Formation of monodisperse charged vesicles in mixtures of cationic gemini surfactants and anionic SDS.

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).

Effects of organic salt additives on the behavior of dimeric ("gemini") surfactants in aqueous solution.

The effects of a series of aromatic anions, so-called hydrotropes, on characteristic solution properties of a family of ammonium gemini surfactants with dodecyl chains were explored. The stoichiometric addition of the organic salts to the geminis can result in clear solutions or in phase separation/precipitation, depending on the detailed nature of the added counterions and on the spacer group of the gemini surfactant. Many organic anions induce synergistic effects, strongly reducing the critical micellization concentration (cmc) and the surface tension at the cmc.

Effect of a new hydrophobically modified polyampholyte on the formation of inverse microemulsions and the preparation of gold nanoparticles.

A new regular polyampholyte, namely poly-(N,N-dially-N,N-dimethylammonium-alt-N-octyl-maleamic carboxylate), was synthesized by alternating free radical copolymerization. The influence of the added polymer on the range of the inverse micellar region (L(2) phase) of a SDS-based system was investigated. The phase behavior as well as conductivity measurements indicate that the polymer, which forms hydrophobic microdomains, is located more in the water core of the microemulsion droplets rather than at the interface of the surfactant film.

Aggregation numbers of cationic oligomeric surfactants: a time-resolved fluorescence quenching study.

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.

Synthesis and properties of cationic oligomeric surfactants.

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.