title: Formation of monodisperse charged vesicles in mixtures of cationic gemini surfactants and anionic SDS.
abstract: The aggregation behavior of catanionics formed by the mixture of cationic geminis derived from dodecyltrimethylammonium chloride (DTAC) and anionic sodium dodecylsulfate (SDS) was studied by means of phase studies and comprehensive small-angle neutron scattering (SANS) experiments at 25 °C and 50 mM overall concentration. The results are compared to those for the previously studied SDS + DTAC system. Various gemini spacers of different natures and geometries were used, but all of them had similar lengths: an ethoxy bridge, a double bond, and an aromatic ring binding the two DTACs in three different substitutions (ortho, meta, and para). SANS and SAXS data analysis indicates that the spacer has no large effect on the spheroidal micelles of pure surfactants formed at low concentration in water; however, specific effects appear with the addition of electrolytes. Microstructures formed in the catanionic mixtures are rather strongly dependent on the nature of the spacer. The most important finding is that for the hydrophilic, flexible ethoxy bridge, monodisperse vesicles with a fixed anionic/cationic charge ratio (depending only on the surfactant in excess) are formed. Furthermore, the composition of these vesicles shows that strongly charged aggregates are formed. This study therefore provides new opportunities for developing tailor-made gemini surfactants that allow for the fine tuning of catanionic structures.
authors.affiliation: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, Sekr. TC7, D-10623 Berlin, Germany. prevost.sylvain@gmail.com
authors.forename: Sylvain
authors.initials: S
authors.lastname: Prévost
authors.forename: Laurent
authors.initials: L
authors.lastname: Wattebled
authors.forename: André
authors.initials: A
authors.lastname: Laschewsky
authors.forename: Michael
authors.initials: M
authors.lastname: Gradzielski
mesh_terms: D000838:Anions / Q000737:chemistry; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: C411462:1,25-dihydroxy-21-(3-hydroxy-3-methylbutyl)vitamin D(3); D000838:Anions; D002412:Cations; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D002117:Calcitriol; C022806:dodecyltrimethylammonium