Microstructures in aqueous solutions of hybrid fluorocarbon/hydrocarbon catanionic surfactants

Mixtures of new hybrid fluorocarbon/hydrocarbon catanionic sugar-based surfactants are prepared by an acid–base reaction between N-alkylamino-1-lactitols and fluorinated carboxylic or phosphinic acids, respectively. The presence of the sugar moiety allows the synthesis of water soluble catanionic mixtures in an equimolar ratio over a wide range of concentrations (0.1–50 mM). These catanionic salts are able to form spontaneously supramolecular assemblies in water. Dynamic light scattering is used to identify the aggregate size in water, whereas transmission electron microscopy is used to identify the morphology of the catanionic mixtures. Slight variation of the molecular structure (perfluorooctyl moiety or perfluorodecyl-moiety) can lead to marked differences in the shape of the molecular aggregates: vesicles or coiled membranes. Moreover, perfluorodecyl-derived catanionic mixtures show an original behaviour forming lamellar dispersions in water even at concentrations as low as 1 mM.