Yan Cheng Zheng

Interaction Behavior Between an Amino Sulfonate Surfactant and Octylphenol Polyoxyethylene Ether (10) in Aqueous Solution

The micellization of binary mixtures of sodium dodecyl diamino sulfonate (C12AS) and nonionic octylphenol polyoxyethylene ether (10) (OP-10) was investigated in aqueous solution at a pH of about 6.0. Two techniques, UV–Vis spectroscopy using pyrene as a probe and surface tensiometry, were employed in this work to obtain information on the micellization behavior of the mixed C12AS/OP-10 system. The interaction parameters between the two components, activity coefficients in mixed micelles, compositions of mixed micelles, and thermodynamic parameters of micellization (calculated using Clint’s equation, Rubingh’s treatment based on regular solution theory, and Rodenas’s treatment considering the Gibbs–Duhem equation) were evaluated for this mixed surfactant system. The results show that the synergistic effect between C12AS and OP-10 in all mixed systems plays a vital role in the reduction of the overall critical micelle concentration (cmc) value in aqueous solution. In the process of micellization, both the steric effect of the head group and the charge density for C12AS affect the formation and stability of the mixed micelles, and the entry of a small amount of C12AS into the unconsolidated micelle of OP-10 is more favorable to the formation of the mixed micelle by promoting the reduction of the mixed micelle cmc value. Thermodynamic data show that micellization for the mixed C12AS/OP-10 system is both an enthalpy and entropy driven process.

Micellization behavior of the mixtures of amino sulfonate amphoteric surfactant and octadecyltrimethyl ammonium bromide in aqueous solution at 40 °C: a tensiometric study

In aqueous solution at 40xa0°C, the micellization behavior of the binary mixtures constituted by an amphoteric sodium n-dodecyl diamine sulfonate and a cationic octadecyltrimethyl ammonium bromide has been investigated by the tensiometric technology. The values of critical micelle concentration (cmc) were determined by surface tension measurement of aqueous solution. The experimental data were analyzed according to various mixing thermodynamic models within the framework of the pseudophase separation model. The values of mixed cmc have been predicted successfully by both the Rubingh’s and Rodenas’s treatments. Various parameters like the mixed cmc, interaction parameters between surfactants (β12), the compositions and activity coefficients in mixed micelles as well as thermodynamic properties have been determined using Lang, Rubingh, Rodenas, and Rosen approach. Over the entire composition range investigated, the mixed micelle formation, non-ideal or ideal mixing, and synergistic effect or antagonism are explained by the electrostatic interaction between ionic headgroups of surfactants and the steric effect of surfactant. Thermodynamic parameters favor the process of micellization which is found to be entropy-driven.

Mixed micellization of binary mixture of amino sulfonate amphoteric surfactant with octadecyltrimethyl ammonium bromide in water/isopropanol solution: Comparison with that in aqueous solution

Abstract The micellization behavior of the mixed system of amphoteric sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) and cationic octadecyltrimethyl ammonium bromide (OTAB) in water/isopropanol (abbr. IPA, 20 g·L−1) solution at 40u2009°C was investigated using both the tensiometry and the conductometry. According to the regular solution theory, pseudophase separation model and other thermodynamic models (including the Rubingh’s model, the Rodenas’s model, Lange’s model, etc.), some parameters were estimated to achieve a full understanding of their aggregation behaviors. For all the mixtures of C12AS/OTAB, the mixed critical micelle concentration and the composition of C12AS in mixed micelle have deviations from their ideal cases, indicating a non-ideal mixing. The presence of cosolvent IPA produces the changes in the composition in mixed micelle and the optimum mixing ratio which can obtain a maximum synergism. The interaction parameter indicates an attractive interaction between two surfactants. Thermodynamic parameters show that the mixed micellization is an entropically spontaneous process and the presence of IPA seemingly reduces the entropy contribution to the formation of mixed micelle. The above behaviors can be explained rationally by the hydrophobic effect, the steric effect and the attractive interaction between two surfactants. These findings are useful for optimizing the composition of mixed surfactant systems and understanding the interaction behavior between surfactant molecules to further achieve more effective and economical formulations. Graphical Abstract