Emulsions: basic principles

mulsions are metastable colloids made out of two immiscible fluids, one being dispersed n the other, in the presence of surface active agents. Emulsion droplets exhibit all the lassical behaviours of metastable colloids: Brownian motion, reversible phase transitions s a result of droplet interactions that may be strongly modified, and irreversible transitions hat generally involve their destruction. They are obtained by shearing two immiscible fluids eading to the fragmentation of one phase into the other. Because the lifetime of emulsions may ecome significant (more than a year), they become good candidates for various commercial pplications. All these applications have already led to an important empirical control of these aterials, from their formation to their destruction. Besides this empirical background, which s widespread among the various specific applications, the basics of emulsions are certainly rogressing and we aim in this paper to give an overview of the most recent advances. We will articularly focus on interdroplet forces, reversible phase transitions and colloidal structures, onolayer adhesion and emulsion gels, coarsening and destruction and finally some stability riteria for double emulsions.