Ultrastable and Responsive Foams Based on 10-Hydroxystearic Acid Soap for Spore Decontamination

• Published in: Molecules (Basel, Switzerland) Vol. 28; no. 11; p. 4295
• Main Authors: Dari, Carolina, Cousin, Fabrice, Le Coeur, Clemence, Dubois, Thomas, Benezech, Thierry, Saint-Jalmes, Arnaud, Fameau, Anne-Laure
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24.05.2023; MDPI
• Subjects: Aqueous solutions; Castor oil; Chemical Sciences; Chirality; cleaning; Condensed Matter; Decontamination; Enantiomers; Fatty acids; foam; Foaming; Foams; hydroxy fatty acid; Hydroxyl groups; imbibition; Microorganisms; Microscopy; Monounsaturated fatty acids; Multiscale analysis; Neutron scattering; Oleic acid; Physics; Rheological properties; Rheology; Self-assembly; Soap; Soaps; Soft Condensed Matter; spore; Surface active agents; Surface tension; Surfactants; X-ray scattering; France; cleaning; self-assembly; hydroxy fatty acid; imbibition; spore; foam
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules28114295

Currently, there is renewed interest in using fatty acid soaps as surfactants. Hydroxylated fatty acids are specific fatty acids with a hydroxyl group in the alkyl chain, giving rise to chirality and specific surfactant properties. The most famous hydroxylated fatty acid is 12-hydroxystearic acid (12-HSA), which is widely used in industry and comes from castor oil. A very similar and new hydroxylated fatty acid, 10-hydroxystearic acid (10-HSA), can be easily obtained from oleic acid by using microorganisms. Here, we studied for the first time the self-assembly and foaming properties of R-10-HSA soap in an aqueous solution. A multiscale approach was used by combining microscopy techniques, small-angle neutron scattering, wide-angle X-ray scattering, rheology experiments, and surface tension measurements as a function of temperature. The behavior of R-10-HSA was systematically compared with that of 12-HSA soap. Although multilamellar micron-sized tubes were observed for both R-10-HSA and 12-HSA, the structure of the self-assemblies at the nanoscale was different, which is probably due to the fact that the 12-HSA solutions were racemic mixtures, while the 10-HSA solutions were obtained from a pure R enantiomer. We also demonstrated that stable foams based on R-10-HSA soap can be used for cleaning applications, by studying spore removal on model surfaces in static conditions via foam imbibition.