- Department of Mechanical and Industrial Engineering
- Concordia University
- Montreal
- Canada
| | - Joshua D. McGraw
- Soft Matter Physics Group
- Experimental Physics
- Saarland University
- 66041 Saarbrücken
- Germany
| | - Paula Wood-Adams
- Department of Mechanical and Industrial Engineering
- Concordia University
- Montreal
- Canada
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15
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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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16
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Wong I, Teo GH, Neto C, Thickett SC. Micropatterned Surfaces for Atmospheric Water Condensation via Controlled Radical Polymerization and Thin Film Dewetting. ACS APPLIED MATERIALS & INTERFACES 2015; 7:21562-21570. [PMID: 26372163 DOI: 10.1021/acsami.5b06856] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Inspired by an example found in nature, the design of patterned surfaces with chemical and topographical contrast for the collection of water from the atmosphere has been of intense interest in recent years. Herein we report the synthesis of such materials via a combination of macromolecular design and polymer thin film dewetting to yield surfaces consisting of raised hydrophilic bumps on a hydrophobic background. RAFT polymerization was used to synthesize poly(2-hydroxypropyl methacrylate) (PHPMA) of targeted molecular weight and low dispersity; spin-coating of PHPMA onto polystyrene films produced stable polymer bilayers under appropriate conditions. Thermal annealing of these bilayers above the glass transition temperature of the PHPMA layer led to complete dewetting of the top layer and the formation of isolated PHPMA domains atop the PS film. Due to the vastly different rates of water nucleation on the two phases, preferential dropwise nucleation of water occurred on the PHPMA domains, as demonstrated by optical microscopy. The simplicity of the preparation method and ability to target polymers of specific molecular weight demonstrate the value of these materials with respect to large-scale water collection devices or other materials science applications where patterning is required.
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Affiliation(s)
- Ian Wong
- Centre for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Guo Hui Teo
- Centre for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia
- School of Physical Sciences (Chemistry), The University of Tasmania , Sandy Bay, Tasmania 7005, Australia
| | - Chiara Neto
- School of Chemistry F11, The University of Sydney , Sydney, New South Wales 2006, Australia
| | - Stuart C Thickett
- Centre for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia
- School of Physical Sciences (Chemistry), The University of Tasmania , Sandy Bay, Tasmania 7005, Australia
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17
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Kotni TR, Sarkar J, Khanna R. Kinetically engendered subspinodal length scales in spontaneous dewetting of thin liquid films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:020401. [PMID: 25215673 DOI: 10.1103/physreve.90.020401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Indexed: 06/03/2023]
Abstract
Numerical simulations reveal emergence of subspinodal length scales in spontaneous dewetting of nonslipping unstable thin liquid films on homogeneous substrates if the liquid viscosity decreases with decrease in film thickness.
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Affiliation(s)
- Tirumala Rao Kotni
- Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi-110016, India
| | - Jayati Sarkar
- Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi-110016, India
| | - Rajesh Khanna
- Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi-110016, India
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18
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McGraw JD, Bäumchen O, Klos M, Haefner S, Lessel M, Backes S, Jacobs K. Nanofluidics of thin polymer films: linking the slip boundary condition at solid-liquid interfaces to macroscopic pattern formation and microscopic interfacial properties. Adv Colloid Interface Sci 2014; 210:13-20. [PMID: 24780402 DOI: 10.1016/j.cis.2014.03.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 03/28/2014] [Accepted: 03/28/2014] [Indexed: 10/25/2022]
Abstract
If a thin liquid film is not stable, different rupture mechanisms can be observed causing characteristic film morphologies: spinodal dewetting and dewetting by nucleation of holes. This rupturing entails liquid flow and opens new possibilities to study microscopic phenomena. Here we use this process of dewetting to gain insight on the slip boundary condition at the solid-liquid interface. Having established hydrodynamic models that allow for the determination of the slip length in a dewetting experiment based on nucleation, we move on to the quantification and molecular description of slip effects in various systems. For the late stage of the dewetting process involving the Rayleigh-Plateau instability, several distinct droplet patterns can be observed. We describe the importance of slip in determining what pattern may be found. In order to control the slip length, we use polymeric liquids on different hydrophobic coatings of silicon wafers. We find that subtle changes in the coating can lead to large changes in the slip length. Thus, we gain insight into the question of how the structure of the substrate affects the slip length.
