2020/04/06 by Vicente Domínguez-Arca, Domínguez-Arca, Vicente, Juan Sabín +7
Chemistry · Materials Science · #Surfactants and Colloidal Systems #Electrostatics and Colloid Interactions #Polymer Surface Interaction Studies
paper · pdf · doi:10.48550/arxiv.2004.02573
Self-assembly structures of gemini surfactants are characterized, among\nothers, for their low CMC. This characteristic could be due to great\nhydrophobic parts in their molecular structures. That availability could imply\ngreat stability of self-assembly structures or monolayers absorbed in an\ninterface. The micellization behavior of two cationic gemini surfactants,\n\α,\ω-bis(S-alkyl dimethylammonium) alkane bromides, were studied\nby a modelization of dynamic surface tension (DST) experimental data and\nisothermal titration calorimetry (ITC) measurements. The adsorption data at the\nair/water interface was taken through the analysis of the profile changes of a\npendant drop. The thermodynamic characterization of the micellization process\nof the gemini surfactants was carried out using ITC. A model based on the\nFrumkin adsorption isotherm and the Ward-Tordai diffusion equation was\ndeveloped to obtain the characteristic parameters of the adsorption without the\nneed of using the Gibbs adsorption equation. Positive values of lateral\ninteraction show good stability of the adsorbed monolayer. The ITC data were\nanalyzed following a novel protocol based on the identification of the\ndifferent energetic contributions and regimens observed in the titration\nenthalpograms from demicellization processes. The presence of exothermic peaks\nwould explain the low values of CMC.\n