*2.1.3 Surfactants*

They are usually employed in order to decrease the surface tension as well as the interfacial tension. Since, they contain both the lipophilic as well as hydrophilic character; they have the affinity towards both the polar and the non-polar phase. When the aqueous phase is more compared to the oily phase, then the interface between the oil and aqueous phase will curve spontaneously towards the water leading to the formation of oil in water structure. Whereas, when the lipophilic group is more bulky than that of aqueous phase, then the interface will curve towards the opposite direction leading to water in oil microemulsion [15]. In brief the different types of surfactants used in microemulsion are given in **Table 2**. While coming to the type of surfactant, they can be divided into the following:

