CONTEXT

Due to their specific physical properties (optic, magnetism, and conductivity), metal oxide nanoparticles are attracting a lot of industrial interest and are already used for numerous applications in cosmetics, for medical diagnosis or as medical tools, or as new devices for optical and electronic applications. The existing methods for the synthesis of metal oxide nanoparticles require either several complicated steps, expensive and complex set-ups, lead to low reaction rates or to uncontrolled sized and shaped particles.

These inventions relate to a new, simple, reliable and inexpensive method to synthesize metal or metal oxide nanoparticles displaying controlled and customized size and shape.

TECHNICAL DESCRIPTION

These particular inventions relate to versatile processes allowing control over size and shape, and leading to either metallic or metal oxide nanoparticles dispersable in every desirable solvent, especially in water.

The patented process displays 2 main advantages, compared to the existing ones:

1) it is a one step process involving simple products;

2) it takes place at room temperature.

The nano materials obtained can be stoked as powders and re-suspended on demand in every desirable solvent without neither ligand exchange nor the formation of interdigitated layers.

Metal oxides nanoparticles

In this case, the strategy is based on the use of water sensitive high energy organometallic complexes and on the very exothermic reactions that they display.

The kinetics of this reaction controls the formation of the nanomaterials.

Therefore a controlled hydrolysis and/or oxidation of the precursor in solution leads, in one step and at room temperature, to metal oxide nanoparticles.

The shape and size of these nanoparticles can be controlled by the different parameters of the system (such as the nature of the organometallic precursor, the ligands or surfactants present, the solvent used for example,) as well as their 2D and 3D organizations.

Specific physical properties can be achieved following such process like optical properties depending on the excitation wavelength or nanovaristors.

Magnetic metal oxide nanoparticles

Following the same process, magnetic nanoparticles can be prepared. Pure phase of iron oxide can be achieved such as maghemite (g-Fe₂O₃), wüstite (Fe_1-yO) or mixte metal oxide such as cobalt ferrite (CoFe₂O₄) nanoparticles.