Elastic properties of monolayers of soluble surfactants at oil-brine interfaces

The microstructure of microemulsions and related systems diluted in surfactant is determined in a first approximation via the characteristics of the surfactant monolayer: the bending elastic modulus, K, the saddle splay modulus, (K) over bar and the spontaneous curvature C-0. The methods which were developed to measure these quantities in Winsor equilibrium (microemulsions or related systems in equilibrium with an excess of oil or brine) are discussed. Results concerning various surfactants are given and compared with the results obtained for similar systems with other techniques. It is also shown how these results explain the observed phase structures.