title: Self-assembly of myristic acid in the presence of choline hydroxide: effect of molar ratio and temperature.
abstract: Salt-free catanionic systems based on fatty acids exhibit a broad polymorphism by simply tuning the molar ratio between the two components. For fatty acid combined with organic amino counter-ions, very few data are available on the phase behavior obtained as a function of the molar ratio between the counter-ion and the fatty acid. We investigated the choline hydroxide/myristic acid system by varying the molar ratio, R=n(choline hydroxide)/n(myristic acid), and the temperature. Myristic acid ionization state was determined by coupling pH, conductivity and infra-red spectroscopy measurements. Self-assemblies were characterized by small angle neutron scattering and microscopy experiments. Self-assembly thermal behavior was investigated by differential scanning calorimetry, wide angle X-ray scattering and nuclear magnetic resonance. For R<1, ionized and protonated myristic acid molecules coexisted leading to the formation of facetted self-assemblies and lamellar phases. The melting process between the gel and the fluid state of these bilayers induced a structural change from facetted or lamellar objects to spherical vesicles. For R>1, myristic acid molecules were ionized and formed spherical micelles. Our study highlights that both R and temperature are two key parameters to finely control the self-assembly structure formed by myristic acid in the presence of choline hydroxide.
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, F-44316 Nantes, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Arnould
authors.affiliation: Grupo de Biocoloides, Instituto de Tecnología de Alimentos, Universidad Nacional del Litoral, 1 de Mayo 3250 (3000), Santa Fe, Argentina.
authors.forename: Adrian A
authors.initials: AA
authors.lastname: Perez
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, F-44316 Nantes, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Gaillard
authors.affiliation: Biologie et Pathologie du Fruit, UMR 1332, INRA, Centre de Bordeaux, 33883 Villenave d'Ornon, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Douliez
authors.affiliation: Laboratoire Léon Brillouin, CEA-CNRS, CEA Saclay, 91191 Gif sur Yvette Cedex, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Cousin
authors.affiliation: Grupo de Biocoloides, Instituto de Tecnología de Alimentos, Universidad Nacional del Litoral, 1 de Mayo 3250 (3000), Santa Fe, Argentina.
authors.forename: Liliana G
authors.initials: LG
authors.lastname: Santiago
authors.affiliation: Institut de Chimie Séparative de Marcoule (ICSM), UMR 5257, CEA-CNRS-Université Montpellier 2-ENSCM, F-30207 Bagnols-sur-Cèze Cedex, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Zemb
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, F-44316 Nantes, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Anton
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, F-44316 Nantes, France. Electronic address: anne-laure.fameau@nantes.inra.fr.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Fameau
mesh_terms: D002794:Choline / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D019814:Myristic Acid / Q000737:chemistry*; D044367:Phase Transition; D013696:Temperature
chemical_list: D007477:Ions; D008051:Lipid Bilayers; D019814:Myristic Acid; D002794:Choline
keywords: Catanionic; Counter-ion; Fatty acid; Molar ratio; Self-assembly