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Ce travail concerne l'étude des interactions bactéries /silicates grâce à de nouveaux matériaux ou gels de silice hybrides dopés en particules colloïdales de smectites (GSH). Les deux objectifs principaux sont la caractérisation physicochimique des GSH et l'amélioration des connaissances sur les mécanismes de l'altération minérale grâce aux GSH. Dans le premier volet de la thèse, nous avons ainsi pu mettre en évidence que le gel est constitué d'une matrice siliceuse particulaire de nature fractale dans laquelle les particules minérales sont dispersées. La structure des GSH est stabilisée par le traitement hydrothermal choisi (type autoclave). Dans le second volet de la thèse, l'altération minérale est étudiée pour des GSH à concentration variable en particules minérales, à teneur élevée (NAu-2) ou basse (SWy-2) en fer. Il est ainsi montré que la diffusion des acides organiques et des sidérophores dans le GSH, hors adhésion ou formation d'un biofilm en surface des minéraux, est suffisante pour altérer efficacement les particules minérales. La mise en évidence de gradients de protons locaux produits par la bactérie en interaction avec les GSH peut également expliquer l'efficacité biotique de la dissolution minérale par rapport à des conditions abiotiques. En conclusion, les points forts et les limites de l'utilisation d'un matériau hybride type GSH pour cibler les interactions minéral/microorganismes sont discutés / This work deals with the study of bacteria/silicate interactions by using new hybrid materials, i.e. hybrid silica gel dopped with colloidal smectite particles (HSG). The aims are (1) to characterize HSG physicochemical properties and (2) to get a better knowledge about mineral/bacteria interactions. In a first part of the thesis, it is shown that HSG is a fractal silica network containing well-dispersed mineral particles. Hydrothermal treatment is necessary to stabilize the HSG structure. In the second part, it is shown that diffusion of organic acids and siderophores is sufficient to explain the high efficiency of bacterial action compared to abiotic treatments. Preventing bacterial adhesion or biofilm formation at the mineral surface permits to enhance the influence of metabolites diffusion. To conclude, the advantages and limits of using HSG in environmental studies are discussed

A prospect in utilizing thermal energy in development of energy systems is by the useof phase change materials (PCMs). PCMs are materials that can store and releaseenergy during phase changes, e.g. from solid to liquid. By-products from the woodand pulping industry could be of interest in this area, in part to add value to theby-products, enhance the yield of the raw product of wood and become less dependenton fossil based fuels. Capsules of lignin and tall oil pitch/tall oil fatty acids weresuccessfully produced with a straightforward coprecipitation method. The solventused was acetone and the antisolvent was distilled water. Dynamic light scatteringanalysis showed average particle diameters of 300 to 500 nm and fairly lowpolydispersity, between 0.2 to 0.3, indicating spherical particles. Scanning electronmicroscopy confirmed particle size and the formation of capsules with shell thicknessless than 100 nm. The particle dispersions showed sufficiently high zeta potential tomaintain a stable colloidal system. Thermal analysis confirmed stability in atemperature range of at least -40 °C to +50 °C, and resistance to decomposition at leastup to around 200 °C. There were also indications of enhanced thermal stability of talloil pitch due to encapsulation. A desired feature for a phase change material is theability to keep a constant temperature during phase change. Regarding using thesynthesized material as phase change material, the results show that the temperaturerange in which phase change, such as melting, occurs is too broad. Latent heat of fusionof 4.7 J/g for the material is also very low compared with commercial phase changematerials. Further studies in modifying the system to impact melting point andenhancement of latent heat is needed if the material should be applicable as an efficientand competitive phase change material.

This master´s thesis focuses on duplex microstructures preparation by powder metallurgy. A hybrid material can be created by combining two or more existing materials in different geometries, and thus the newly formed composite can provide a superposition of the properties of the starting materials (powders). This means that it will have an improved combination of the required properties. The theoretical part describes in detail the hybrid materials and the architectured materials that contain highly controlled structures. Structure control allows to change the variety of possible geometries and opens up a number of other useful properties. Therefore, this thesis also deals with the mechanical alloying and SPS. The experimental part describes procedures of preparation of four samples of composites with a duplex structure from a powder of a significantly tough alloy (austenitic steel 316L) in combination with a powder of a significantly strong alloy (titanium carbonitride). A crucial part of this thesis is characterization of these four samples by electron microscopy methods (SEM, TEM, EDS) and supported by hardness measuring.

