title: Multiscale structural characterizations of fatty acid multilayered tubes with a temperature-tunable diameter.
abstract: It is known that 12-hydroxystearic acid coupled via ion-pairing with a counterion, such as ethanolamine, self-assembles into supramolecular multilayer tubes that exhibit a peculiar temperature-tunable diameter variation. At a given temperature threshold (T(Ø↑)), there is a large increase of the tube diameter by almost a factor of 10. We investigate here the nature of the counterion on the self-assembly of such tubes and the variation of their diameter with the temperature. Eight different counterions are used to produce tubes via ion-pairing with 12-hydroxystearic acid. We systematically measure structural parameters at different scales coupling phase contrast microscopy and small-angle neutron scattering (SANS), in combination with thermodynamic studies using differential scanning calorimetry (DSC). The temperature T(Ø↑) is found to depend sensitively on the nature of the counterion. One could not identify any DSC peak associated with the diameter variation. However, a detailed line-shape analysis of the SANS spectra reveals that a significant softening of the elastic properties of the multilayer tube walls occurs at T(Ø↑), for all counterions investigated. Depending on both the temperature and the nature of the counterion, the interlayer spacing in the multilayered structure (respectively, the bilayer thickness) varies in a range from 240 to 440 Å (respectively, from 22 to 42 Å), but those variations appear not to be related to T(Ø↑). Altogether, our results show that the variation of the diameter is correlated to the nature of the counterion and to the elastic properties of the bilayer stack.
authors.affiliation: UR1268 Biopolymères Interactions Assemblages Inra, rue de la Géraudière, 44316 Nantes, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Fameau
authors.forename: Fabrice
authors.initials: F
authors.lastname: Cousin
authors.forename: Laurence
authors.initials: L
authors.lastname: Navailles
authors.forename: Frédéric
authors.initials: F
authors.lastname: Nallet
authors.forename: François
authors.initials: F
authors.lastname: Boué
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Douliez
mesh_terms: D000588:Amines / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D008853:Microscopy; D033363:Neutron Diffraction; D044367:Phase Transition; D053838:Scattering, Small Angle; D013229:Stearic Acids / Q000737:chemistry*; D013696:Temperature
chemical_list: C539357:12-hydroxy stearic acid; D000588:Amines; D013229:Stearic Acids