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19
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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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20
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Bäumchen O, Benzaquen M, Salez T, McGraw JD, Backholm M, Fowler P, Raphaël E, Dalnoki-Veress K. Relaxation and intermediate asymptotics of a rectangular trench in a viscous film. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:035001. [PMID: 24125391 DOI: 10.1103/physreve.88.035001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Indexed: 06/02/2023]
Abstract
The surface of a thin liquid film with nonconstant curvature flattens as a result of capillary forces. While this leveling is driven by local curvature gradients, the global boundary conditions greatly influence the dynamics. Here, we study the evolution of rectangular trenches in a polystyrene nanofilm. Initially, when the two sides of a trench are well separated, the asymmetric boundary condition given by the step height controls the dynamics. In this case, the evolution results from the leveling of two noninteracting steps. As the steps broaden further and start to interact, the global symmetric boundary condition alters the leveling dynamics. We report on full agreement between theory and experiments for the capillary-driven flow and resulting time dependent height profiles, a crossover in the power-law dependence of the viscous energy dissipation as a function of time as the trench evolution transitions from two noninteracting to interacting steps, and the convergence of the profiles to a universal self-similar attractor that is given by the Green's function of the linear operator describing the dimensionless linearized thin film equation.
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Affiliation(s)
- Oliver Bäumchen
- Department of Physics and Astronomy and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, Canada
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21
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Gutfreund P, Bäumchen O, Fetzer R, van der Grinten D, Maccarini M, Jacobs K, Zabel H, Wolff M. Solid surface structure affects liquid order at the polystyrene-self-assembled-monolayer interface. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:012306. [PMID: 23410330 DOI: 10.1103/physreve.87.012306] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 11/22/2012] [Indexed: 06/01/2023]
Abstract
We present a combined x-ray and neutron reflectivity study characterizing the interface between polystyrene (PS) and silanized surfaces. Motivated by the large difference in slip velocity of PS on top of dodecyl-trichlorosilane (DTS) and octadecyl-trichlorosilane (OTS) found in previous studies, these two systems were chosen for the present investigation. The results reveal the molecular conformation of PS on silanized silicon. Differences in the molecular tilt of OTS and DTS are replicated by the adjacent phenyl rings of the PS. We discuss our findings in terms of a potential link between the microscopic interfacial structure and dynamic properties of polymeric liquids at interfaces.
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22
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Nguyen TD, Fuentes-Cabrera M, Fowlkes JD, Diez JA, González AG, Kondic L, Rack PD. Competition between collapse and breakup in nanometer-sized thin rings using molecular dynamics and continuum modeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:13960-13967. [PMID: 22957759 DOI: 10.1021/la303093f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We consider nanometer-sized fluid annuli (rings) deposited on a solid substrate and ask whether these rings break up into droplets due to the instability of Rayleigh-Plateau-type modified by the presence of the substrate, or collapse to a central drop due to the presence of azimuthal curvature. The analysis is carried out by a combination of atomistic molecular dynamics simulations and a continuum model based on a long-wave limit of Navier-Stokes equations. We find consistent results between the two approaches, and demonstrate characteristic dimension regimes which dictate the assembly dynamics.
