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 = ncholine hydroxide/nmyristic 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.
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https://hal.umontpellier.fr/hal-02118206
Contributeur : Xavier Le Goff <>
Soumis le : jeudi 2 mai 2019 - 22:33:25
Dernière modification le : mardi 23 juillet 2019 - 17:14:04

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Audrey Arnould, Adrian Perez, Cédric Gaillard, Jean-Paul Douliez, Fabrice Cousin, et al.. Self-assembly of myristic acid in the presence of choline hydroxide: Effect of molar ratio and temperature. Journal of Colloid and Interface Science, Elsevier, 2015, 445, pp.285-293. ⟨10.1016/j.jcis.2015.01.008⟩. ⟨hal-02118206⟩

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