title: Self-assembly, foaming, and emulsifying properties of sodium alkyl carboxylate/guanidine hydrochloride aqueous mixtures.
abstract: Unsaturated fatty acids may be extracted from various agricultural resources and are widely used as soaps in the industry. However, there also exist a large variety of saturated and hydroxy fatty acids in nature, but their metal salts crystallize at room temperature in water, hampering their use in biological and chemical studies or for industrial applications. Addition of guanidine hydrochloride (GuHCl) to sodium salt of myristic acid has been shown to prevent its crystallization in water, forming stable flat bilayers at room temperature. Herein, we extend this finding to two other saturated fatty acids (palmitic and stearic acids) and two hydroxyl fatty acids (juniperic and 12 hydroxy stearic acids) and study more deeply (by using small angle neutron scattering) the supramolecular assemblies formed in both saturated and hydroxyl fatty acid systems. In addition, we take the advantage that crystallization no longer occurs at room temperature in the presence of GuHCl to study the foaming and emulsifying properties of those fatty acid dispersions. Briefly, our results show that all fatty acids, even juniperic acid, which is a bola lipid, are arranged in a bilayer structure that may be interdigitated. Depending on the nature of the fatty acid, the systems exhibit good foamability and foam stability (except for juniperic acid), and emulsion stability was good. Those findings should be of interest for using saturated long chain (and hydroxyl) fatty acids as surfactants for detergency or even materials chemistry.
authors.affiliation: UR1268, INRA Nantes, Biopolymères Interactions Assemblages, rue de la Géraudière, 44316 Nantes, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Fameau
authors.forename: Bérénice
authors.initials: B
authors.lastname: Houinsou-Houssou
authors.forename: Jorge Luis
authors.initials: JL
authors.lastname: Ventureira
authors.forename: Laurence
authors.initials: L
authors.lastname: Navailles
authors.forename: Frédéric
authors.initials: F
authors.lastname: Nallet
authors.forename: Bruno
authors.initials: B
authors.lastname: Novales
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Douliez
mesh_terms: D004655:Emulsions / Q000737:chemistry*; D005227:Fatty Acids / Q000737:chemistry*; D019791:Guanidine / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D019814:Myristic Acid / Q000737:chemistry; D019308:Palmitic Acid / Q000737:chemistry; D013229:Stearic Acids / Q000737:chemistry
chemical_list: D004655:Emulsions; D005227:Fatty Acids; D008051:Lipid Bilayers; D013229:Stearic Acids; D019814:Myristic Acid; D019308:Palmitic Acid; D019791:Guanidine