ÉTUDE DYNAMIQUE DE POLYMÈRES SOUS CONFINEMENT QUASI-UNIAXIAL

Abstract : Thanks to numerous theoretical developments, it is now possible to draw a close relationship between polymer rheology in bulk and chain dynamics at the molecular level. Nevertheless, the peculiar properties of polymers in interfacial situations or deep confinement are not completely understood. It has been recently observed by NMR relaxometry that the confinement of polymer melts in a nanoscopic isotropic porous matrix leads to chain dynamics dramatically different from the bulk behavior: the reptation tube diameter under confinement is one order of magnitude smaller than the bulk one (for PEO: dconf = 0.6 nm << dbulk = 7 nm). This phenomenon is called "corset effect". The aim of the present work is to extend the relaxometry study reported in the literature to the case of PEO confined in an anisotropic matrix. We probe the polymer dynamics using a technique that simultaneously measures the time and space correlations: inelastic neutron scattering. The confining materials are custom-made Anodic Aluminum Oxide (AAO) membranes. The porosity of the AAO matrices is made of micrometers long macroscopically highly oriented cylindrical pores. Thanks to a concurrent small angle scattering and microscopy analysis, we show that the AAO morphology can be fully tailored by controlling the synthesis parameters. We show how to take advantage of the macroscopic orientation of AAO pores to evidence orientational dynamical effect, namely radial or longitudinal by respect to the pore, induced by the highly anisotropic pore geometry. At large scale, we observe a high anisotropic dynamics. Nevertheless, we do not observe any corset effect. From an applied point of view, the ionic conductivity of a system: PEO+Lithium salts confined in an AAO matrix decreases by an order of magnitude compared to the bulk.
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Contributor : Karine Lagrene <>
Submitted on : Monday, September 12, 2011 - 2:45:11 PM
Last modification on : Wednesday, January 23, 2019 - 2:38:11 PM
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Karine Lagrene. ÉTUDE DYNAMIQUE DE POLYMÈRES SOUS CONFINEMENT QUASI-UNIAXIAL. Analyse de données, Statistiques et Probabilités [physics.data-an]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00622540⟩

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