Laboratoire de Physique des Solides - UMR 8502

Supervisory authorities

CNRS Nom tutelle 1

Search




Home > Members > Frédéric Restagno

Frédéric Restagno

MMOI Group leader

Directeur de recherche CNRS (CNRS Research Professor)
orcid.org/0000-0001-7803-6677
Habilitation à diriger les recherches
Bât. 510 - Campus d’Orsay
91405 Orsay Cedex
France
Tél. : +33 (0)1 69 15 70 78
Fax : +33 (0)1 69 15 60 86
Mail : frederic.restagno@u-psud.fr

Orcid: orcid.org/0000-0001-7803-6677

ResearcherID: G-6460-2011
ScopudID: 55935913700
Frédéric Restagno on researchgate

Please take a look on our recent seminar at the Institut Jean le Rond d’Alembert.

My research topics- LINK

My research activity picture gallery LINK

Other activities

- Soft matter and biological physics (ex. Macroscopical physics and complexity, ex. Physique des liquides) director - Physique macroscopique et complexité
- iCFP representative for Université Paris-Saclay
- Jury de l’agrégation interne de sciences physique (2018-...)
- Jury de l’agrégation externe de sciences physique - option physique (2014-2017).
- ANR Encore Scientific coordinator
- Member of the National organization committee of the french "Olympiades de physiques"
- Nominated member of the scientific council of the Physics Department of the Université Denis Diderot.
- Nominated member of the CUFR de Physique. Université Pierre et Marie Curie.
- Nominated member of the Scientific Council Institut d’études scientifiques de Cargèse.
- Member of the Société Française de Physique, Société Française de l’Adhésion, American Adhesion Society, American Physical Society, American Chemical Society.
- Responsable du stage de formation professionnelle "Mouillage et phénomènes superficiels" - CNRS Formation. Eligible dans le cadre du DIF - [voir détails].

Research interest

- Polymer physics
- Adhesion
- Friction
- Lubrication and nanorheology
- Textured materials
- Wetting
- Antiadhesive surfaces

For more details, please visit my research page.

Science popularization

- I have been a knowledge broker in the movie "Conquerir les océans" (France 5/2P2L).
- I have participated to 9 "On n’est pas que des cobayes" (France 5/2P2L) TV shows. [watch]
- I participated to 2 stop-motion movies: "Un chercheur et son article" and "Chercheur et caféine" with C. Arène and J. Bobroff.
- I gave several seminars for broad audiences. This first one with A. Chateauminois is here or a more recent version here on friction phenomenon, this other one with E. Rio [link] is related to bubbles, drops and liquid interfaces.
- I participated to the E=M6 TV show [link]
- I briefly presented a Scientific Show : Le Lab in l’Hebdo Show (TF1).

Present PhD students

- Marina Pasquet (since oct. 2018) - Co-advised with E. Rio
- Gabriel Guyard (since oct. 2019) - Co-advised with Josh McGraw
- Tiago Outerelo-Corvo (since oct. 2020) - Co-advised with Alexis Chennevière
- Suzanne Lafon (since oct. 2020) - Co-advised with Alexis Chennevière

Former PhD students

New: Thesis available on theses.fr
- Jérôme Delacotte (co-advised with E. Rio and D. Langevin) : now assistant professor à ENS.
- Céline Cohen (co-advised with L. Léger) [webpage]
- Laurie Saulnier (co-advised with E. Rio and D. Langevin) [LinkedIn]
- Emmanuelle Martinot [LinkedIn]
- Alexis Chennevière (now researcher at the CEA - LLB laboratory)
- Lorène Champougny (co-advised with E. Rio and B. Scheid) is assistant professor at niversity Carlos III de Madrid, Getafe (UC3M)
- Laetitia Dies-Diverchy (co-advised with C. Poulard)[LinkedIn]
- Stéphanie Vuong (co-advised with L. Léger) [LinkedIn]
- Marceau Hénot (Co-advised with L. Léger). Now agrégé prépateur à l’ENS Lyon.
- M. Mantelet (2016) - Co-advised with I. Souchon and V. Mathieu at INRA
- Marion Grelzka (since sept. 2016) - Co-advised with L. Léger : now post-doc Univ. Amsterdam (D. Bonn’s group)
- Raphaelle Taub (since oct. 2017) - Co-advised with C. Poulard now MBA student.

