Laboratoire de Physique des Solides - UMR 8502

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  • 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.

  • S. Costa, S. Cohen-Addad, A. Salonen, and R. Höhler, “The dissipative rheology of bubble monolayers”, Soft Matter, vol. 9, no. 3, p. 886-895, 2013.

  • 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

  • É. Degrandi-Contraires, A. Beaumont, F. Restagno, R. Weil, C. Poulard, and L. Léger, “Cassie-Wenzel–like transition in patterned soft elastomer adhesive contacts”, EPL (Europhysics Letters), vol. 101, no. 1, p. 14001, 2013.

  • S. Heitkam, Y. Yoshitake, F. Toquet, D. Langevin, and A. Salonen, “Speeding up of Sedimentation under Confinement”, Physical Review Letters, vol. 110, no. 17, Apr. 2013.

  • A. Maestro, W. Drenckhan, E. Rio, and R. Höhler, “Liquid dispersions under gravity: volume fraction profile and osmotic pressure”, Soft Matter, vol. 9, no. 8, p. 2531, 2013.
    Abstract: Many physical properties of concentrated dispersions of immiscible fluids are captured by the concept of an osmotic pressure, which measures how much energy is required to deform the bubbles or drops upon compaction. This pressure has a strong impact on the flow and drainage behavior of dispersions. Nevertheless, theoretical models describing its variation with the volume fraction phi of the continuous phase are so far available only in the limits of low or high phi and experimental data are scarce. We report an experimental study of osmotic pressure in foams and emulsions, showing how the effects of phi, disorder, grain size, polydispersity and interfacial tension can all be captured by a single law which satisfies previously established theoretical constraints. Building on this result, we propose the first equation which accurately describes the variation of the volume fraction with the height of a fluid dispersion under gravity.
  • M. Trejo, C. Douarche, V. Bailleux, C. Poulard, S. Mariot, C. Regeard, and E. Raspaud, “Elasticity and wrinkled morphology of Bacillus subtilis pellicles”, Proceedings of the National Academy of Sciences, vol. 110, no. 6, p. 2011–2016, 2013.

  • G. Tresset, C. Marculescu, A. Salonen, M. Ni, and C. Iliescu, “Fine Control Over the Size of Surfactant–Polyelectrolyte Nanoparticles by Hydrodynamic Flow Focusing”, Analytical Chemistry, vol. 85, no. 12, p. 5850-5856, Jun. 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.


  • L. R. Arriaga, W. Drenckhan, A. Salonen, J. A. Rodrigues, R. Íñiguez-Palomares, E. Rio, and D. Langevin, “On the long-term stability of foams stabilised by mixtures of nano-particles and oppositely charged short chain surfactants”, Soft Matter, vol. 8, no. 43, p. 11085, 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.

  • F. Boulogne, L. Pauchard, and F. Giorgiutti-Dauphiné, “Instability and morphology of polymer solutions coating a fibre”, Journal of Fluid Mechanics, vol. 704, p. 232–250, 2012.
    Abstract: We report an experimental study on the dynamics of a thin film of polymer solution coating a vertical fiber. The liquid film has first a constant thickness and then undergoes the Rayleigh-Plateau instability which leads to the formation of sequences of drops, separated by a thin film, moving down at a constant velocity. Different polymer solutions are used, i.e. xanthan solutions and polyacrylamide (PAAm) solutions. These solutions both exhibit shear-rate dependence of the viscosity, but for PAAm solutions, there are strong normal stresses in addition of the shear-thinning effect. We characterize experimentally and separately the effects of these two non-Newtonian properties on the flow on the fiber. Thus, in the flat film observed before the emergence of the drops, only shear-thinning effect plays a role and tends to thin the film compared to the Newtonian case. The effect of the non-Newtonian rheology on the Rayleigh-Plateau instability is then investigated through the measurements of the growth rate and the wavelength of the instability. Results are in good agreement with linear stability analysis for a shear-thinning fluid. The effect of normal stress can be taken into account by considering an effective surface tension which tends to decrease the growth rate of the instability. Finally, the dependence of the morphology of the drops with the normal stress is investigated and a simplified model including the normal stress within the lubrication approximation provides good quantitative results on the shape of the drops.
    Tags: Rayleigh-Plateau.

