Catanionic Gels Based on Cholic Acid Derivatives

In this paper, the preparation and characterization of an anionic and a cationic surfactant obtained by chemical modifications of a natural bile acid (cholic acid) are reported. The bile acid was modified by introducing a diamine or a dicarboxylic aromatic residue on the lateral chain. The pure cati...

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Bibliographic Details
Published in:Langmuir 2013-10, Vol.29 (40), p.12342-12351
Main Authors: di Gregorio, M. Chiara, Pavel, N. Viorel, Miragaya, Javier, Jover, Aida, Meijide, Francisco, Vázquez Tato, José, Soto Tellini, Victor H, Galantini, Luciano
Format: Article
Language:English
Subjects:
Cations - chemistry
Chemistry
Cholic Acid - chemistry
Colloidal gels. Colloidal sols
Colloidal state and disperse state
Exact sciences and technology
Gels - chemistry
General and physical chemistry
Micelles. Thin films
Surface-Active Agents - chemistry
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Summary:In this paper, the preparation and characterization of an anionic and a cationic surfactant obtained by chemical modifications of a natural bile acid (cholic acid) are reported. The bile acid was modified by introducing a diamine or a dicarboxylic aromatic residue on the lateral chain. The pure cationic surfactant self-assembles in a network of fibers with a cross-section gyration radius of about 15.1 Å, providing hydrogels with a pH-dependent compactness. On the other hand, the anionic molecule gives rise to prolate ellipsoid micelles. Homogeneous catanionic mixtures have also been obtained, with molar fraction of each surfactant ranging from 0.125 to 0.875. At total surfactant concentration of 0.05% (w/v), the mixtures form gels of fibrils partially arranged in secondary twisted superstructures. Comparison of this concentration with the minimum gelation concentration of the pure cationic derivative (0.16% w/v) suggests that, in the mixtures, the presence of the electrostatic component in self-assembly of the molecules allows the formation of gels starting from more dilute samples. In view of these achievements, this work suggests that catanionic mixtures can be exploited to enhance the efficiency of gelators.
ISSN:0743-7463
1520-5827
DOI:10.1021/la402602d