In the aim of protecting stainless steel surfaces against protein and/or bacterial adhesion, thin films including the glycosidase hen egg white lysozyme (HEWL) and/or the synthetic polymer poly(ethylene glycol) (PEG) were covalently coated onto flat substrates by wet chemical processes. Chemical grafting of both species was carried out by covalent binding to surfaces pretreated by the polyamine poly(ethylene imine) (PEI). Surfaces were characterized at each step of functionalization by means of reflection-absorption infrared spectroscopy by modulation of polarization (PM-RAIRS) and X-ray photoelectron spectroscopy (XPS) to determine the atomic and molecular composition of the interfaces, respectively. Then, the ability of the so-modified surfaces to prevent protein adsorption and bacterial adhesion together with their biocide properties were demonstrated by three local tests employing bovine serum albumin (BSA), and the bacteria Listeria ivanovii and Micrococcus luteus. A new test was implemented to assess the local enzymatic properties of HEWL. Cografting of PEG and HEWL resulted in a surface with both antiadhesion and antibacterial properties.

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In order to explore the potentialities of xNy materials in multilayer-based solar selective coatings (SSC) for high temperature applications (T>500 ºC), the optical behavior of Cr1-x(Al)xNy films is studied in this work. Two sets of layers (CrNy and Cr1-xAlxNy) were prepared by direct current (DC) and high-power impulse magnetron sputtering (HiPIMS) technology. The deposition parameters: N2 flux, HiPIMS frequency and aluminum sputtering power, were modified to get a wide variety of stoichiometries. The composition, morphology, phases and electronic structure of the films were characterized in depth. The optical behavior was determined by UV-Vis-NIR and FTIR spectroscopies, and the optical constants were obtained from the measured transmittance and reflectance spectra based on appropriate dielectric function models. Our results indicate that small changes in the layer composition influence the optical constant. In particular, a metallic-like behavior was obtained for CrNy layers with N vacancies (CrN0.95 and CrN0.67 films) while a semiconductor-like behavior was observed for CrN1.08. Thus, the CrNy films can be used as effective absorber layer in multilayerbased SSC, and namely, the CrN0.67 film as an IR reflector/absorber layer too. Likewise, the optical properties of Cr1-xAlxNy layers can also be tuned from metallic to semiconductor-like behavior depending on the chemical composition. Indeed, the absorption coefficients of Cr1-xAlxNy films with optimized Al content and N-vacancies are comparable to those reported for state-of-the-art materials such as TiAlN or TiAlCrN. In addition, a Cr0.96Al0.04N0.89 film was found to be a suitable IR reflector/absorber layer.

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Tout matériau immergé en milieu marin se recouvre de composés azotés, protéines, carbohydrates, sels, silice, puis de bactérie en quelques heures, et d'un biofilm mature en quelques jours. Cela altère ses propriétés physico-chimiques, entraîne un risque accru de corrosion localisée et de biodétérioration, avec pour conséquences des coûts d'entretien et de nettoyage importants. Les peintures contenant des sels de tributylétain (TBT) utilisées jusqu'à présent pour protéger ces surfaces se sont avérées toxiques pour le milieu marin [1]. Elles sont désormais soumises à des normes internationales, avec une interdiction d'application des sels TBT effective depuis 2003, et une interdiction totale en 2008. Il est donc aujourd'hui nécessaire de rechercher des alternatives à ces peintures. La solution ici proposée consiste à agir sur les premières étapes de formation du biofilm, à savoir la fixation de protéines et des premières bactéries sur la surface. Pour cela, la surface est modifiée chimiquement et fonctionnalisée par des enzymes, lesquelles vont agir localement sur la bactérie par hydrolyse de certains constituants de sa paroi, empêchant ainsi son adhésion à la surface. Les différentes étapes du greffage ont été contrôlées par Infra Rouge et par Spectroscopie de Photoélectrons X. Ces analyses ont permis de valider chaque étape du greffage. En parallèle, un nouveau test enzymatique pour tester l'activité de l'enzyme greffée a été mis en place et validé. Il a permis de vérifier l'efficacité de l'enzyme greffée vis-à-vis d'une suspension bactérienne modèle.

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