  • F. Boulogne, L. Pauchard, and F. Giorgiutti-Dauphiné, “Effect of a non-volatile cosolvent on crack patterns induced by desiccation of a colloidal gel”, Soft Matter, vol. 8, no. 32, p. 8505–8510, 2012.
    Abstract: The consolidation of colloidal gels results in enormous stresses that are usually released by the formation of undesirable cracks. The capacity of a gel network to crack during drying depends on the existence and significance of a pressure gradient in the pore liquid; in addition it depends on the way the gel relaxes the resulting drying stresses. In this paper the effect of a binary mixture of solvents saturating the gel network on the crack patterns formation is investigated. Indeed, incorporation of a small quantity of non-volatile cosolvent, i.e. glycerol, inhibits drying-induced cracks; moreover addition of a concentration greater than 10% to a colloidal dispersion leads to a crack free coating under room conditions. Mass variation with time reveals that both evaporation rate and cracking time are not affected by glycerol, in the range of added glycerol contents studied. In addition measurements of mechanical properties show that the elastic modulus is reduced with glycerol content. The decrease of the number of cracks with the glycerol content is related to the flattening of the pressure gradient in the pore liquid. The mechanism is shown to be due to the combination of two processes: flow driven by the pressure gradient and diffusion mechanisms in accordance with Scherer's work (1989).
    Tags: cracks.

  • 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.
  • L. Dominique and E. Rio, “Coalescence in Foams and Emulsions”, in Encyclopedia of surface and colloid sciences, Taylor & Francis, 2012.

  • 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.

  • F. Muller, J. Degrouard, J. Jestin, A. Brûlet, and A. Salonen, “How clay colloids surround internally self-assembled phytantriol drops.”, Soft Matter, vol. 8, no. 40, p. 10502, 2012.
  • B. Scheid, S. Dorbolo, L. R. Arriaga, and E. Rio, “Antibubble dynamics: The drainage of an air film with viscous interfaces”, Physical Review Letters, vol. 109, no. 26, 2012.
    Abstract: An antibubble is a spherical air film that is immersed in a surfactant mixture and drains under the action of hydrostatic pressure. A dynamical model of this film is proposed that accounts for the surface shear viscosity effects in the case of purely viscous interfaces, which applies for surfactants whose adsorption rate is much larger than advection rate and at a concentration much above the critical micelle concentration. Our model shows that the lifetime of the antibubbles in this case increases with surface shear viscosity, denoted ϵ, whose value is measured independently, all in agreement with experimental measurements. We also found that the critical thickness, hc, at film rupture due to van der Waals interactions slightly depends on the surface shear viscosity, namely hc∝ϵ1/6.

  • F. Schüler, D. Schamel, A. Salonen, W. Drenckhan, M. D. Gilchrist, and C. Stubenrauch, “Synthesis of Macroporous Polystyrene by the Polymerization of Foamed Emulsions”, Angewandte Chemie International Edition, vol. 51, no. 9, p. 2213-2217, Feb. 2012.

  • A. Testouri, L. R. Arriaga, C. Honorez, M. Ranft, J. Rodrigues, A. V. D. Net, A. Lecchi, A. Salonen, E. Rio, R. Guillermic, D. Langevin, and W. Drenckhan, “Generation of porous solids with well-controlled morphologies by combining foaming and flow chemistry on a Lab-on-a-Chip”, Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 413, p. 17–24, 2012.

  • H. Yunfei, S. Yazhuo, L. Honglai, L. Dominique, and S. Anniina, “Surfactant Adsorption onto Interfaces: Measuring the Surface Excess in Time”, Langmuir, vol. 28, no. 6, p. 3146-3151, Feb. 2012.


  • F. Boulogne and S. J. Cox, “Elastoplastic flow of a foam around an obstacle”, Phys. Rev. E, vol. 83, no. 4, p. 041404, 2011.
    Abstract: We simulate quasistatic flows of an ideal two-dimensional monodisperse foam around different obstacles, both symmetric and asymmetric, in a channel. We record both pressure and network contributions to the drag and lift forces, and study them as a function of obstacle geometry. We show that the drag force increases linearly with the cross section of an obstacles. The lift on an asymmetric aerofoil-like shape is negative and increases with its arc length, mainly due to the pressure contribution.
    Tags: foams.

