SPONTANEOUS FORMATION OF REVERSE VESICLES

It was found that reverse vesicles are formed in a sucrose monoalkanoa te/hexaethylene glycol hexadecyl ether (R16EO6)/hydrocarbon system in the absence of water. In the ternary system, a lamellar phase is forme d in the sucrose alkanoate-rich region, whereas an isotropic liquid ph ase, containing reverse micelles, appears in the R16EO6 region. The ag gregate shape depends on the sucrose alkanoate-to-R16EO6 ratio in the surfactant film, and a transition from reverse micelles to planar bila yers occurs with increasing content of sucrose alkanoate. Vesicles for m in the two-phase region where a lamellar phase coexists with oil, co ntaining solubilized R16EO6. Due to the high oil solubility of the R16 EO6 surfactant, this coexistence region can be reached by diluting the reverse micellar phase with oil. Hence, a transition from reverse mic elles to reverse vesicles can be generated by a simple oil dilution. T his system displays strong analogies to the aqueous systems composed o f a highly water soluble amphiphile, i.e., a bile salt, in addition to water and a lamellar-forming lipid, such as lecithin.