Popular science articles

  • Lorenceau, É., Reyssat, É., Restagno, F. & Quéré, D. Pointes liquides. Reflets de la physique 15–18 (2007). doi:10.1051/refdp/2007034 [pdf]
  • Charlaix, É. et al. Propriétés hydrodynamiques au voisinage d’une surface. Reflets de la Physique 14–18 (2010). [pdf]
  • Villey, R., Cottin-Bizonne, C., Léger, L., Charlaix, É. & Restagno, F. Indenter du verre avec un liquide? Reflets de la physique 38–40 (2015). [pdf]
  • Dalnoki-Veress, K., Salez, T. & Restagno, F. Why can’t you separate interleaved books? Physics Today 69, 74–75 (2016). [pdf]
  • Restagno, F. Les empreintes digitales augmentent-elles l’adhérence ? Pour la science 389, (2010). [pdf]

Bibliography

2021



  • G. Guyard, A. Vilquin, N. Sanson, S. Jouenne, F. Restagno, and J. D. McGraw, “Near-surface rheology and hydrodynamic boundary condition of semi-dilute polymer solutions”, Soft Matter, vol. 17, no. 14, p. 3765-3774, 2021.
    Abstract: Using evanescent wave microscopy to study near-surface, semi-dilute polymer solution flows provides simultaneous access to the mechanical behaviour of the liquid and the boundary condition at the interfaces. Our results highlight the importance of electrostatic interactions between the polymers and the bounding wall. , Understanding confined flows of complex fluids requires simultaneous access to the mechanical behaviour of the liquid and the boundary condition at the interfaces. Here, we use evanescent wave microscopy to investigate near-surface flows of semi-dilute, unentangled polyacrylamide solutions. By using both neutral and anionic polymers, we show that monomer charge plays a key role in confined polymer dynamics. For solutions in contact with glass, the neutral polymers display chain-sized adsorbed layers, while a shear-rate-dependent apparent slip length is observed for anionic polymer solutions. The slip lengths measured at all concentrations collapse onto a master curve when scaled using a simple two-layer depletion model with non-Newtonian viscosity. A transition from an apparent slip boundary condition to a chain-sized adsorption layer is moreover highlighted by screening the charge with additional salt in the anionic polymer solutions. We anticipate that our study will be a starting point for more complex studies relating the polymer dynamics at interfaces to their chemical and physical composition.


  • R. Srivastava, V. Bosc, F. Restagno, C. Tournier, P. Menut, I. Souchon, and V. Mathieu, “A new biomimetic set-up to understand the role of the kinematic, mechanical, and surface characteristics of the tongue in food oral tribological studies”, Food Hydrocolloids, vol. 115, p. 106602, 2021.

2020

2019

2018

2017

2016


  • H. Alarcón, T. Salez, C. Poulard, J. - F. Bloch, É. Raphaël, K. Dalnoki-Veress, and F. Restagno, “Self-Amplification of Solid Friction in Interleaved Assemblies”, Physical review letters, vol. 116, no. 1, p. 015502, 2016.

  • A. Chenneviere, F. Cousin, F. Boue, E. Drockenmuller, K. R. Shull, L. Leger, and F. Restagno, “Direct Molecular Evidence of the Origin of Slip of Polymer Melts on Grafted Brushes”, MACROMOLECULES, vol. 49, no. 6, p. 2348-2353, 2016.
    Abstract: Neutron reflectivity has been used to investigate the effect of shear on the conformation of hydrogenated polystyrene chains end-grafted on a silicon wafer and covered by a deuterated polystyrene melt, in the grafting regime where the grafted chains at equilibrium extend in the bulk up to their radius of gyration. An experimental setup has been built to shear the samples above their glass transition temperature and then quench them rapidly after the shear. The flow-induced distorted conformation of the end-tethered chains was characterized by neutron reflectivity. We show that the effect of the shear is a decoupling between the grafted chains and the bulk chains which leads to a strong slip of the polymer melt at the solid interface.
  • K. Dalnoki-Veress, T. Salez, and F. Restagno, “Why can't you separate interleaved books?”, PHYSICS TODAY, vol. 69, no. 6, p. 74-75, 2016.

