Résumé:

Dispersing colloidal particles (1nm-1µm) in fluids has been an empirical activity for a long time, either to create new materials (colloidal dispersions, emulsion stabilization) or to modify the properties of existing materials (polymer mechanical reinforcement for example, rheological changes). In the last decade, great efforts have led to a better control of the size, the shape or the functionality of small solid particles and it is possible now to better relate their characteristics to the final materials. We will discuss here the possibilities offered by complex fluids to design and organize nano-objects, but also how to use them to enhance the properties of a complex fluid. In the first part, I will have a short review on the properties of self-organized phases of surfactants, lyotropic and thermotropic liquid crystals and consider the main problems related to the dispersions of nanoparticles. We will discuss for example the attempts to orient Single Wall Carbon Nanotubes in a nematic phase, or to achieve bidimensional layers of nanoparticles in a smectic phase. In a second part I will discuss the enhancement of the properties of a complex fluid. I will particularly focus on the dispersion of magnetic particles in a liquid crystal and the role of the shape in increasing the magneto-optical properties of the nematic phase.