Procedencia: Centro de Investigación en Materiales Avanzados

Abstract

Since first reported in 1982,[1] the microemulsion reaction method has been employed extensively for synthesis of a variety of metallic, metal oxide and other inorganic nanoparticles. It is well known that this soft method allows for the preparation of nanoparticles with a narrow size distribution, high specific surface area, good crystallinity and a performance which is differentiated and often superior to that of nanomaterials synthesized by other methods. Until recently, the totality of those investigations was based on water-in-oil (w/o) microemulsions. However, the use of w/o microemulsions requires high amounts of solvent, hindering its applications at the industrial scale. Hence, from a practical, environmental, and economical point of view, the possibility of using oil-in-water (o/w) microemulsions may be highly advantageous, since the major phase is water. Such novel approach implies the use of organometallic precursors, dissolved in nanometerscale oil droplets (stabilized by surfactant), and dispersed in the continuous aqueous phase; the precipitating agents, which are usually water-soluble, can be added directly to the microemulsion as an aqueous solutions withouth compromising microemulsion stability, which most likely involves an interfacial reaction mechanism. It was reported for the first time as a proof of concept by our group in 2009[2], and it was demonstrated that small nanoparticles with a narrow size distribution, good crystallinity and high SSA could be obtained. On the other hand, some investigation about the synthesis of nanoparticles in bicontinuous microemulsions is being developed by us and some other groups. [3]
In this contribution, we present an insight into the most important aspects of the use of microemulsions as confined reaction media, as well as examples of the synthesis of various nanomaterials obtained in W/O, O/W and bicontinuous microemulsions carried out by our research group; including nanoparticles, hybrid nanocrystals and hierarchical nanostructures.[4] The obtained results demonstrate the feasibility of this approach for the preparation of a great variety of nanomaterials with many potential applications, in particular those related with catalysis, energy scavenging and smart coatings.

Acknowledgements: We are grateful to CONACYT (Grant Number CB2011/166649).

References
1. M. Boutonnet, J. Kizzling, P. Stenius, Colloids and Surfaces 5 (1982), 209.
2. M. Sanchez-Dominguez, M. Boutonnet, C. Solans, J. Nanoparticle Res. 11 (2009), 1823.
3. K. Kowlgi, U. Lafont, M. Rappolt, G. Koper, J. Colloid Interface Sci. 372 (2012), 16.
4. M. Sanchez-Dominguez, K. Pemartin, M. Boutonnet, Curr. Opin. Colloid Interface Sci. 17 (2012) 297.