  • S. Jones, E. Rio, C. Cazeneuve, L. Nicolas-Morgantini, F. Restagno, and G. S. Luengo, “Tribological influence of a liquid meniscus in human sebum cleaning”, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, vol. 498, p. 268-275, 2016.
    Abstract: The interaction of surfactants in solution with hydrophobic materials is at the root of the process of detergency. Lipid containing micelles are formed in solution, and through water rinsing, these structures are washed out from the surface. The presence of air in the solution and the formation of foam add complexity to the system due to the increased proportion of water interfaces in contact with the surface. The latter situation is more difficult to understand. In this work, we propose, as a first step, to explore the role of the interfaces in cleaning silicon wafers previously coated with a model lipid mixture representing human sebum has been investigated. It turns out that the presence of interfaces enhances the cleaning efficiency. The effect of altering the surface properties of the silicon wafer was also investigated and it was found that changing the contact angle of the wafer brought a very strong effect on the cleaning efficiency. (C) 2016 Elsevier B.V. All rights reserved.
    Tags: Detergency, Foam-oil interaction, Surface energy.

  • Y. Zhu, A. Bironeau, F. Restagno, C. Sollogoub, and G. Miquelard-Garnier, “Kinetics of thin polymer film rupture: Model experiments for a better understanding of layer breakups in the multilayer coextrusion process”, POLYMER, vol. 90, p. 156-164, 2016.
    Abstract: We show that the kinetics of bursting of a thin film embedded in another polymer matrix can be well described by a simple equation balancing the viscous and capillary forces. The role of viscosity, interfacial tension and thickness of the layers under static conditions was investigated by adapting a simple model experiment initially designed to study the dewetting of a thin polymer film on another polymer substrate. Kinetics was correlated to instabilities occurring during multilayer coextrusion leading to the break-up of layers below a critical nanometric thickness. The results suggest that shear and elongation forces during the process actually stabilize the layers. Understanding these instabilities is of great interest since this innovative process showed potential to design at an industrial scale macromolecular materials displaying new macroscopic properties, due to interfacial and confinement effects. However, instabilities leading to the breaking of these nanometric layers will alter final properties (optical, gas barrier.). (C) 2016 Elsevier Ltd. All rights reserved.
    Tags: Dewetting, Multilayer coextrusion, Thin film.

2015



  • L. Champougny, B. Scheid, F. Restagno, J. Vermant, and E. Rio, “Surfactant-induced rigidity of interfaces: a unified approach to free and dip-coated films”, SOFT MATTER, vol. 11, no. 14, p. 2758-2770, 2015.
    Abstract: The behavior of thin liquid films is known to be strongly affected by the presence of surfactants at the interfaces. The detailed mechanism by which the latter enhance film stability is still a matter of debate, in particular concerning the influence of surface elastic effects on the hydrodynamic boundary condition at the liquid/air interfaces. In the present work, “twin” hydrodynamic models neglecting surfactant transport to the interfaces are proposed to describe the coating of films onto a solid plate (Landau-Levich-Derjaguin configuration) as well as soap film pulling (Frankel configuration). Experimental data on the entrained film thickness in both configurations can be fitted very well using a single value of the surface elasticity, which is in good agreement with independent measurements by mean of surface expansion experiments in a Langmuir through. The analysis thus shows that soap films or dip coating experiments may be used to measure the surface elasticity of surfactant solutions in the insoluble limit, namely as long as the film generation dynamics is fast compared to the surfactant adsorption timescale.
  • L. Dies, F. Restagno, R. Weil, L. Léger, and C. Poulard, “Role of adhesion between asperities in the formation of elastic solid/solid contacts”, The European Physical Journal E, vol. 38, no. 12, p. 1–8, 2015.
  • M. Dirany, L. Dies, F. Restagno, L. Leger, C. Poulard, and G. Miquelard-Garnier, “Chemical modification of PDMS surface without impacting the viscoelasticity: Model systems for a better understanding of elastomer/elastomer adhesion and friction”, Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 468, p. 174–183, 2015.
    Tags: Contact angle, Hydrosilylation, Poly(dimethylsiloxane) elastomers, Surface energy, Surface modification, Viscoelastic properties.