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Affiliation(s)
- Trung Dac Nguyen
- National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
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23
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Léonforte F, Müller M. Statics of polymer droplets on deformable surfaces. J Chem Phys 2011; 135:214703. [DOI: 10.1063/1.3663381] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Léonforte F, Servantie J, Pastorino C, Müller M. Molecular transport and flow past hard and soft surfaces: computer simulation of model systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:184105. [PMID: 21508476 DOI: 10.1088/0953-8984/23/18/184105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The equilibrium and flow of polymer films and drops past a surface are characterized by the interface and surface tensions, viscosity, slip length and hydrodynamic boundary position. These parameters of the continuum description are extracted from molecular simulations of coarse-grained models. Hard, corrugated substrates are modelled by a Lennard-Jones solid while polymer brushes are studied as prototypes of soft, deformable surfaces. Four observations are discussed. (i) If the surface becomes strongly attractive or is coated with a brush, the Navier boundary condition fails to describe the effect of the surface independently of the strength and type of the flow. This failure stems from the formation of a boundary layer with an effective, higher viscosity. (ii) In the case of brush-coated surfaces, flow induces a cyclic, tumbling motion of the tethered chain molecules. Their collective motion gives rise to an inversion of the flow in the vicinity of the grafting surfaces and leads to strong, non-Gaussian fluctuations of the molecular orientations. The flow past a polymer brush cannot be described by Brinkman's equation. (iii) The hydrodynamic boundary condition is an important parameter for predicting the motion of polymer droplets on a surface under the influence of an external force. Their steady-state velocity is dictated by a balance between the power that is provided by the external force and the dissipation. If there is slippage at the liquid-solid interface, the friction at the solid-liquid interface and the viscous dissipation of the flow inside the drop will be the dominant dissipation mechanisms; dissipation at the three-phase contact line appears to be less important on a hard surface. (iv) On a soft, deformable substrate like a polymer brush, we observe a lifting-up of the three-phase contact line. Controlling the grafting density and the incompatibility between the brush and the polymer liquid we can independently tune the softness of the surface and the contact angle and thereby identify the parameters for maximizing the deformation at the three-phase contact.
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Affiliation(s)
- F Léonforte
- Institut für Theoretische Physik, Georg-August-Universität, 37077 Göttingen, Germany
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25
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Seemann R, Brinkmann M, Herminghaus S, Khare K, Law BM, McBride S, Kostourou K, Gurevich E, Bommer S, Herrmann C, Michler D. Wetting morphologies and their transitions in grooved substrates. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:184108. [PMID: 21508471 DOI: 10.1088/0953-8984/23/18/184108] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
When exposed to a partially wetting liquid, many natural and artificial surfaces equipped with complex topographies display a rich variety of liquid interfacial morphologies. In the present article, we focus on a few simple paradigmatic surface topographies and elaborate on the statics and dynamics of the resulting wetting morphologies. It is demonstrated that the spectrum of wetting morphologies increases with increasing complexity of the groove structure. On elastically deformable substrates, additional structures in the liquid morphologies can be observed, which are caused by deformations of the groove geometry in the presence of capillary forces. The emergence of certain liquid morphologies in grooves can be actively controlled by changes in wettability and geometry. For electrically conducting solid substrates, the apparent contact angle can be varied by electrowetting. This allows, depending on groove geometry, a reversible or irreversible transport of liquid along surface grooves. In the case of irreversible liquid transport in triangular grooves, the dynamics of the emerging instability is sensitive to the apparent hydrodynamic slip at the substrate. On elastic substrates, the geometry can be varied in a straightforward manner by stretching or relaxing the sample. The imbibition velocity in deformable grooves is significantly reduced compared to solid grooves, which is a result of the microscopic deformation of the elastic groove material close to the three phase contact line.
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Affiliation(s)
- Ralf Seemann
- Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany.
