Self-assembly of quaternary ammonium gemini surfactants in cyclohexane upon reinforcement by simple counterions.

The quaternary ammonium gemini surfactants 12--12 ( = 2, 6, and 10) can produce homogeneous cyclohexane solutions with the assistance of salts, sodium benzoate (NaBez), sodium salicylate (NaSal), or sodium 2-bromoethanesulphonate (NaBres). In these samples, 12--12/salt formed aggregates and their structures were assigned by SAXS measurements together with POM observations. Among the three salts, both NaBez and NaBres had similar effects on assisting aggregate formation, but NaSal favoured the generation of aggregates of 12--12 with lower interface curvature.

[Study on extraction process of available components of tea].

Objective: To investigate the optimum ethanol extraction process conditions for the available components in the tea - Catechines (CT) including Epigallo catechin gallate (EGCG) and Caffeine (CF).

Methods: The content of EGCG, CT and CF, extraction rate, DPPH * Free radical scavenging capacity were chosen as the assessment indexes. With the alcohol ratio (A), solid-liquid ratio (B) and reflux time (C) as investigation factors, the optimum ethanol extraction process of the available components from tea was determined by L9 (3(4)) orthogonal experimental design.

Dilution method study on the interfacial composition and structural parameters of water/C12-EOx-C12.2Br/n-hexanol/n-heptane microemulsions: effect of the oxyethylene groups in the spacer.

The interfacial composition and the structure of the water/C(12)-EO(x)-C(12).2Br/n-hexanol/n-heptane microemulsion have been investigated by the dilution method. The results showed that C(12)-EO(x)-C(12).

[Aggregation number determination of gemini anionic surfactant micelle by intrinsic fluorescence quenching].

The p-phendioxyl base in the spacer of gemini surfactant C11pPHCNa emits fluorescence under exciting. When the gemini concentration is over 0.45 mmol x L(-1), the topological structure of the excitation spectra yields various changes resulting in them being significantly different from the corresponding absorption spectra.

Solubilization of pyrene in aqueous micellar solutions of gemini surfactants C12-s-C12.2Br.

Solubilization of pyrene in aqueous micellar solutions of quaternary ammonium gemini surfactants C(12)-s-C(12).2Br has been examined by UV spectra and steady fluorescence spectra at 30 degrees C. The results showed that pyrene molecules were incorporated in the palisade layers of the micelles and interacted with the quarterary ammonium head groups through cation-pi interaction, resulting in red shift of the UV absorption spectrum.

Aggregation of quaternary ammonium gemini surfactants C12-s-C12.2Br in n-heptane/n-hexanol solution: effect of the spacer chains on the critical reverse micelle concentrations.

The critical reverse micelle concentrations of C(12)-s-C(12).2Br (s=2,3,4,5,6,8,12) in n-heptane/n-hexanol solutions, cmc(I)s, have been determined by absorption spectrum method using iodine as probe. The values of cmc(I)s are smaller than those of the critical micelle concentrations (cmc(aq)s) in aqueous solution and reach a maximum at s=4, which is similar to the variation of cmc(aq) with s.

Interfacial composition and structural parameters of water/C12-s-C12 x 2Br/n-hexanol/n-heptane microemulsions studied by the dilution method.

The interfacial composition of the stable water/C12-s-C12 x 2Br/n-hexanol/n-heptane microemulsions has been studied in detail by dilution method. The results showed a marked maximum amount of the n-hexanol populating on the surfaces of droplets (represented as a = n(a)i/n(s), where n(a)i and n(s) are respectively the moles of n-hexanol and gemini surfactant on the surface of droplets) with increasing water content. At a constant level of water addition (the molar ratio of water to surfactant W0 = 20), a decreased with increasing the spacer length in the C12-s-C12 x 2Br molecule.

Adsorption dynamics of binary mixture of Gemini surfactant and opposite-charged conventional surfactant in aqueous solution.

The maximum bubble pressure technique has been used to study the adsorption kinetics of binary mixtures of an anionic Gemini surfactant C9pPHCNa with a cationic conventional surfactant C10TABr in aqueous solutions. The dynamic surface tension data were analyzed using the revised Ward and Tordai equations as well as the micelle dissociation kinetic model suggested by Joos et al. The apparent diffusion coefficient Da below the cmc, the adsorption barrier epsilona and the micelle dissociation constant kmic were obtained.