Microemulsions Winsor classification

Fig. 3.2 Ternary phase diagram (schematic) of water-oil-surfactant mixtures showing Winsor classification and probable internal structures Lj, one-phase region of normal micelles or oil-in-water (o/w) microemulsion L2. reverse micelles or water-in-oil (w/o) microemulsions D, anisotropic lamellar liquid crystalline phase. Other symbols fie microemulsion O oil W water...

The Winsor microemulsion classification system distinguishes among three different types based on their phase behaviour ... 

According to Winsor s classification, we have four types of microemulsion systems Winsor I (WI), Winsor II (WII), Winsor III (Will), and Winsor IV (WIV). The ion conductance of WI (o/w system) is reasonably high just like aqueous solution, where water is the dispersion medium whereas the conductance in WII (w/o system) is very low, where the dispersion medium is oil. In Will systems, where both o/w and w/o dispersions are simultaneously present... 

Another important phase classification that can often be found in literature has been introduced by Winsor (Winsor 1948), who found four general types of phase equilibria. A Winsor type IV phase corresponds to classical single phase microemulsions consistent with Hoar s Schulman s definition (Hoar Schulman 1943). A Winsor type I system denotes two phases in equilibrium, an o/w structure and an almost pure oil upper phase. On the contrary, in a Winsor type II system an aqueous phase containing surfactant is in equilibrium with an w/ o microemulsion in the upper phase. Finally, Winsor type III structures equal a three-phase system consisting of a surfactant poor water phase, a bicontinuous middle phase, and an upper almost pure oil phase. 

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