Current phenomenological know-how and modeling of emulsion inversion

This paper encompasses classic trends as well as recent advances in the understanding of emulsion inversion phenomena. The generalized formulation issue is first discussed from hydrophilic-lipophilic balance to the most recent concepts. The so-called standard inversion line on the formulation-composition map exhibits several branches, referred to as transitional and catastrophic inversions, that bound normal and abnormal emulsion regions. Dynamic inversion is also discussed with its hysteresis zones, where both types of emulsions may be attained, depending upon the system's previous history of the formulation-composition map. Recent findings are reported concerning the effect of variables with practical relevance (i.e., stirring energy, viscosity of phases, surfactant concentration, and partitioning) on the standard and dynamic inversion patterns. State-of-the-art emulsion inversion modeling is briefly discussed.