Microemulsions are formed because ...
•The penalty for the apparent increase in free energy is compensated by the lowering of IFT to ultra low levels (10-2 –10-3mN/m)
•The work done in lowering IFT is achieved through a gain in system entropy ΔS due to the creation of a large number of sub-micron sized droplets
All this occurs when at molecular levels, surfactants form the most condensed interfacial film between oil and water