[pt] O objetivo da pesquisa foi dedicado à preparação de novos materiais híbridos à base de sílica contendo sistemas moleculares ou nanométricos de carbono com sistema de elétrons pi conjugados, imobilizados covalentemente para posterior aplicações como adsorventes e eletrodos para pré-concentração e determinação de compostos aromáticos. Deste modo, propôs-se o desenvolvimento das metodologias para as imobilizações covalentes de antraceno (Ant), pontos quânticos de óxido de grafeno (GOQDs) e nanopontos de carbono (CDs) na superfície da sílica (SiO2). Estes compostos são constituídos de sistemas conjugados de elétrons pi e, portanto, podem formar interação intramolecular de empilhamento pi–pi com compostos aromáticos. Nanocompósito de GOQDs imobilizados foi preparado através da interação covalente de fragmentos nanoméricos de óxido de grafeno (GO). Três tipos de SiO2-Ant foram obtidos através de abordagem de montagem da superfície pela reação de alquilação condensação de sílica modificada com grupos aminopropila. Estes materiais podem ter diferentes arranjos de ligantes de antraceno na superfície da sílica e, portanto, podem apresentar diferentes propriedades doadoras de elétrons-pi. Nanocompósitos de sílica gel com CDs imobilizados foram preparados por duas abordagens diferentes. Na primeira, os CDs foram obtidos a partir do ácido cítrico como material de partida e posteriormente imobilizados em sílica. O segundo método consistiu no uso de sílica gel porosa como nanorreator para a preparação de CDs. Este método é simples e robusto, o qual permite um maior controle do tamanho e da composição do nanomaterial. Além disso, os efeitos da modificação da sílica, tamanho dos poros, tempo de síntese, estabilidade hidrolítica, tamanho das nanopartículas de carbono e rendimento quântico da fluorescência foram avaliados. Foi demonstrado que a carbonização do gel aminosilica com ácido cítrico incorporado resultou na formação de CDs não imobilizados e CDs imobilizados. Devido à forte fixação na superfície, os CDs podem ser facilmente purificados através de simples lavagem do nanocompósito com água. Os C-pontos preparados apresentaram fotoluminescência independente de excitação a 445 nm com rendimento quântico até 80 porcento, o que os tornam atraentes para aplicação bioanalítica. O nanocompósito imobilizado com GOQDs foi preparado por ligações covalentes dos fragmentos de GO em nanoescala. A composição da camada superficial de todos adsorventes foi determinada a partir de análises elementares e termogravimétricas, fotoelétrons de raios X, ressonância magnética nuclear no estado sólido, Raman, FTIR e espectroscopia de fluorescência. As propriedades texturais dos adsorventes foram determinadas, bem como a cinética de imobilização do ligante, o grau de transformação da superfície e a estabilidade hidrolítica dos grupos enxertados, o efeito da porosidade da sílica no grau de conversão do ligante. As propriedades de adsorção dos materiais foram avaliados pela extração em fáse sólida nos modos dinâmico e estático para os compostos modelos azul de metileno e antraceno em várias fases móveis aquosas-orgânicas e orgânicas, na presença de componentes interferentes. Os nanomateriais obtidos apresentaram maior afinidade para compostos aromáticos do que os cartuchos comerciais C18 para extração em fase sólida (SPE) de fases orgânicas móveis que permitem a separação em uma etapa dos hidrocarbonetos aromáticos policíclicos (PAHs) na matriz com alta concentração de ácidos graxos. Ademais, sílica gel com GOQDs imobilizados foi usado para análise eletroquímica de antibióticos e hormônios selecionados. O eletrodo demonstrou