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26
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Münch A, Wagner B. Impact of slippage on the morphology and stability of a dewetting rim. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:184101. [PMID: 21508486 DOI: 10.1088/0953-8984/23/18/184101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this study lubrication theory is used to describe the stability and morphology of the rim that forms as a thin polymer film dewets from a hydrophobized silicon wafer. Thin film equations are derived from the governing hydrodynamic equations for the polymer to enable the systematic mathematical and numerical analysis of the properties of the solutions for different regimes of slippage and for a range of timescales. Dewetting rates and the cross sectional profiles of the evolving rims are derived for these models and compared to experimental results. Experiments also show that the rim is typically unstable in the spanwise direction and develops thicker and thinner parts that may grow into 'fingers'. Linear stability analysis as well as nonlinear numerical solutions are presented to investigate shape and growth rate of the rim instability. It is demonstrated that the difference in morphology and the rate at which the instability develops can be directly attributed to the magnitude of slippage. Finally, a derivation is given for the dominant wavelength of the bulges along the unstable rim.
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Affiliation(s)
- Andreas Münch
- Mathematical Institute, University of Oxford, Oxford, UK
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27
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Snoeijer JH, Eggers J. Asymptotic analysis of the dewetting rim. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:056314. [PMID: 21230583 DOI: 10.1103/physreve.82.056314] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 09/21/2010] [Indexed: 05/30/2023]
Abstract
Consider a film of viscous liquid covering a solid surface, which it does not wet. If there is an initial hole in the film, the film will retract further, forming a rim of fluid at the receding front. We calculate the shape of the rim as well as the speed of the front using lubrication theory. We employ asymptotic matching between the contact line region, the rim, and the film. Our results are consistent with simple ideas involving dynamic contact angles and permit us to calculate all free parameters of this description, previously unknown.
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Affiliation(s)
- Jacco H Snoeijer
- Physics of Fluids Group and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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28
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29
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Xu L, Sharma A, Joo SW. Substrate Heterogeneity Induced Instability and Slip in Polymer Thin Films: Dewetting on Silanized Surfaces with Variable Grafting Density. Macromolecules 2010. [DOI: 10.1021/ma1010028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lin Xu
- School of Mechanical Engineering, Yeungnam University, Gyongsan 712-749, Korea
| | - Ashutosh Sharma
- School of Mechanical Engineering, Yeungnam University, Gyongsan 712-749, Korea
- Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
| | - Sang Woo Joo
- School of Mechanical Engineering, Yeungnam University, Gyongsan 712-749, Korea
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30
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Mezger M, Sedlmeier F, Horinek D, Reichert H, Pontoni D, Dosch H. On the Origin of the Hydrophobic Water Gap: An X-ray Reflectivity and MD Simulation Study. J Am Chem Soc 2010; 132:6735-41. [DOI: 10.1021/ja910624j] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Markus Mezger
- Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany, Department of Chemical Engineering, University of California, Berkeley, California 94720, Physik Department, Technische Universität München, 85748 Garching, Germany, and European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France
| | - Felix Sedlmeier
- Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany, Department of Chemical Engineering, University of California, Berkeley, California 94720, Physik Department, Technische Universität München, 85748 Garching, Germany, and European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France
| | - Dominik Horinek
- Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany, Department of Chemical Engineering, University of California, Berkeley, California 94720, Physik Department, Technische Universität München, 85748 Garching, Germany, and European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France
| | - Harald Reichert
- Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany, Department of Chemical Engineering, University of California, Berkeley, California 94720, Physik Department, Technische Universität München, 85748 Garching, Germany, and European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France
| | - Diego Pontoni
- Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany, Department of Chemical Engineering, University of California, Berkeley, California 94720, Physik Department, Technische Universität München, 85748 Garching, Germany, and European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France
| | - Helmut Dosch
- Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany, Department of Chemical Engineering, University of California, Berkeley, California 94720, Physik Department, Technische Universität München, 85748 Garching, Germany, and European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France
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31
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Thiele U. Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:084019. [PMID: 21389395 DOI: 10.1088/0953-8984/22/8/084019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In the present contribution we review basic mathematical results for three physical systems involving self-organizing solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e. time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different systems. First, we discuss the linear stability of homogeneous steady states, i.e. flat films, and second the systematics of non-trivial steady states, i.e. drop/hole states for dewetting films and quantum-dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly unrelated physical systems mathematically, but does allow as well for discussing model extensions in a more unified way.