2014


  • L. Saulnier, L. Champougny, G. Bastien, F. Restagno, D. Langevin, and E. Rio, “A study of generation and rupture of soap films”, SOFT MATTER, vol. 10, no. 16, p. 2899-2906, 2014.
    Abstract: What are the lifetime and maximum length of a soap film pulled at a velocity V out of a bath of soapy solution? This is the question we explore in this article by performing systematic film rupture experiments. We show that the lifetime and maximal length of the films are fairly reproducible and controlled only by hydrodynamics. For surfactants with high surface elastic modulus, we argue that the rupture is triggered by the expansion of a thinning zone at the top of the film. The length l(tz) of this zone expands with time at a velocity equal to V/2, which can be obtained by a balance between gravity and viscous forces. The film lifetime is then found to decrease with the pulling velocity V, which implies that the surface tension gradient along the film increases with V. This surface tension gradient is found to be surprisingly small. Finally, the lifetime of films stabilised by solutions with small surface elastic modulus turns out to be much shorter than the ones for films with rigid interfaces.

2013


  • A. Chenneviere, E. Drockenmuller, D. Damiron, F. Cousin, F. Boue, F. Restagno, and L. Leger, “Quantitative Analysis of Interdigitation Kinetics between a Polymer Melt and a Polymer Brush”, MACROMOLECULES, vol. 46, no. 17, p. 6955-6962, 2013.
    Abstract: We present an investigation of the swelling dynamics of end-grafted hydrogenated polystyrene (h-PS) chains confined between a solid substrate and a deuterated polystyrene (d-PS) melt, based on neutron reflectometry experiments. The segment density profile of the grafted chains was measured for different annealing times. The kinetics of relaxation was quantified by measuring the amount of melt chains that have crossed the initial h-PS/d-PS sharp interface as a function of the annealing time. The dependence of this kinetics versus the molecular weight of the grafted chains, the melt chains, and the grafting density is investigated and compared to a proposed scaling model inspired from the previous work of Milner, McLeish, and O'Connor.(1,2) Moreover, the relaxation kinetics is found to highly depend on the polydispersity of the polymer brushes, and we propose a way for taking that parameter into account.

  • E. Degrandi-Contraires, A. Beaumont, F. Restagno, R. Weil, C. Poulard, and L. Leger, “Cassie-Wenzel-like transition in patterned soft elastomer adhesive contacts”, EPL, vol. 101, no. 1, 2013.
    Abstract: We present an experimental and theoretical analysis of the transition from top to mixed top and full contacts between a smooth elastomer sphere and an elastomer substrate micropatterned with hexagonal arrays of cylindrical pillars. We show that surprisingly the overall behavior of the apparent radius of contact vs. the applied load obeys JKR contact mechanics, whatever the nature of the contact (top or mixed). This allows us to propose a mechanical description predicting quantitatively the evolution of the critical load for the onset of full contact with the pattern geometry and qualitatively that of the area of full contact above this threshold. We emphasize the role of the mechanical coupling between the pillars induced by the deformation of the substrate for large enough densities of pillars. Copyright (C) EPLA, 2013

  • R. Villey, E. Martinot, C. Cottin-Bizonne, M. Phaner-Goutorbe, L. Leger, F. Restagno, and E. Charlaix, “Effect of Surface Elasticity on the Rheology of Nanometric Liquids”, PHYSICAL REVIEW LETTERS, vol. 111, no. 21, 2013.
    Abstract: The rheological properties of liquids confined to nanometer scales are important in many physical situations. In this Letter, we demonstrate that the long-range elastic deformation of the confining surfaces must be taken into account when considering the rheology of nanometric liquids. In the case of a squeeze-flow geometry, we show that below a critical distance D-c, the liquid is clamped by its viscosity and its intrinsic properties cannot be disentangled from the global system response. Using nanorheology experiments, we demonstrate that picometer elastic deflections of the rigid confining surfaces dominate the overall mechanical response of nanometric liquids confined between solid walls.

