Solubilization of n-alkylbenzenes into gemini surfactant micelles in aqueous medium

The partitioning of primary alcohols into the aggregates of gemini amphiphiles determined from diffusion NMR experiments

The partition constants (p-values) of primary alcohols in solutions containing aggregates of symmetric gemini surfactants of the family N,N'-dimethyl, N-dialkyl-α,ω-alkanediammonium dibromide (m-s-m = symmetric gemini surfactants) have been computed from the measured values of their diffusion coefficients obtained from NMR-diffusion experiments. From the p-values, both mole-fraction and concentration-based partition coefficients and Gibbs energies of transfer for the alcohols from the bulk D2O phase to the gemini aggregate phase have been calculated. As expected, the Gibbs energy of transfer decreased linearly with an increase in the alcohol carbon length for each of the primary alcohol/gemini amphiphile series studied. The Gibbs transfer energy increment per CH2 for the alcohols was consistent for all the alcohol/gemini amphiphile series and was in excellent agreement with the values measured for the same primary alcohol series in conventional single-headed, single-tailed surfactants. Surprisingly, the partition coefficients of the alcohols in the symmetric gemini aggregates exhibited little, if any, dependence on the spacer length of the gemini amphiphiles and were remarkably consistent as the length of the main surfactant chain increased at constant spacer length. When these results are compared to the partition coefficients of the same alcohols in corresponding monomeric surfactants, we observe little difference in the thermodynamic driving forces governing the transfer of alcohols from water to the aggregates of either monomeric or symmetric gemini surfactants.

Solubilization of Progesterone and its Derivatives into Gemini Surfactant Solutions

The solubilization of poorly water-soluble progesterone derivatives into micelles of a gemini surfactant was investigated in an aqueous medium. The aqueous solubility at different temperatures was determined spectroscopically using an ultraviolet visible light spectrophotometer. Thermodynamic parameters for the solubilization were calculated under the basis of the solubility change against temperature. The solubility of progesterone was quite low and remained constant below the critical micelle concentration (cmc) of the surfactant. On the other hand, the solubility increased considerably with increasing surfactant concentration above the cmc. It was suggested that the solubilizates were located in the vicinity of polar regions of micelles.

Ion-selective molecular inclusion of organic dyes into pH-responsive gel assemblies of zwitterionic surfactants

The pH-Responsive sol–gel transition of a surfactant gel took place along with ion-selective capture and release of dye molecules.

Self-Assembly and Rheological Properties of a Pseudogemini Surfactant Formed in a Salt-Free Catanionic Surfactant Mixture in Water

The surface and bulk properties of bola-type dicarboxylic acid (sebacic acid, SA) and zwitterionic surfactant tetradecyldimethylamine oxide (C14DMAO) mixtures in aqueous solutions were studied. Surface tension measurements indicate a pronounced synergistic effect between SA and C14DMAO. In bulk aqueous solutions, rich phase behavior was observed with a varied SA-to-C14DMAO ratio (ρ) and a total surfactant concentration. Typically at ρ = 0.5, a novel pseudogemini surfactant (C14-S-C14) forms, driven by electrostatic interaction and hydrogen bonding. The C14-S-C14/H2O system exhibits rich phase behavior induced by the transition of aggregates. With increasing concentration of C14-S-C14, one can observe a viscous L1 phase, an L1/Lα two-phase region where a birefringent Lα phase is on the top of an L1 phase, a single Lα phase, and finally a mixture of an Lα phase and a precipitate. Microstructures formed in the Lα phases were determined by freeze-fracture transmission electron microscopy (FF-TEM) and cryogenic-transmission electron microscopy (cryo-TEM) observations. Polymorphic aggregation behavior was observed with the formation of a variety of bilayer structures including unilamellar vesicles, onions, and open and hyperbranched bilayers. Rheological measurements showed that the Lα phases are viscoelastic and sensitive to temperature where a quick loss of viscoelasticity was observed at elevated temperature.

Basic polymerized imidazolide-based ionic liquid: an efficient catalyst for aqueous Knoevenagel condensation

A novel basic polymerized ionic liquid (BPIL) with intensive base sites and high surface activity was synthesized and characterized by IR, ¹H NMR and ESI-MS. The BPIL was used as an efficient catalyst for aqueous Knoevenagel condensations.