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Theses

Elaboration de surfaces à mouillabilité photo-contrôlable

Abstract : This work, which joins within the framework of researches on surfaces specific properties, concerned the concept of the elaboration of surfaces with photoswitchable wettability. Principle is based on the creation of a monolayer of molecules with photoswitchable transition modifying the state of polarization of the surface. To reach this objective and considering the potential applications, we directed our investigations to two types of support: polymer and silicon surfaces.
The way of elaboration on polymer surfaces consisted in fonctionnalizing the surface of a commercial polypropylene film by a CO2-plasma treatment. The surface chemical functions concentration introduced on the polymer surface was determined by combining, for the first time, the results of the X-ray photoelectron spectroscopy ( XPS) and those of a fluorescence titration by means of a Raman spectrometer. The way of elaboration allows, for the first time to our knowledge, the grafting of chromophores only on the extreme surface of the material.
Our results allowed to attribute the reversible variations of the wettability of the surface not to a modification of the polarity of the surface due to the isomerization of molecules grafted on the surface of the polymer film, but to a reversible variation of the surface morphology due to the isomerization of azo compounds diffused in the material.
In the objective of applications in microfluidic and to have a better understanding of the parameters influencing the photo-control of the wettability, we set up several ways of preparation to allow the grafting of a molecular layer of chromophores on a silicon surface.
All works added to the analysis of the results published in the literature allowed to contribute to a better understanding of the parameters which can influence the photo-control of the surface wettability. So, for silicon surfaces, the choice of the chromophore is important because to benefit from a big variation of wettability, the surface has to consist of chromophores isomers possessing a strong difference of dipolar moment. Another important parameter seems to be the compactness of the chromophore layer grafted on the silicon surface because the more this layer is compact, the more the wettability variation observed is important.
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Submitted on : Friday, December 17, 2004 - 11:31:31 AM
Last modification on : Tuesday, March 31, 2020 - 3:20:49 PM

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  • HAL Id : tel-00007804, version 1

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Nicolas Delorme. Elaboration de surfaces à mouillabilité photo-contrôlable. Matière Condensée [cond-mat]. Université du Maine, 2004. Français. ⟨tel-00007804⟩

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