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Structuration par voie colloïdale de nanopoudres de boehmite à partir de systèmes mixtes organique/inorganique

Abstract : Research in this field is multidisciplinary and relies largely on the development of nanomaterials. These are, in fact, the raw materials of nanoscience and open to industry extremely broad prospects. In the field of material sciences, nanostructured materials, among them nanostructured ceramics have grown considerably in recent years. Development of ceramic requires a mastery of production processes that achieve appropriate microstructures in the development of dense materials for various applications such biomédicals. Recent developments include hybrid and bio-inspired materials; the problems of shaping and multi-scale structure of these encourage the development of new processes such as the new so-called bottom-up approach of manufacturing and make macroscopic material from its nanoparticles. In this context, the work of this PhD aim to facilitate, through surface modification, the development of an original layout technique for the development of ceramics from a material nano-oxide type: granulation coagulation. We were interested in the case of a boehmite nanopowder (AlO(OH)). However, this nanoscale boehmite powder has many instabilities in suspension. Indeed, the powder is subjected to strong gelation as function of pH and at low concentrations. It is necessary in this case to obtain a stable suspension by modifying the surface properties. Accordingly, a part of this work is devoted to surface functionalization by organosilanes. This surface modification, however, is only one stage to obtain a hybrid particle comprised of a heart of boehmite and a polymeric layer. In reality, the grafting organosilane (MPS) at the surface permit to create a bridge between the inorganic core and organic outer part consists of latex. The boehmite-MPS-latex hybrid material thus obtained can be used in a new colloidal shaping technique inspired by heterocoagulation granulation. In aqueous medium, the opposite polarity of the charges of the surfaces of two different entities leads to heterocoagulation in suspension. Clotting observed in this thesis, connects two identical particles with each, the two charges opposite to the surface. The principle of the granulation is to induce, under the effect the rotational movement, the coalescence of the agglomerates by forcing their surfaces to interact by mutual contact. By selecting the formulation, coalescence leads to the development of homogeneous spherical objects in size and shape.
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Fahouzi Belounis. Structuration par voie colloïdale de nanopoudres de boehmite à partir de systèmes mixtes organique/inorganique. Matériaux. Université de Limoges, 2015. Français. ⟨NNT : 2015LIMO0052⟩. ⟨tel-01216575⟩

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