This dissertation describes the characterization of layer-by-layer silica and titania coatings deposited using a protamine-induced method. It was found that silica coatings were thinner and more porous than titania coatings. These coatings were functionalized by immobilizing modified Glucose oxidase during the layer-by-layer buildup. The enzyme was found to retain higher activity in silica versus titania, with full retention of activity observed in one configuration. Immobilization in both materials resulted in enhanced thermal stability and proteolytic protection. The enzyme-functionalized coatings were then modified by the immobilization of silver nanoparticles to the exterior, and this biological/inorganic composite was tested for its antimicrobial activity against E. coli and S. aureus. Against E. coli the composite worked in a synergistic fashion, showing more potent antimicrobial activity when compared to either agent used alone. The enzyme modification method was then extended to Laccase, which was immobilized to carbon nanotubes and characterized as a biocathode. Modified laccase returned a nearly two-fold higher current density versus the native enzyme. Finally, synthetic peptides were tested for their ability to adsorb to silica and titanium-oxide surfaces and subsequently deposit titanium-oxide coatings, in an effort to better understand the structure-function relationships of mineralizing peptides.

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Title: The study on interactions of functional surfaces with biological systems Author: Ivana Víšová Department: Institute of Physics of the Czech Academy of Sciences, Department of optical and biophysical systems. Supervisor: RNDr. Hana Vaisocherová-Lísalová, Ph.D., Institute of Physics of the Czech Academy of Sciences, Department of optical and biophysical systems. Abstract: This work is devoted to the study of processes influencing the performance of functional antifouling polymer brush coatings and their interactions with complex biological media. Specifically, both results of the fundamental and applied research on the i) functionalization processes influencing coating resistance, ii) tailoring of the physico-chemical properties of the antifouling coatings to minimize the nonspecific interactions with complex biological samples, and iii) behavior and performance of the polymer brush coatings in varying environments are presented. Acrylamide and methacrylamide-based polymer brushes with side hydroxyl, carboxybetaine, and sulfobetaine groups were studied, showing the great potential of their optimized copolymer structures as tunable antifouling functionalizable platforms for cell research or biosensor applications. Moreover, newly developed procedures for antifouling properties recovery after EDC/NHC...

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Inscrite dans le cadre d’un projet ANR, la thèse porte sur l’étude et le développement des revêtements poudres UV en vue du recouvrement de panneaux de bois. La thèse détaille les spécificités de ces formulations et de la technologie associée afin de constituer une bibliographie solide propre à ce domaine. Les travaux expérimentaux se basent sur des formulations modèles comprenant une résine poudre UV (uréthane diacrylate ou polyester diméthacrylate) et un photoamorceur. Une étude mécanistique permet de montrer les influences de la température et de la viscosité, de l’intensité lumineuse et de l’atmosphère sur la réactivité des formulations modèles. Il est également démontré que les mécanismes de terminaison spécifiques à ces systèmes suivent des processus mixtes: bimoléculaire, pseudo-monomoléculaire et recombinaison des radicaux primaires. La prédominance des différents processus dépend de l’avancement de la réaction. La formation du réseau de réticulation est ensuite étudiée en fonction de la source d’irradiation: convoyeur semi-industriel doté de lampes UV ou système LED émettant autour de 395 nm. Les caractéristiques du réseau de réticulation (Tg, densité de réticulation, module d’Young) sont reliées aux propriétés des revêtements finaux (flexibilité, résistance à la rayure ou au solvant). L’utilisation d’acrylates multifonctionnels a un impact sur les longueurs de chaînes et la densité de réticulation. En vue d’applications spécifiques, il est finalement proposé d’incorporer une argile modifiée avec de l’Argent au sein des formulations modèles pour obtenir des revêtements poudres UV antibactériens homogènes possédant de bonnes propriétés de résistance. / In the frame of a project of the Agency National Research (France), the thesis deals with the study and the development of UV powder coatings dedicated to wood based panels. The work describes the main features of these formulations and the associated technology in order to offer a strong bibliography specific to this area. The experiments are based on model formulations containing an UV powder resin (diacrylate urethane or dimethacrylate polyester) and a photoinitiator. A mechanistic study allows highlighting the influence of temperature and viscosity, light intensity and atmosphere on the reactivity of the model formulations. It is also shown that the termination mechanisms specific to theses systems follow mixed processes: bimolecular, pseudo-monomolecular and primary radical termination. The predominance of the different processes is related to the reaction conversion. The building of the crosslinking network is then studied depending of the irradiation source: semi-industrial conveyor equipped with UV lamps or LED system emitting around 395 nm. The characteristics of the crosslinking network (Tg, crosslinking density, Young’s modulus) are linked to the final coatings properties (flexibility, scratch and solvent resistance). The incorporation of multifunctional acrylates affects the chains length and crosslinking density. To reach specific applications, it is finally proposed to add a silver-modified clay into model formulations to obtain homogeneous antibacterial UV powder coatings exhibiting good resistance properties.

Magnesium with two-thirds of the density compared to aluminium and one-quarter of steel, intrigues product developers and material scientists due to the light metal’s excellent combination of strength to weight ratio as well as their capability of being produced as a High Pressure Die Cast component compared to other ferrous or light metal alloys.   However, a magnesium alloy inherits some concerning drawbacks, limiting the exploitation in structural applications and mechanical design such as automotive, heavy machinery and aerospace components. The need for a magnesium alloy that could withstand a sufficient amount of wear, temperature and corrosive environment, leads towards the investigation and evaluation of a suitable, functional coating as a solution to exploit the evident advantages a magnesium alloy exhibits. A substantial amount of research is required in order to reduce an existing knowledge gap that is the ongoing development in the search for a sufficient functional coating and adherence capability to the highly reactive substrate that is a magnesium alloy.   This industrial master thesis is an early stage investigation to evaluate how the currently used aluminium substrate with an electrodeposited coating relate and compares to a heat-treated electroless deposited coating through tribological and thermophysical induced stresses. These properties are tested with proven industrial standard methods resulted in a comprehensive conclusion and discussion regarding the feasibility of applying the coating onto a commercial magnesium alloy closely related to the Mg-alloy developed by Husqvarna and thereby contributing to technological advances to the highly relevant topic within product development in materials engineering.