2012


  • T. Barraud, F. Restagno, S. Devisme, C. Creton, and L. Leger, “Formation of diblock copolymers at PP/PA(6) interfaces and their role in local crystalline organization under fast heating and cooling conditions”, POLYMER, vol. 53, no. 22, p. 5138-5145, 2012.
    Abstract: Multilayer polypropylene/polyamide 6 (PP/PA(6)) films are commonly obtained by co-extrusion, with PP/PA(6) interfaces reinforced through diblock PP/PA(6) copolymers formed in situ by the reaction of maleic anhydride modified PP on the NH2 end-groups of PA(6) molecules at the contact between the two molten polymers. We present procedures allowing one to form PP/PA(6) thin films assemblies in thermal conditions (fast heating and cooling kinetics, short annealing times) representative of typical co-extrusion conditions. Selective dissolution of the PA(6) part of the assemblies permits to first dose the surface density of copolymer, and second to analyze by AFM imaging the incidence of the copolymer surface density on the crystalline morphology at the interface. These experiments are a first step toward the identification of the key parameters controlling the fracture toughness in these multilayer films. (C) 2012 Elsevier Ltd. All rights reserved.
    Tags: AFM, Coextrusion, Copolymer.

  • C. Cohen, D. Damiron, S. Ben Dkhil, E. Drockenmuller, F. Restagno, and L. Leger, “Synthesis of well-defined poly(dimethylsiloxane) telechelics having nitrobenzoxadiazole fluorescent chain-ends via thiol-ene coupling”, JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY, vol. 50, no. 9, p. 1827-1833, 2012.
    Abstract: Well-defined PDMS telechelics having nitrobenzoxadiazole (NBD) fluorescent probes covalently attached at both chain-ends were prepared in two steps and a series of fractionation procedures starting from commercially available divinyl-terminated PDMS having a broad molar mass dispersity. First, thiol-ene coupling between 6-mercapto-1-hexanol and vinyl chain-ends allowed the formation of dihydroxy-terminated PDMS telechelics through the formation of a thioether linkage. The resulting material was then sequentially fractionated using dichloromethane/methanol mixtures to afford several well-defined dihydroxy-terminated PDMS fractions having sharp distributions of molar masses (Mn = 99.5158 kDa and D < 1.2). The NBD fluorescent probes were then attached at both chain-ends by N,N'-dicyclohexylcarbodiimide/4-(dimethylamino)pyridine esterification coupling between the hydroxyl groups and 6-(7-nitrobenzofurazan-4-ylamino)hexanoic acid. The resulting fluorescent PDMS telechelics were characterized by SEC, 1H NMR, UVvisible, and fluorescence spectroscopies. These materials are suitable probes to investigate the dynamics of polymer chains in bulk or at interfaces by the fringe pattern fluorescent recovery after photobleaching technique. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
    Tags: esterification, fluorescence, functionalization of polymers, NBD, nitrobenzoxadiazole, PDMS, polysiloxanes, silicones, telechelics, thiol-ene coupling, UV-vis spectroscopy.
  • E. Degrandi-Contraires, C. Poulard, F. Restagno, and L. Léger, “Sliding friction at soft micropatterned elastomer interfaces”, Faraday discussions, vol. 156, no. 1, p. 255–265, 2012.

