Microemulsions: experimental aspects

The authors present experimental results on microemulsions made with water-alkane nonionic surfactant systems that confirm the close relationship between the maximum characteristic size in the microemulsion and the persistence length of the surfactant layer. The microemulsion structures are found with surfactants that form films of small bending elasticity. When the bending elasticity is too large, ordered lamellar phases are obtained. When it is too small, the surfactant film cannot form, and the medium is a structureless molecular mixture. This evolution is associated with a wetting transition.