Microemulsions as Synthesis Medium

3 Microemulsions as Synthesis Medium. - Since this paper deals with the synthesis of metal-based catalysts, we will focus on the description of water in oil microemulsions which have been recognised as suitable systems for the preparation of nanoparticles. 

Reversed micelles are defined as small aggregates formed by surfactant molecules surrounding a water core of a well-defined nanometer size. Potentially, the water droplets in the microemulsion may be considered as reaction media, microreactors, for the synthesis of particles. Reactants are confined within such dispersed droplets, provided that water-soluble precursors are used.  

This structure has been shown to be the most suitable for the preparation of fine inorganic colloidal particles due to the size of the aggregates and their monodispersity and also due to the fact that most of the metal precursors are water-soluble. The water core of the reversed micelles will host the hydrophilic metal salts that will turn, after a reduction step, into metallic particles. 

The extension of the reversed micelle region within the ternary system depends, among other factors, on the nature of the surfactant (ionic, cationic, and non-ionic) and the solvent. 

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