  • J. Delacotte, L. Montel, F. Restagno, B. Scheid, B. Dollet, H. A. Stone, D. Langevin, and E. Rio, “Plate Coating: Influence of Concentrated Surfactants on the Film Thickness”, LANGMUIR, vol. 28, no. 8, p. 3821-3830, 2012.
    Abstract: We present a large range of experimental data concerning the influence of surfactants on the well-known Landau-Levich-Derjaguin experiment where a liquid film is generated by pulling a plate out of a bath. The thickness h of the film was measured as a function of the pulling velocity V for different kinds of surfactants (C12E6, which is a nonionic surfactant, and DeTAB and DTAB, which are ionic) and at various concentrations near and above the critical micellar concentration (cmc). We report the thickening factor alpha = h/h(LLD), where h(LLD) is the film thickness obtained without a surfactant effect, i.e., as for a pure fluid but with the same viscosity and surface tension as the surfactant solution, over a wide range of capillary numbers (Ca = eta V/gamma, with eta being the surfactant solution viscosity and gamma its surface tension) and identify three regimes: (i) at small Ca alpha is large due to confinement and surface elasticity (or Marangoni) effects, (ii) for increasing Ca there is an intermediate regime where alpha decreases as Ca increases, and (iii) at larger (but still small) Ca alpha is slightly higher than unity due to surface viscosity effects. In the case of nonionic surfactants, the second regime begins at a fixed Ca, independent of the surfactant concentration, while for ionic surfactants the transition depends on the concentration, which we suggest is probably due to the existence of an electrostatic barrier to surface adsorption. Control of the physical chemistry at the interface allowed us to elucidate the nature of the three regimes in terms of surface rheological properties.

  • S. Leroy, A. Steinberger, C. Cottin-Bizonne, F. Restagno, L. Leger, and E. Charlaix, “Hydrodynamic Interaction between a Spherical Particle and an Elastic Surface: A Gentle Probe for Soft Thin Films”, PHYSICAL REVIEW LETTERS, vol. 108, no. 26, 2012.
    Abstract: We study the hydrodynamic interaction between a sphere and an elastic surface at a nanoscale with a dynamic surface force apparatus. We show that the interplay between viscous forces and elastic deformations leads to very rich scaling properties of the force response, providing a unique signature of the surface elastic behavior. These properties are illustrated on three different examples: a thick elastomer, a thin elastomer film, and a layer of micrometric bubbles. We show that this fluid probing allows one to measure the Young's modulus of surfaces and soft thin layers at distance, without any direct solid-solid contact.

2011

  • C. Cohen, F. Restagno, C. Poulard, and L. Léger, “Incidence of the molecular organization on friction at soft polymer interfaces”, Soft Matter, vol. 7, no. 18, p. 8535–8541, 2011.

  • M. Maleki, M. Reyssat, F. Restagno, D. Quere, and C. Clanet, “Landau-Levich menisci”, JOURNAL OF COLLOID AND INTERFACE SCIENCE, vol. 354, no. 1, p. 359-363, 2011.
    Abstract: As shown by Landau, Levich and Derjaguin, a plate withdrawn out of a wetting bath at low capillary numbers deforms the very top of the liquid reservoir. At this place, a dynamic meniscus forms, whose shape and curvature select the thickness of the film entrained by the plate. In this paper, we measure accurately the thickness of the entrained film by reflectometry, and characterize the dynamic meniscus, which is found to decay exponentially towards the film. We show how this shape is modified when reversing the motion: as a plate penetrates the bath, the dynamic meniscus can “buckle” and present a stationary wavy profile, which we discuss. (C) 2010 Elsevier Inc. All rights reserved.
    Tags: Dip coating, Dynamic meniscus, Lubrication, Wavy film, wetting.

  • C. Poulard, F. Restagno, R. Weil, and L. Léger, “Mechanical tuning of adhesion through micro-patterning of elastic surfaces”, Soft matter, vol. 7, no. 6, p. 2543–2551, 2011.

  • L. Saulnier, F. Restagno, J. Delacotte, D. Langevin, and E. Rio, “What Is the Mechanism of Soap Film Entrainment?”, LANGMUIR, vol. 27, no. 22, p. 13406-13409, 2011.
    Abstract: Classical Frankel's law describes the formation of soap films and their evolution upon pulling, a model situation of film dynamics in foams (formation, rheology, and destabilization). With the purpose of relating film pulling to foam dynamics, we have built a new setup able to give an instantaneous measurement of film thickness, thus allowing us to determine film thickness profile during pulling. We found that only the lower part of the film is of uniform thickness and follows Frankel's law, provided the entrainment velocity is small. We show that this is due to confinement effects: there is not enough surfactant in the bulk to fully cover the newly created surfaces which results in immobile film surfaces. At large velocities, surfaces become mobile and then Frankel's law breaks down, leading to a faster drainage and thus to a nonstationary thickness at the bottom of the film. These findings should help in understanding the large dispersion of previous experimental data reported during the last 40 years and clarifying the pulling phenomenon of thin liquid films.

