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Caractérisation structurale, poreuse et mécanique de films minces de silice mésoporeuse.
Influence de la fonctionnalisation

Abstract : This work dealt with the synthesis and characterization of mesoporous silica thin films. The synthesis uses the surfactant self-assembly route in order to template a silica gel. Hybrid thin films presenting a high degree of organization at the nanometer scale are obtained. Then the surfactant removal leads to materials of organized and tailored porosities and of large surface areas.
Different synthesis parameters have been investigated. In situ measurements carried out by X ray Reflectivity (XR) and Grazing Incidence Small Angle X-ray Scattering (GISAXS) have evidenced the major role played by the relative humidity. Some surfactant removal methods by ethanol rinsing have also been tested, with the intent to empty the mesopores without collapsing the mesostructured films.
Based on the complete analysis of the reflectivity curves, a new method to determine the porosity of thin films has been developed. In combination with GISAXS experiments the pore and wall sizes, the surface area of the films and their pore distortion were obtained.
The mesopores have a perfect size to promote the capillary condensation of water at ambient relative humidity. As the electron density contrast decreases strongly when water infiltrates the mesopores, the XR and GISAXS techniques have permitted to monitor by different ways the adsorption and the desorption of water in the porous network. The pore size distribution and porosity were estimated from the analysis of isotherms. Looking at the direct film structure deformation during the humidity cycles, some mechanical properties have also been investigated yielding the quantitative determination of the Young Modulus.
Finally, this thesis was concluded by the study of the mesoporous films functionalisation. Different kinds of chemical functions have been grafted at the surface of mesopore with the aim to modify their hydrophilicity or their chemical reactivity.
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https://tel.archives-ouvertes.fr/tel-00201895
Contributor : Sandrine Dourdain <>
Submitted on : Thursday, January 3, 2008 - 2:41:49 PM
Last modification on : Wednesday, November 4, 2020 - 1:47:28 PM
Long-term archiving on: : Tuesday, April 13, 2010 - 4:08:51 PM

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  • HAL Id : tel-00201895, version 1

Citation

Sandrine Dourdain. Caractérisation structurale, poreuse et mécanique de films minces de silice mésoporeuse.
Influence de la fonctionnalisation. Matière Condensée [cond-mat]. Université du Maine, 2006. Français. ⟨tel-00201895⟩

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