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Aggregation Characteristics of Biobased Anionic Surfactant, Hydroxy Alkane Sulfonate in Aqueous CaCl2Solutions: Vesicle and Supported Bilayer Formation

Authors :
Sugahara, Tadashi
Ichihashi, Haruna
Tsumura, Kana
Hara, Teruyuki
Miyazaki, Atsushi
Sakai, Takaya
Source :
Langmuir; October 2024, Vol. 40 Issue: 41 p21719-21727, 9p
Publication Year :
2024

Abstract

Vesicles are known to spontaneously adsorb onto solid–liquid interfaces and to form supported bilayers in aqueous solution. Cationic surfactants have typically been used to generate supported bilayers because solid surfaces in water are often negatively charged. The present study investigated the aggregation behavior of an anionic surfactant, hydroxy alkane sulfonate having a C18 alkyl chain (C18HAS) in aqueous CaCl2solutions. These assessments were performed by acquiring data related to equilibrium surface tension, the solubilization of an oil-soluble dye, UV–visible transmittance, pyrene fluorescence and dynamic light scattering together with freeze-fracture transmission electron microscopy observations. The results suggest that C18HAS can form vesicles in aqueous CaCl2solutions under certain surfactant concentrations. Specifically, this aggregation behavior is greatly affected by C18HAS/CaCl2molar ratio. At the C18HAS/CaCl2molar ratio is less than an equivalence point (that is, less than 2:1), phase separation occurs with the formation of a vesicle above solubility limit of the C18HAS Ca salt. On the other hand, in the case that the C18HAS/CaCl2molar ratio is above an equivalence point (that is, above 2:1), the Na salt of C18HAS forms micelles above the critical micelle concentration (cmc), causing solubilization of vesicles. Analyses by high-speed atomic force microscopy demonstrated that the C18HAS vesicles can spontaneously form a supported bilayer on a negatively charged mica surfaces, similar to the behavior of cationic surfactant vesicles, even though C18HAS is an anionic surfactant. These results suggest that C18HAS could serve as a detergent component but also as a surface modifier when the C18HAS/CaCl2molar ratio is optimized.

Details

Language :
English
ISSN :
07437463 and 15205827
Volume :
40
Issue :
41
Database :
Supplemental Index
Journal :
Langmuir
Publication Type :
Periodical
Accession number :
ejs67548823
Full Text :
https://doi.org/10.1021/acs.langmuir.4c02786