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Affiliation(s)
- U Thiele
- Department of Mathematical Sciences, Loughborough University, Leicestershire LE11 3TU, UK
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32
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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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33
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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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34
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Thiele U, Vancea I, Archer AJ, Robbins MJ, Frastia L, Stannard A, Pauliac-Vaujour E, Martin CP, Blunt MO, Moriarty PJ. Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:264016. [PMID: 21828464 DOI: 10.1088/0953-8984/21/26/264016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We review recent experiments on dewetting thin films of evaporating colloidal nanoparticle suspensions (nanofluids) and discuss several theoretical approaches to describe the ongoing processes including coupled transport and phase changes. These approaches range from microscopic discrete stochastic theories to mesoscopic continuous deterministic descriptions. In particular, we describe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density functional theory and (iii) a hydrodynamic thin film model. Models (i) and (ii) are employed to discuss the formation of polygonal networks, spinodal and branched structures resulting from the dewetting of an ultrathin 'postcursor film' that remains behind a mesoscopic dewetting front. We highlight, in particular, the presence of a transverse instability in the evaporative dewetting front, which results in highly branched fingering structures. The subtle interplay of decomposition in the film and contact line motion is discussed. Finally, we discuss a simple thin film model (iii) of the hydrodynamics on the mesoscale. We employ coupled evolution equations for the film thickness profile and mean particle concentration. The model is used to discuss the self-pinning and depinning of a contact line related to the 'coffee-stain' effect. In the course of the review we discuss the advantages and limitations of the different theories, as well as possible future developments and extensions.
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Affiliation(s)
- U Thiele
- Department of Mathematical Sciences, Loughborough University, Leicestershire LE11 3TU, UK
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35
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36
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Rauscher M, Blossey R, Münch A, Wagner B. Spinodal dewetting of thin films with large interfacial slip: implications from the dispersion relation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:12290-12294. [PMID: 18844382 DOI: 10.1021/la802260b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We compare the dispersion relations for spinodally dewetting thin liquid films for increasing magnitude of interfacial slip length in the lubrication limit. While the shape of the dispersion relation, in particular the position of the maximum, are equal for no-slip up to moderate-slip lengths, the position of the maximum shifts to much larger wavelengths for large slip lengths. Here, we discuss the implications of this fact for recently developed methods to assess the disjoining pressure in spinodally unstable thin films by measuring the shape of the roughness power spectrum. For polystyrene (PS) films on octadecyltrichlorosilane (OTS) covered Si wafers (with slip length b approximately 1 microm), we predict a 20% shift of the position of the maximum of the power spectrum which should be detectable in experiments.
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Affiliation(s)
- Markus Rauscher
- Max-Planck-Institut for Metallforschung, Heisenbergstrasse 3, 70569 Stuttgart, Germany.
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37
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Xu L, Shi T, An L. The dewetting dynamics of the polymer thin film by solvent annealing. J Chem Phys 2008; 129:044904. [DOI: 10.1063/1.2918734] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Moosavi A, Rauscher M, Dietrich S. Motion of nanodroplets near chemical heterogeneities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:734-742. [PMID: 18179260 DOI: 10.1021/la7017677] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We investigate the dynamics of nanoscale droplets in the vicinity of chemical steps which separate parts of a substrate with different wettabilities. Due to long-ranged dispersion forces, nanodroplets positioned on one side of the step perceive the different character of the other side even at a finite distance from the step, leading to a dynamic response. The direction of the ensuing motion of such droplets depends not only on the difference between the equilibrium contact angles on these two parts but in particular on the difference between the corresponding Hamaker constants. Therefore, the motion is not necessarily directed toward the more wettable side and can also be different from that of droplets which span the step.
