title: Supramolecular "Big Bang" in a Single-Ionic Surfactant/Water System Driven by Electrostatic Repulsion: From Vesicles to Micelles.
abstract: In aqueous solution, dimethyldi-n-octylammonium chloride, [DiC8][Cl], spontaneously forms dimers at low concentrations (1-10 mM) to decrease the strength of the hydrophobic-water contact. Dimers represent ideal building blocks for the abrupt edification of vesicles at 10 mM. These vesicles are fully characterized by dynamic and static light scattering, self-diffusion nuclear magnetic resonance, and freeze-fracture transmission electron microscopy. An increase in concentration leads to electrostatic repulsion between vesicles that explode into small micelles at 30 mM. These transitions are detected by means of surface tension, conductivity, and solubility of hydrophobic solutes as well as by isothermal titration microcalorimetry. These unusual supramolecular transitions emerge from the surfactant chemical structure that combines two contradictory features: (i) the double-chain structure tending to form low planar aggregates with low water solubility and (ii) the relatively short chains giving high hydrophilicity. The well-balanced hydrophilic-hydrophobic character of [DiC8][Cl] is then believed to be at the origin of the unusual supramolecular sequence offering new opportunities for drug delivery systems.
authors.affiliation: Univ. Lille , UMR 8181-UCCS-Unité de Catalyse et Chimie du Solide, F-59000 Lille, France.
authors.forename: Loïc
authors.identifier: 0000-0002-9206-3863
authors.initials: L
authors.lastname: Leclercq
authors.affiliation: Institut de Chimie Séparative de Marcoule, UMR 5257, CEA/CNRS/UM2/ENSCM , BP 17171 CEA Marcoule, F-30207 Bagnols-sur-Cèze, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bauduin
authors.affiliation: Univ. Lille , UMR 8181-UCCS-Unité de Catalyse et Chimie du Solide, F-59000 Lille, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Nardello-Rataj