TY - JOUR A1 - Prevost, Sylvain A1 - Wattebled, Laurent A1 - Laschewsky, André A1 - Gradzielski, Michael T1 - Formation of monodisperse charged vesicles in mixtures of cationic gemini surfactants and anionic SDS JF - Langmuir N2 - 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 degrees 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. Y1 - 2011 U6 - https://doi.org/10.1021/la103976p SN - 0743-7463 VL - 27 IS - 2 SP - 582 EP - 591 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wattebled, Laurent A1 - Laschewsky, André A1 - Moussa, Alain A1 - Habib-Jiwan, Jean-Louis T1 - Aggregation numbers of cationic oligomeric surfactants : A time-resolved fluorescence quenching study N2 - The micelle aggregation numbers (N-agg) of several series of cationic oligomeric surfactants were determined by time-resolved fluorescence quenching (TRFQ) experiments, using advantageously 9,10-dimethylanthracene as fluorophore. The study comprises six dimeric ("gemini"), three trimeric, and two tetrameric surfactants, which are quaternary ammonium chlorides, with medium length spacer groups (C-3-C-6) separating the individual surfactant fragments. Two standard cationic surfactants served as references. The number of hydrophobic chains making up a micellar core is relatively low for the oligomeric surfactants, the spacer length playing an important role. For the dimers, the number decreases from 32 to 21 with increasing spacer length. These numbers decrease further with increasing degree of oligomerization down to values of about 15. As for many conventional ionic surfactants, the micelles of all oligomers studied grow only slightly with the concentration, and they remain in the regime of small micelles up to concentrations of at least 3 wt %. Y1 - 2006 UR - http://pubs.acs.org/doi/full/10.1021/la052414h U6 - https://doi.org/10.1021/La052414h ER - TY - JOUR A1 - Laschewsky, André A1 - Lunkenheimer, K. A1 - Rakotoaly, R. H. A1 - Wattebled, Laurent T1 - Spacer effects in dimeric cationic surfactants N2 - A series of dimeric cationic surfactants (gemini surfactants), which have spacer groups of varying length and flexibility, was synthesized. The series is derived from the parent compounds dodecyltrimethylammonium chloride or benzyldodecyldimethylammonium chloride. Characteristic surfactant properties of the dimeric ammonium compounds such as surface activity, micellization, viscosity effects, foaming, and solubilization, were studied with respect to the influence of the spacer group on the surfactant. For all properties, the influence of the length of the spacer group was predominant though the chemical nature of the spacer cannot be neglected Y1 - 2005 SN - 0303-402X ER - TY - JOUR A1 - Laschewsky, André A1 - Wattebled, Laurent A1 - Arotcarena, Michel A1 - Habib-Jiwan, Jean-Louis A1 - Rakotoaly, R. H. T1 - Synthesis and properties of cationic oligomeric surfactants N2 - Three series of new oligomeric cationic surfactants were synthesized. These amphiphiles are trimeric and tetrameric oligomeric quaternary ammonium chlorides, with spacer groups of different lengths separating the individual surfactant fragments. The properties of the compounds, such as Krafft temperatures, surface activity, micellization, viscosifying effects, foaming and solubilizing capacity, are studied. The influence of the degree of oligomerization and of the spacer group on the surfactant properties is discussed, in comparison with the analogous standard monomeric and dimeric ("gemini") surfactants. Typically, the evolution of the properties observed from standard to dimeric surfactants progresses with the trimers and tetramers, resulting for instance in extremely low critical micellization concentrations Y1 - 2005 SN - 0743-7463 ER -