Lyotropic mesophases of a fluorinated surfactant with a short nonionic polar head in water

The phase behavior of a water-nonionic fluorinated surfactant C6F13C2H4SC2H 4(OC2H4)(2)OH system is reported here. Beyond a reverse micellar phase, thr ee other mesophases are found: a lamellar phase L-alpha, a bicontinuous cub ic domain V-2, and a sponge phase L-3 Its phase diagram is compared with hy drogenated ones. The characterization of these phases and the determination of their structural parameters are performed by SAXS experiments. The cubi c phase domain is divided into two cubic phases corresponding to the Ia3d a nd Pn3m structures. They both are described according to ICR and IPMS model s. The study of the structural parameters shows that the area per polar gro up stays constant and the hydrophobic surfactant part is unchanged in all t he liquid crystal domains. Epitaxial relationships between the phases are d iscussed.