Synthesis of smooth and microtextured films by acetylene magnetron discharge:Study of growth mechanisms and fabrication of superhydrophobic surfaces
(2010)
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Details
- Authors
- Supervisors
- Lucas , Stéphane
- Abstract
- (en) Superhydrophobic surfaces are used to avoid fog condensation, frost and also for preventing contamination. They are known as "self-cleaning", non wettable and water-repellent surfaces. The best known example in nature is found in the leaves of the Lotus plant (Nelumbo nucifera). Lotus leaves always remain clean because water droplets form spheres with very little adhesion to the surface and can easily roll off, collecting and removing contaminations. This self – cleaning effect, often called the “Lotus effect”, is due to a combination of a rough surface with special micro- and nanostructures, along with low surface energy materials. So far, artificial superhydrophobic surfaces have been produced mainly in two ways. One is to prepare a rough surface from a low surface energy material. This method is generally a simple one-step process, but presents a major drawback as it is applicable only to a small limited set of materials. The other way is to first obtain a rough coating and then to modify it with a low surface energy material. This enlarges potential applications because it can be applied to a wide variety of substrates such as silicon wafer, glass, metals, stainless steel and polymer surfaces. This is the chosen approach for this thesis. Finally, most of methods used to produce rough surfaces are multi-step processes and are not environment friendly because of their use of organic solvents. These drawbacks can be solved by plasma deposition, the method used in this work. One of the significant results of this work is the synthesis of microtextured films by pulsed magnetron discharge from acetylene and the proposition of a qualitative model to explain their growth mode. The microtextured films obtained have a unique morphology with nanoparticles and particular agglomerates (“microflowers”) present at the surface. To the best of our knowledge, this is the first time that such carbon based microstructures are observed. One of the challenges was to understand the formation of these unknown microstructures. The gas phase was analyzed by quadrupole mass spectrometry. The bulk structure of both smooth and microtextured films was determined by combining three techniques including IR spectroscopy, Raman spectroscopy and Laser Desorption / Ionization Fourier Transform Mass Spectrometry (LDI-FTMS). Finally, this thesis demonstrates that the microtextured films functionalized with fluorine are superhydrophobic surfaces. One of the perspectives is the elaboration of superhydrophobic surfaces without fluorine treatments, by maximizing the surface density of fractal structures (“microflowers”).
- Affiliations
Citations
De Vriendt, V. (2010). Synthesis of smooth and microtextured films by acetylene magnetron discharge:Study of growth mechanisms and fabrication of superhydrophobic surfaces. https://hdl.handle.net/2078.5/41238