atividade eletrocatalítica em relação ao estriol (ET), dietilestilbestrol (DES), sulfametoxazol (SMZ) e trimetoprim (TMP) que possibilitaram determinar esses analitos com até 0.009 μmol L(-1) (ET). / [en] The objective of the present research was devoted to the preparation of new silica-based hybrid materials having covalently immobilized carbon-containing molecular and nanometric systems with delocalized pi-electrons that can be used as adsorbents and electrodes for preconcentration and determination of aromatic compounds. For this purpose, methodologies for covalent immobilization of anthracene (Ant), graphene oxide quantum dotes (GOQDs) and carbon nanodots (CDs) on silica surface (SiO2) have been developed. These compounds have a conjugated system of pi-electrons and thus can form intramolecular pi–pi stacking interaction with aromatic compounds. The nanocomposite with immobilized GOQDs was prepared by covalent immobilization of nanoscale graphene oxide (GO) fragments. Three sets of SiO2-Ant were obtained using reaction surface assembling reactions by alkylation and condensation of silica with immobilized primary amines. These materials can have different arrangements of anthracene ligands on silica surface and so pi-donor properties. Silica gel nanocomposites with immobilized CDs were prepared by two different approaches. For the first one, the CDs were obtained from the molecular precursor and then immobilized on silica. For the second method, CDs were prepared by nanoreactor approach directly in silica gel pores. The second method is facile and robust and also allows better control of the particle size and composition. The effects of silica gel modification, pore size, synthesis time, hydrolytic stability, carbon nanoparticle size and quantum yield of the fluorescence were studied. It was demonstrated that the carbonization of aminosilica gel with embedded citric acid resulted in the formation of unbound CDs and immobilized CDs. Due to firm attachment to the surface CDs can be easily separated from low-molecular-weight impurities and CDs by simple rinsing of the nanocomposite with water. As prepared CDs demonstrate excitation-independent photoluminescence at 445 nm with quantum yield up to 80 percent that makes them attractive for bioanalytical application. The composition of the surface layer of the adsorbents was determined from elemental and thermogravimetric analysis, X-ray photoelectron, solid nuclear magnetic resonance, Raman, FTIR, and fluorescent spectroscopy. The textural properties of the adsorbents were determined as well as ligand immobilization kinetics, the degree of surface transformation and hydrolytic stability of the grafted groups, the effect of silica porosity on ligand conversion degree. The adsorption properties of the materials were studied in dynamic and static solid-phase extraction (SPE) modes for the model compounds methylene blue and anthracene in various aqueous-organic and organic mobile phases, in the presence of interfering components. It was demonstrated that studied materials have a higher affinity towards aromatic compounds than commercial C18 SPE cartridges in organic mobile phases that allow one-step separation of polycyclic aromatic hydrocarbons in the matrix with a high concentration of fatty acids. Also, silica-immobilized GOQDs was used for electrochemical analysis of selected antibiotics and hormones. The electrode demonstrated electrocatalytic activity towards estriol (ET), diethylstilbestrol (DES), sulfamethoxazole (SMZ), and trimethoprim (TMP) that made it possible to determine these analytes with up to 9 nmol L(-1) (ET).

No description available.

