Complex emulsions: tuning the chemical formulation to trigger transfer, adsorption and gelification

Emulsions are dispersions of one liquid in another (usually oil in water), stabilized by chemical species adsorbed at the interfaces between the two liquids (usually surfactants). For such a simple emulsion, the volume fraction of the dispersed phase is a crucial parameter, which sets many macroscopic properties (like its rheology). 
In this talk, I will present a few examples showing how it is easily possible to obtain emulsions with non-standard properties, exhibiting novel structures and viscoelasticities, which can no longer be simply rescaled by the volume fraction. 
In practice, we obtain these new behaviors by varying the chemical composition, the pH and the temperature, in order to both tune the interfacial and bulk rheological properties, to trigger transfer at interfaces, and to induce bulk gelification. In that respect, initially dilute emulsions developing a gel-like texture, double-emulsions spontaneously obtained and the mechanical stiffening of gelified emulsions will be discussed. 
Various characterization techniques, from those providing us with the microscopic self-assembled structures to macroscopic rheometry, will allow us to identify the origins of these behaviors. 
All together, these examples will highlight the major role of mechanisms occurring at the liquid-liquid interfaces in the macroscopic properties of an emulsion.