  • F. Brau, H. Vandeparre, A. Sabbah, C. Poulard, A. Boudaoud, and P. Damman, “Multiple-length-scale elastic instability mimics parametric resonance of nonlinear oscillators”, Nature Physics, vol. 7, no. 1, p. 56–60, 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.

  • Y. Desfougères, A. Saint-Jalmes, A. Salonen, V. Vié, S. Beaufils, S. Pezennec, B. Desbat, V. Lechevalier, and F. Nau, “Strong Improvement of Interfacial Properties Can Result from Slight Structural Modifications of Proteins: The Case of Native and Dry-Heated Lysozyme”, Langmuir, vol. 27, no. 24, p. 14947-14957, Dec. 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.

  • J. A. Rodrigues, E. Rio, J. Bobroff, D. Langevin, and W. Drenckhan, “Colloids and Surfaces A : Physicochemical and Engineering Aspects Generation and manipulation of bubbles and foams stabilised by magnetic nanoparticles”, Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 384, no. 1-3, p. 408–416, 2011.

  • A. Salonen, R. Lhermerout, E. Rio, D. Langevin, and A. Saint-Jalmes, “Dual gas and oil dispersions in water: production and stability of foamulsion”, Soft Matter, 2011.
    Abstract: In this study we have investigated mixtures of oil droplets and gas bubbles and show that the oil can have two very different roles, either suppressing foaming or stabilising the foam. We have foamed emulsions made from two different oils (rapeseed and dodecane). For both oils the requirement for the creation of foamulsions is the presence of surfactant above a certain critical threshold, independent of the concentration of oil present. Although the foamability is comparable, the stability of the foamed emulsions is very different for the two oils studied. Varying a few simple parameters gives access to a wide range of behaviours, indeed three different stability regimes are observed: a regime with rapid collapse (within a few minutes), a regime where the oil has no impact, and a regime of high stability. This last regime occurs at high oil fraction in the emulsion, and the strong slowing down of ageing processes is due to the confinement of packed oil droplets between bubbles. We thus show that a simple system consisting of surfactant, water, oil and gas is very versatile and can be controlled by choosing the appropriate physical chemical parameters.
    Attachment Version soumise 714.9 kb (source)
    Attachment Version soumise 714.9 kb (source)

  • 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.

  • A. Stocco, E. Rio, B. P. Binks, and D. Langevin, “Aqueous foams stabilized solely by particles”, vol. 7, no. 4, p. 1260–1267, 2011.

  • N. Vandewalle, H. Caps, G. Delon, A. Saint-Jalmes, E. Rio, L. Saulnier, M. Adler, A. L. Biance, O. Pitois, and S. C. Addad, “Foam stability in microgravity”, in Journal of Physics: Conference Series, 2011, vol. 327, p. 12024.

  • D. Varade, D. Carriere, L. R. Arriaga, A. L. Fameau, E. Rio, D. Langevin, and W. Drenckhan, “On the origin of the stability of foams made from catanionic surfactant mixtures”, Soft Matter, vol. 7, no. 14, p. 6557–6570, 2011.
    Abstract: Using mixtures of the anionic myristic acid (C13COOH) and the cationic cetyl trimethylammonium chloride (C16TA+Cl-) in aqueous solutions at a 2 : 1 ratio, we show that the outstanding stability of foams generated from sufficiently concentrated "catanionic" surfactant mixtures can be explained by a synergy effect between two fundamentally different mechanisms. Applying a multi-scale approach, in which we link static and dynamic properties of the bulk solutions, isolated gas/liquid interfaces, thin liquid films and foams, we identify these two mechanisms to be as follows: firstly, cationic mixtures create tightly packed surfactant layers at gas/liquid interfaces, which are strongly viscoelastic and also confer high disjoining pressures when two interfaces are approaching each other to form a thin liquid film. Foams created with such kind of interfaces tend to be extremely stable against coalescence (film rupture) and coarsening (gas exchange). However, typical time scales to cover the interfaces are much longer than typical foaming times. This is why a second mechanism plays a key role, which is due to the presence of micron-sized catanionic vesicles in the foaming solution. The bilayers of these vesicles are in a gel-like state, therefore leading to nearly indestructible objects which act like elastic micro-spheres. At sufficiently high concentrations, these vesicles jam in the presence of the confinement between bubbles, slowing down the drainage of liquid during the initial foaming process and therefore providing time for the interfaces to be covered. Furthermore, the tightly packed vesicles strongly reduce bubble coalescence and gas transfer between bubbles.
  • B. M. Weon, J. H. Je, and C. Poulard, “Convection-enhanced water evaporation”, AIP Advances, vol. 1, no. 1, p. 012102, 2011.