2010

  • C. Cohen, F. Restagno, C. Poulard, and L. Léger, “Wetting and dewetting transition: an efficient toolbox for characterizing low-energy surfaces”, Langmuir, vol. 26, no. 19, p. 15345–15349, 2010.

  • J. Delacotte, E. Rio, F. Restagno, C. Uzuem, R. von Klitzing, and D. Langevin, “Viscosity of Polyelectrolytes Solutions in Nanofilms”, LANGMUIR, vol. 26, no. 11, p. 7819-7823, 2010.
    Abstract: We use a thin film pressure balance to probe the rheological properties of thin liquid films. These films are made from mixed aqueous solutions of surfactants and polyelectrolytes. They drain under applied pressure in a noncontinuous way due to a stratification process of the polyelectrolytes network. The stratification kinetics was studied for films stabilized by different surfactants. Using a theoretical model, it is possible to examine the effect of both the surfactant and the film thickness on the local dissipation. On one hand, it was observed that dissipation depends on the polyelectrolyte concentration only, regardless whether the surfactant is neutral or bears electric charges opposite to those of the polyelectrolyte. On the other hand, it was found that dissipation is stronger in thinner films.

  • B. Scheid, J. Delacotte, B. Dollet, E. Rio, F. Restagno, E. A. van Nierop, I. Cantat, D. Langevin, and H. A. Stone, “The role of surface rheology in liquid film formation”, EPL, vol. 90, no. 2, 2010.
    Abstract: The role of surface rheology in fundamental fluid dynamical systems, such as liquid coating flows and soap film formation, is poorly understood. We investigate the role of surface viscosity in the classical film-coating problem. We propose a theoretical model that predicts film thickening based on a purely surface-viscous theory. The theory is supported by a set of new experimental data that demonstrates slight thickening even at very high surfactant concentrations for which Marangoni effects are irrelevant. The model and experiments represent a new regime that has not been identified before. Copyright (C) EPLA, 2010

2009


  • S. Leroy, F. Restagno, and E. Charlaix, “Fine calibration of the residual dissipation in a surface forces apparatus using a capacitive sensor”, REVIEW OF SCIENTIFIC INSTRUMENTS, vol. 80, no. 8, 2009.
    Abstract: The design of a dynamic surface force apparatus using a capacitive sensor has been useful in the past to study the nanorheological behavior of thin liquid films confined between a sphere and a plane. This allows a precise measurement of the hydrodynamical boundary condition of liquids down to some molecular sizes. However for thick liquid films, the viscous force is decreased and the dissipation due to the flow of air in the capacitive sensor becomes of the same order of magnitude than the force due to the liquid flow. In the present paper we present an original technique to characterize this residual force due to the capacitive sensor and we show that a precise subtraction of this force extends the precision of the device to the case of thick liquid films of low viscosity. This correction should be of major importance to extend the capability of surface forces apparatus to measure very large boundary slippage of simple liquids. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3187223]
  • F. Restagno, C. Poulard, C. Cohen, L. Vagharchakian, and L. Léger, “Contact angle and contact angle hysteresis measurements using the capillary bridge technique”, Langmuir, vol. 25, no. 18, p. 11188–11196, 2009.

