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Publications: Articles

Toutes :: 2009, 2011, 2013
Tous :: A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, R, S, T, U, V, W, Y, Z 
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Zhang, H.Y., Cleymand, F., Noel, C., Kahn, C.J.F., Linder, M., Dahoun, A., Henrion, G. and Arab-Tehrany, E.
Carbohydrate Polymers, 93(2):401-411

Resume: This work addresses the functionalization of chitosan thin films and its nanoliposomes blend films by a microwave-excited Ar/N2/H2 surface-wave plasma treatment which was found an effective tool to modify surface properties. Changes in the film properties (wettability, chemical composition, morphology) induced by the plasma treatment are studied using water contact angle measurements, X-ray photoelectron spectroscopy and scanning probe microscopy. The results suggest that hydrophilicity of the films is improved by plasma treatment in a plasma condition dependency manner. Water contact angle of chitosan films before and after plasma treatment are, respectively, 101° and 27°. Besides chemical changes on the surface, the nanoliposomes incorporation and plasma treatment also induce morphological modifications. Moreover, a correlation is found between the nanoliposomes composition and size, and the effects of plasma treatment. It is shown that the plasma treatment significantly improves the chitosan film functionalization. The effect of N2 content (88% and 100%) in the plasma gas mixture on the film etching is also pointed out.

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

Ochoa, E.A., Droppa, R., Basso, R.L.O., Morales, M., Cucatti, S., Zagonel, L.F., Czerwiec, T., Dos Santos, M.C., Figueroa, C.A. and Alvarez, F.
Materials Chemistry and Physics, 143:116-123

Resume: The low energy (similar to 50-350 eV) noble gases ion bombardment of the steel surface shows that the pre-treatments increase nitrogen diffusion by modifying the outermost structure of the material. The surface microstructure and morphology of the studied samples were characterized by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The crystalline and chemical structures in the outermost layers of the surface were analyzed by grazing angle X-ray diffraction (GAXRD) and photoemission electron spectroscopy (XPS). Temperature effusion studies of the implanted ions are used to elucidate the noble gases site localization in the network. The local compressive stress induced by the nearby iron atoms on the core level electron wave functions of the trapped noble gases are studied by photoemission electron spectroscopy (XPS) and interpreted considering a simple mechanical model. Nano-hardness measurements show the dependence of the material elastic constant on the energy of the implanted noble gases. Although the ion implantation range is about few nanometers, the atomic attrition effect is larger enough to modify the material structure in the range of micrometers. Two material stress zones were detected where the outermost layers shows compressive stress and the underneath layers shows tensile stress. The implanted noble gases can be easily removed by heating. A diffusion model for polycrystalline-phase systems is used in order to discuss the influence of the atomic attrition on the N diffusion coefficient. The concomitant effect of grain refining, stress, and surface texture on the enhancing nitrogen diffusion effect is discussed.

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

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