  • D. Y. Zang, E. Rio, G. Delon, B. Wei, and D. Langevin, “Influence of the contact angle of silica nanoparticles at the air–water interface on the mechanical properties of the layers composed of these particles”, Molecular Physics, vol. 109, p. 7–10, 2011.
    Tags: Contact angle, foams, nanoparticle monolayers, surface rheology.


  • 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.

  • F. Muller, A. Salonen, and O. Glatter, “Phase behavior of Phytantriol/water bicontinuous cubic Pn3m cubosomes stabilized by Laponite disc-like particles”, Journal of Colloid and Interface Science, vol. 342, no. 2, p. 392-398, 2010.

  • R. - V. Ostaci, D. Damiron, Y. Grohens, L. Leger, and E. Drockenmuller, “Click Chemistry Grafting of Poly(ethylene glycol) Brushes to Alkyne-Functionalized Pseudobrushes”, LANGMUIR, vol. 26, no. 2, p. 1304-1310, Jan. 2010.

  • 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

  • D. Zang, E. Rio, D. Langevin, B. Wei, and B. Binks, “Viscoelastic properties of silica nanoparticle monolayers at the air-water interface”, The European Physical Journal E: Soft Matter and Biological Physics, vol. 31, no. 2, p. 125–134, 2010.


  • R. M. Guillermic, A. Salonen, J. Emile, and A. Saint-Jalmes, “Surfactant foams doped with laponite: unusual behaviors induced by aging and confinement”, Soft Matter, vol. 5, no. 24, p. 4975, 2009.

  • K. \a are H. Jensen, E. Rio, R. Hansen, C. Clanet, and T. Bohr, “Osmotically driven pipe flows and their relation to sugar transport in plants”, Journal of Fluid Mechanics, vol. 636, p. 371–396, 2009.
    Abstract: In plants, osmotically driven flows are believed to be responsible for translocation of sugar in the pipe-like phloem cell network, spanning the entire length of the plant – the so-called Münch mechanism. In this paper, we present an experimental and theoretical study of transient osmotically driven flows through pipes with semi-permeable walls. Our aim is to understand the dynamics and structure of a ‘sugar front', i.e. the transport and decay of a sudden loading of sugar in a water-filled pipe which is closed in both ends. In the limit of low axial resistance (valid in our experiments as well as in many cases in plants) we show that the equations of motion for the sugar concentration and the water velocity can be solved exactly by the method of characteristics, yielding the entire flow and concentration profile along the tube. The concentration front decays exponentially in agreement with the results of Eschrich, Evert & Young (Planta (Berl.), vol. 107, 1972, p. 279). In the opposite case of very narrow channels, we obtain an asymptotic solution for intermediate times showing a decay of the front velocity as M−1/3t−2/3 with time t and dimensionless number M ηκL2r−3 for tubes of length L, radius r, permeability κ and fluid viscosity η. The experiments (which are in the small M regime) are in good quantitative agreement with the theory. The applicability of our results to plants is discussed and it is shown that it is probable that the Münch mechanism can account only for the short distance transport of sugar in plants.

  • 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.

  • A. Stocco, W. Drenckhan, E. Rio, D. Langevin, and B. P. Binks, “Particle-stabilised foams: an interfacial study”, Soft Matter, vol. 5, no. 11, p. 2215–2222, 2009.
    Abstract: In an attempt to elucidate the remarkable stability of foams generated from dispersions of partially hydrophobic nanoparticles (fumed silica), we present investigations into the static and dilational properties of the gas-liquid interfaces of such dispersions. By relating the dynamic surface tension [gamma](t) and the dilational elasticity E measured using an oscillating bubble device, we confirm that the Gibbs stability criterion E \textgreater [gamma]/2 against foam coarsening is fulfilled. We complement these studies using ellipsometry and Brewster angle microscopy, which provide evidence for a pronounced adsorption barrier for the particles and a network-like structure in the interface at sufficiently high concentrations. We observe this structure also in freely suspended films drawn from the same particle dispersions.
    Note Note

  • 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.


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