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Affiliation(s)
- A Moosavi
- Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany.
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39
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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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40
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Servantie J, Müller M. Statics and dynamics of a cylindrical droplet under an external body force. J Chem Phys 2008; 128:014709. [PMID: 18190214 DOI: 10.1063/1.2813415] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J Servantie
- Institut für Theoretische Physik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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41
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42
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Khare K, Brinkmann M, Law BM, Gurevich EL, Herminghaus S, Seemann R. Dewetting of liquid filaments in wedge-shaped grooves. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:12138-12141. [PMID: 17960943 DOI: 10.1021/la701515u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The dewetting of liquid filaments in linear grooves of a triangular cross section is studied experimentally and theoretically. Homogeneous filaments of glassy polystyrene (PS) are prepared in triangular grooves in a nonequilibrium state. At elevated temperatures, the molten PS restores its material contact angle with the substrate. Liquid filaments with a convex liquid-vapor interface decay into isolated droplets with a characteristic spacing depending on the wedge geometry, wettability, and filament width. This instability is driven by the interplay of local filament width and Laplace pressure and constitutes a wide class of 1D instabilities that also include the Rayleigh-Plateau instability as a special case. Our results show an accurately exponential buildup of the instability, suggesting that fluctuations have a minor influence in our system.
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43
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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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44
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Fetzer R, Münch A, Wagner B, Rauscher M, Jacobs K. Quantifying hydrodynamic slip: a comprehensive analysis of dewetting profiles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:10559-66. [PMID: 17803324 DOI: 10.1021/la7010698] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
To characterize nontrivial boundary conditions of a liquid flowing past a solid, the slip length is commonly used as a measure. From the profile of a retracting liquid front (e.g., measured with atomic force microscopy), the slip length can be extracted with the help of a Stokes model for a thin liquid film dewetting from a solid substrate. Specifically, we use a lubrication model derived from the Stokes model for strong slippage and linearize the film profile around the flat, unperturbed film. For small slip lengths, we expand the linearized full Stokes model for small slopes up to third order. Using the respective model, we obtain, in addition to the slip length, the capillary number, from which we can estimate the viscosity of the fluid film. We compare numerical and experimental results, test the consistency and the validity of the models/approximations, and give an easy-to-follow guide of how they can be used to analyze experiments.
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Affiliation(s)
- R Fetzer
- Department of Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany.
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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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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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Münch A, Wagner B, Rauscher M, Blossey R. A thin-film model for corotational Jeffreys fluids under strong slip. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 20:365-8. [PMID: 16902756 DOI: 10.1140/epje/i2006-10031-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Accepted: 08/07/2006] [Indexed: 05/11/2023]
Abstract
We derive a thin-film model for viscoelastic liquids under strong slip which obey the stress tensor dynamics of corotational Jeffreys fluids.
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Affiliation(s)
- A Münch
- Institute of Mathematics, Humboldt University of Berlin, D-10099, Berlin, Germany
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Blossey R, Münch A, Rauscher M, Wagner B. Slip vs. viscoelasticity in dewetting thin films. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 20:267-71. [PMID: 16794776 DOI: 10.1140/epje/i2006-10018-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 06/06/2006] [Indexed: 05/10/2023]
Abstract
Ultrathin polymer films on non-wettable substrates display dynamic features which have been attributed to either viscoelastic or slip effects. Here we show that in the weak- and strong-slip regime, effects of viscoelastic relaxation are either absent or essentially indistinguishable from slip effects. Strong slip modifies the fastest unstable mode in a rupturing thin film, which questions the standard approach to reconstruct the effective interface potential from dewetting experiments.
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Affiliation(s)
- R Blossey
- Biological Nanosystems, Interdisciplinary Research Institute, c/o IEMN Avenue Poincaré, BP 60069, F-59652, Villeneuve d'Ascq, France.
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