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Rôle des interfaces et du confinement dans les films liquides minces

Abstract : Interfaces properties and confinement effects of complex fluids are involved in stabilization of foams. This question is also related to micro-fluidics and nano-fluidics, which have been developed during recent years. Mixed solutions made of polyelectrolytes and surfactants have been used to study the influence of both confinement and surfactant in ultra-thin films (< 100 nm). Dissipation in these films was probed by using a thin film pressure balance as a rheometer and an hydrodynamics model. An effective viscosity can be extracted, which is higher for thinner films and affected by the nature of the surfactant. Generation of thicker films (a few microns) by dip coating of a solid plate enables to rule out the confinement. Several surfactants with different solubilities were used. A dynamic transition of thickening was found out and quantitatively explained. Furthermore, in the frame of a collaboration, an hydrodynamic model was developed to take into account surface viscosity in the thickening phenomenon. We could characterize the regime in which interfacial rheology is driven by pure surface viscosity. This model could be the first step toward a model taking into account both surface elasticity and surface viscosity.
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https://tel.archives-ouvertes.fr/tel-02374614
Contributor : Jerome Delacotte <>
Submitted on : Thursday, November 21, 2019 - 3:41:28 PM
Last modification on : Friday, March 27, 2020 - 3:41:16 AM

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  • HAL Id : tel-02374614, version 1

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Jérôme Delacotte. Rôle des interfaces et du confinement dans les films liquides minces. Matière Molle [cond-mat.soft]. Université Paris 7, 2009. Français. ⟨tel-02374614⟩

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