BENDING ELASTIC-MODULI OF THE SURFACTANT FILM AND PROPERTIES OF A WINSOR-II MICROEMULSION SYSTEM

The bending elastic modulus K and the Gaussian bending elastic modulus ($) over bar K of the surfactant film in a microemulsion system composed of sodium dodecyl sulfate (SDS), cyclohexane, water plus salt and two different. cosurfactants, pentanol and hexanol, are presented. K is deduced from ellipsometry at the planar surfactant film at the macroscopic oil-brine interface, while ($) over bar K is obtained from properties of Winsor II microemulsion equilibria. These properties involve the volume fraction dependence of the (mean) droplet size, polydispersity of the droplet radius and interfacial tensions between the planar microemulsion-brine interface. The values of the bending elastic moduli are compared with the global phase behavior of these systems;as reported recently (Kegel, W. K.; Lekkerkerker, H. N. W. J. Phys. Chem. 1993, 97, 11124).