  • L. Vagharchakian, F. Restagno, and L. Leger, “Capillary Bridge Formation and Breakage: A Test to Characterize Antiadhesive Surfaces”, JOURNAL OF PHYSICAL CHEMISTRY B, vol. 113, no. 12, p. 3769-3775, 2009.
    Abstract: In order to characterize very weak adhesive surfaces, we have developed a quantitative test inspired by the Johnson, Kendall, and Roberts adhesion test for soft adhesives, which relies on the formation and then the rupture of a capillary bridge between the surface to be tested and a liquid bath. Both the shape and the kinetics of breakage of the capillary bridge for various coatings put into contact with liquids of various viscosities and surface tensions have been studied. Several pull off regimes can be distinguished. For low pull off velocities, a quasi-static regime is observed, well described by capillary equations and sensitive to the hysteresis of the contact angle of the fluid on the coating. Above a critical pull off velocity that depends on the fluid viscosity, a dynamic regime is observed, characterized by the formation of a flat pancake of fluid on the coating that recedes more slowly than the capillary bridge itself. After the breakage of the capillary bridge, a small drop can remain attached to the surface. The volume of this drop depends on the dynamical regime and is strongly affected by very small differences between the coatings. The aptitude of this test in characterizing very weakly adhesive surfaces is exemplified by a comparison between three different perfluorinated coatings.

2007


  • N. Amouroux, F. Restagno, and L. Leger, “Adhesion at poly(butylacrylate)-poly(dimethylsiloxane) interfaces”, JOURNAL OF ADHESION, vol. 83, no. 8, p. 741-760, 2007.
    Abstract: We present an investigation of the adhesion modulation mechanisms of silica-like nanoparticles (MQ resins) incorporated in polydimethylsiloxane ( PDMS) elastomers and acrylic adhesives. The Johnson-Kendall-Roberts (JKR) test has been used to gain information on the both zero velocity and the velocity dependence of the adhesive strength, avoiding as much as possible contributions to the adhesive strength of bulk dissipation in the adhesive ( which is not the case with peel tests). As the incorporation of the MQ resins into the elastomers deeply affects their own mechanical properties, the loading and unloading curves of small poly(butylacrylate) (PBA) lenses on either PDMS elastomers, adsorbed PDMS and pure MQ resin layers are compared in a systematic manner. The PBA chains are observed to have a neat affinity for the MQ resin nanoparticles. When MQ resins are present at the interface, they tend to prevent facture propagation, thus producing a larger deformation of the PBA lens. The modulation of adhesion is then dominated by the corresponding dissipation inside the acrylic adhesive.
    Tags: acrylic adhesives, adhesion mechanisms, dissipation, interfacial interactions, JKR test, modulation of adhesion, silicone elastomers.

2004


  • C. Colin, C. R. Pasquier, P. Auban-Senzier, F. Restagno, S. Baudron, P. Batail, and J. Fraxedas, “Transport properties of monocrystalline microwires of EDT-TTF(CONHMe)(2) and (TMTSF)(2)ClO4”, SYNTHETIC METALS, vol. 146, no. 3, p. 273-277, 2004.
    Abstract: The monomolecular compound ethylenedithiotetrathiafulvalene (EDT-TTF(CONHMe)(2)) and the charge transfer salt tetramethyltetraselenafulvalene (TMTSF)(2)ClO4 were successfully recrystallized using the drop casting method. Samples of various sizes were obtained, with widths as small as 300 nm and thicknesses above 30 nm. The length of the samples can reach I mm. The conductivity of the former compound, sigmaapproximate to3.10(-7) S cm(-1) is typical of neutral TTF derivatives. Its bulk mobility is about mu(b)approximate to1 cm(2)/Vs. For the thinnest samples of (TMTSF)(2)ClO4, the two point conductivity is dominated by the sample conductivity instead of the contact resistance. (C) 2004 Elsevier B.V. All rights reserved.
    Tags: drop casting, electrical conductivity, microwires, organic compound, tetrathiafulvalene.

  • F. Restagno, L. Bocquet, and E. Charlaix, “Where does a cohesive granular heap break?”, EUROPEAN PHYSICAL JOURNAL E, vol. 14, no. 2, p. 177-183, 2004.
    Abstract: In this paper, we consider the effect of cohesion on the stability of a granular heap and compute the maximum angle of stability of the heap as a function of the cohesion. We show that the stability is strongly affected by the dependence of the cohesion on the local pressure. In particular, this dependence is found to determine the localization of the failure plane. While for a constant adhesion force, slip occurs deep inside the heap, surface failure is obtained for a linear variation of the cohesion on the normal stress. Such a transition allows to interpret some recent experimental results on cohesive materials.

--- Export the selection using the format