Amino-functionalized organic–inorganic hybrid materials with a narrow distributed nanostructure of 2–4 nm in size were obtained by means of a template-free and non-aqueous procedure. Simultaneous twin polymerization of novel amino group containing twin monomers with 2,2′-spirobi[4H-1,3,2-benzodioxasiline] has been applied for this purpose. The amino groups of the organic–inorganic hybrid material are useful for post derivatization. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Polyamide 6/SiO2 hybrid materials were produced by a coupled polymerization reaction of three monomeric components namely 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one) (Si(ε-CL)4), 6-aminocaproic acid (ε-ACA) and ε-caprolactam (ε-CL) within one process. Si(ε-CL)4 together with ε-ACA has been found suitable as a precursor monomer for the silica and PA6 components. The accurate adjustment of the molar ratio of both components, as well as the combination of the overall process for producing the polyamide 6/SiO2 hybrid material with the hydrolytic ring opening polymerization of ε-caprolactam is of great importance to achieve homogeneous products with a low extractable content. Water in comparison with ε-ACA has been found unsuitable as an oxygen source to produce uniformly distributed silica. The procedure was carried out in a commercial laboratory autoclave at 8 bar initial pressure. The molecular structure and morphology of the hybrid materials have been investigated by solid state 29Si and 13C NMR spectroscopy, DSC and FTIR spectroscopy and electron microscopy measurements. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

The acid and base catalyzed simultaneous twin polymerization (STP) of various 2,2′-disubstituted 4H-1,3,2-benzodioxasiline derivatives 2a–d with 2,2′-spirobi[4H-1,3,2-benzodioxasiline] (1) are presented in this paper. The products are nanostructured ternary organic–inorganic hybrid materials consisting of a cross-linked organic polymer, silica and a disubstituted polysiloxane. It can be demonstrated whether and in which extent the copolymerization of the two inorganic fragments of 1 and 2 takes place among the STP and how the molar ratio of the two components determines the structure formation of the resulting hybrid material. Steric and electronic effects of the substituents at the silicon center of 2 on the molecular structure formation and the morphology of the resulting hybrid material were investigated by means of solid state CP MAS 29Si and 13C NMR spectroscopy as well as high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The mechanical properties (hardness and Young's modulus) of the hybrid materials were analyzed by means of nanoindentation measurements. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Ce manuscrit présente la synthèse de nouveaux matériaux élastomères dérivés du caoutchouc naturel et de monomères organiques possédant des propriétés antifouling et/ou antibactériennes, liés de manière covalente au réseau polymère. Des monomères acrylates originaux comportant un groupement bioactif (un groupe guanidinium ou des dérivés de l'acide Zostérique) ont été synthétisés et co-polymérisés avec des oligomères acrylates téléchéliques. Aucun relargage significatif des monomères bioactifs n’'a eu lieu après immersion dans l'eau. Les films auto-portés synthétisés uniquement à partir des oligoisoprènes de type acrylate ont montré une faible activité antibactérienne qui a pu être drastiquement améliorée en intégrant aux films des monomères bioactifs. Les revêtements se sont montrés actifs contre plusieurs souches de bactéries pathogènes, parmi lesquelles P.aeruginosa, S.aureus, Bacillus subtilis et S.epidermidis. Afin de greffer de manière covalente des brosses d'oligoisoprène sur des surfaces, de nouveaux oligoisoprènes bifonctionnels comportant un groupe terminal alkoxy-silane ont été préparés puis couplés avec des matériaux à base de silicium. Une autre approche a également été étudiée, consistant à pré-fonctionnaliser la surface avec des groupements amino puis à partir de ces fonctions à greffer des oligomères ayant des extrémités carbonylés. La post-polymérisation à partir des extrémités de chaîne libres à la surface a donné un revêtement épais d’'oligoisoprène offrant une forte résistance à l'immersion dans des solvants (eau, THF). De cette manière, nous avons pu accéder à des couches moléculaires denses et liées, à des films minces et à des revêtements épais. / This manuscript presents the synthesis of new elastomeric materials based on natural rubber derived building blocks and organic monomers having antifouling and/or antibacterial properties, covalently bound to the polymer network. Original acrylate monomers bearing an organic bioactive moiety (a Guanidinium group or Zosteric acid derivates) were synthesized and co-polymerized with telechelic acrylate oligomers from polyisoprene. No significant leaching of the bioactive monomers occurred and the material resisted to long water immersions. Freestanding films prepared from acrylate oligoisoprenes also showed a weak antibiofouling activity which was drastically increased by integrating the guanidinium and the Zosteric acid monomers. The coatings were active against several strains of pathogenic bacteria among which Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Staphylococcus epidermidis. In order to covalently graft oligoisoprenes to surfaces, new bifunctional oligoisoprenes bearing an alkoxy-silane end moiety were designed and coupled with silicon-containing materials. An alternative approach was followed by prefunctionalizing the surface with amino groups and by covalently grafting oligomers with carbonyl chain-ends. Post-polymerization from the surface free chain-ends resulted in a thick oligoisoprene coating with strong resistance to solvent immersion (water, THF). In this way, we were able to build dense and tethered molecular layers, thin films and thick coatings.