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1-Microevaporation - Microfluidics is the branch of fluid mechanics dedicated to the study of flows in the channel withdimensions between 1 micron and 100 micron. The object of this chapter is to illustrate the basicprinciples and possible applications of microfluidic chip, called microevaporator. In the first part ofthe chapter, we present a detailed description of the physics of microevaporators using analyticalarguments, and describe some applications. In the second part of the chapter, we present theexperimental protocol of engineering of micro evaporator and different type of microfluidics device.2- On-chip microspectroscopy - The object of this chapter is to illustrate a method to measure absorption spectra during theprocess of growth of our materials in our microfluidic tools. The aim is to make an opticalcharacterization of our micro materials and to carry-out a spatio-temporal study of kineticproperties of our dispersion under study. This instrumental chapter presents the theoretical basis !of the method we used.3-Role of colloidal stability in the growth of micromaterials - We used combined microspectroscopy and videomicroscopy to follow the nucleation and growth ofmaterials made of core-shell Ag@SiO2 NPs in micro evaporators.!We evidence that the growth is actually not always possible, and instead precipitation may occurduring the concentration process. This event is governed by the concentration of dispersion in thereservoir and we assume that its origin come from ionic species that are concentrated all togetherwith the NPs and may alter the colloidal stability en route towards high concentration. 4-Microfluidic-induced growth and shape-up of three-dimensional extended arrays of denselypacked nano particles - In this chapter I present in details microfluidic evaporation experiments to engineer various denselypacked 3D arrays of NPs.5-Bulk metamaterials assembled by microfluidic evaporation - In this chapter I introduced the technique we used (microspot ellipsometry) in close collaborationswith V.Kravets and A.Grigorenko(University of Manchester) and with A.Aradian, P.Barois, A.Baron,K.Ehrhardt(CRPP, Pessac) to characterized the solids made of densely packed NPs. I describe theconstraints that emerge from the coupling between the small size of our materials and the opticalrequirements, the analysis and interpretation of the ellipsometry experiments show that for thematerial with high volume fraction of metal exists the strong electrical coupling between the NPsand the materials display an extremely high refraction index in the near infra-red regime.

Tesis por compendio / [ES] En los últimos años, la química se ha convertido en una herramienta esencial en la búsqueda de soluciones al cambio climático y la escasez de recursos. En este sentido, la catálisis ha desempeñado un papel importante en el desarrollo de materiales y procesos cada vez más limpios y eficientes. Dada la asequibilidad y la abundancia de materiales a base de carbono en comparación con los catalizadores tradicionales, como los metales preciosos y los óxidos metálicos, el grafeno es considerado un material prometedor para una amplia gama de aplicaciones. En este contexto, en la presente tesis doctoral se describe el empleo de poliestireno como precursor de grafeno, así como su uso para desarrollar un método general de exfoliación y formación de heterouniones con propiedades electrocatalíticas. Además, se describe otros materiales grafíticos, cuyas paredes están constituidas por unas pocas láminas de grafeno. Estos carbonos grafíticos 3D ultramicroporosos son capaces de promover reacciones como la oxidación aeróbica del alcohol bencílico o la ruptura fotocatalítica de la molécula del agua. / [CA] En els últims anys, la química s'ha convertit en una eina essencial en la recerca de solucions a el canvi climàtic i l'escassetat de recursos. En aquest sentit, la catàlisi ha tingut un paper important en el desenvolupament de materials i processos cada vegada més nets i eficients. Donada la assequibilitat i l'abundància de materials a base de carboni en comparació amb els catalitzadors tradicionals com ara els metalls preciosos i els òxids metàl·lics, el grafè és considerat un material prometedor per a una àmplia gamma d'aplicacions. En aquest context, en la present tesi doctoral es descriu l'ús de poliestirè com a precursor de grafè, així com el seu ús per a desenvolupar un mètode general d'exfoliació i formació de heterojuncions amb propietats electrocatalítiques. A més, es descriuen altres materials grafítics, les parets del quals estan constituïdes per unes poques làmines de grafè. Aquests carbonis grafítics 3D ultramicroporosos són capaços de promoure reaccions com l'oxidació aeròbica de l'alcohol benzílic o la ruptura fotocatalítica de la molècula d'aigua. / [EN] In the recent years, chemistry has become a crucial tool in the quest for solutions against climate change and resource scarcity. In this regard, catalysis plays an important role in the development of more efficient and sustainable materials and processes. Given the availability and low cost of carbon-based materials compared to traditional catalysts such as noble metals or metal oxides, graphene is considered a promising candidate for a wide variety of applications. In this context, the present doctoral thesis describes the use of polystyrene not only as graphene precursor but also as exfoliating agent to prepare heterojunctions with electrocatalytic properties. In addition, a general procedure to obtain graphitic materials comprising few layers graphene walls is also described. These ultramicroporous 3D graphitic carbons can promote the aerobic oxidation of benzilic acid or the photocatalytic water splitting reaction. / Rendón Patiño, A. (2021). Materiales a base de grafenos como foto-(electro)catalizadores para la generación de hidrógeno [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172379 / Compendio

Parts made out of titanium alloys demonstrate anisotropic mechanical properties when manufactured by electron beam melting, an emerging additive manufacturing technique. Understanding the process history dependent heterogeneous microstructure, and its effect on mechanical properties is crucial in determining the performance of additively manufactured titanium alloys as the mechanical behavior heavily relies on the underlying microstructural features. This thesis work focuses on combined experimental and computational techniques for microstructure characterization, synthetic microstructure generation, mechanical property measurement, and mechanical behavior modeling of polycrystalline materials, with special focus on dual phase titanium alloys. Macroscopic mechanical property measurements and multi-modal microstructure characterizations (high energy X-ray diffraction, computed tomography and optical microscopy) are performed on additively manufactured Ti-6Al-4V parts, revealing the heterogeneity of the microstructure and properties with respect to the build height. Because characterizing and testing every location within a build is not practical, a computational methodology is established in order to reduce the time and cost spent on microstructure-property database creation. First a statistical volume element size is determined for the Fast Fourier Transform based micromechanical modeling technique through a sensitivity study performed on an experimental Ni-based superalloy and syntheticW, Cu, Ni and Ti structures, showing that as the contrast of properties (e.g., texture, field localization, anisotropy, rate-sensitivity) increases, so does the minimum simulation domain size requirement. In all deformation regimes a minimum volume element is defined for both single and dual phase materials. The database is then expanded by generating statistically representative Ti structures which are modified for features of interest, e.g., lath thickness, grain size and orientation distribution, to be used in spectral full-field micromechanical modeling. The relative effect of the chosen microstructural features is quantified through comparisons of average and local field distributions. Fast Fourier transform based technique, being a spectral, full-field deformation modeling tool, is shown to be capable of capturing the relative contribution from varying microstructural features such as phase fractions, grain morphology/ size and texture on the overall mechanical properties as the results indicate that the mean field behavior is predominantly controlled by the alpha phase fraction and the prior beta phase orientation.

Les métamatériaux sont définis comme étant des matériaux artificiels présentant des propriétés exotiques qui modifient la propagation des ondes électromagnétiques. À la fin des années 90, Pendry et al. démontrèrent théoriquement qu'il est possible de générer de tels métamatériaux, grâce à des structures particulières au sein du matériau (le fameux "splitring resonator"). Les métamatériaux sont donc structurés à une échelle inférieure à la longueur d'onde incidente, et décrits par une permittivité et une perméabilité effective. En 2000, Smith et al. fabriquèrent le premier métamatériau mais dans la gamme micro-onde. Les perspectives dans le domaine de l'optique (300800 nm) sont très prometteuses, mais le transfert des technologies utilisées en micro-ondes rencontre des obstacles. Un des défis dans le domaine émergent des métamatériaux est d'assembler à grande échelle des nanoparticules NPs (10-50 nm) en des super-réseaux présentant des propriétés collectives. Des nanostructures tridimensionnelles de matériaux nobles, ayant de fortes réponses plasmoniques, peuvent en effet générer des matériaux aux nouvelles propriétés optiques. Cette thèse fait partie du projet européen METACHEM, dont le but est de fabriquer des métamatériaux dans le domaine de l'infrarouge et du visible, en se basant sur l'utilisation de la nanochimie et de l'assemblage de matériaux. Plus précisément, ce travail de thèse se situe à l'interface entre les groupes de chimie qui synthétisent des nanoparticules en dispersion, et les groupes de caractérisation optique des matériaux. Dans ce travail de thèse, nous utilisons une technique originale la microévaporation basée sur les outils microfluidiques, afin de générer de façon contrôlée des assemblées 3D de nanoparticules (dimensions typiques 1 mm10 m 50 m). / 1-Microevaporation - Microfluidics is the branch of fluid mechanics dedicated to the study of flows in the channel withdimensions between 1 micron and 100 micron. The object of this chapter is to illustrate the basicprinciples and possible applications of microfluidic chip, called microevaporator. In the first part ofthe chapter, we present a detailed description of the physics of microevaporators using analyticalarguments, and describe some applications. In the second part of the chapter, we present theexperimental protocol of engineering of micro evaporator and different type of microfluidics device.2- On-chip microspectroscopy - The object of this chapter is to illustrate a method to measure absorption spectra during theprocess of growth of our materials in our microfluidic tools. The aim is to make an opticalcharacterization of our micro materials and to carry-out a spatio-temporal study of kineticproperties of our dispersion under study. This instrumental chapter presents the theoretical basis !of the method we used.3-Role of colloidal stability in the growth of micromaterials - We used combined microspectroscopy and videomicroscopy to follow the nucleation and growth ofmaterials made of core-shell Ag@SiO2 NPs in micro evaporators.!We evidence that the growth is actually not always possible, and instead precipitation may occurduring the concentration process. This event is governed by the concentration of dispersion in thereservoir and we assume that its origin come from ionic species that are concentrated all togetherwith the NPs and may alter the colloidal stability en route towards high concentration. 4-Microfluidic-induced growth and shape-up of three-dimensional extended arrays of denselypacked nano particles - In this chapter I present in details microfluidic evaporation experiments to engineer various denselypacked 3D arrays of NPs.5-Bulk metamaterials assembled by microfluidic evaporation - In this chapter I introduced the technique we used (microspot ellipsometry) in close collaborationswith V.Kravets and A.Grigorenko(University of Manchester) and with A.Aradian, P.Barois, A.Baron,K.Ehrhardt(CRPP, Pessac) to characterized the solids made of densely packed NPs. I describe theconstraints that emerge from the coupling between the small size of our materials and the opticalrequirements, the analysis and interpretation of the ellipsometry experiments show that for thematerial with high volume fraction of metal exists the strong electrical coupling between the NPsand the materials display an extremely high refraction index in the near infra-red regime.