Supra-aggregates

Mixtures of oil (isooctane), water, and a double-chained ionic surfactant, Cu(AOT)(2) [copper(II) bis(2-ethylhexyl)sulfosuccinate] form equilibrium ph ases consisting of spontaneous emulsions thermodynamically stable systems. The experimental conditions are such that the head polar group of the surfa ctant is totally hydrated. The emulsion droplets are comprised of supra agg regates, lamellar spherulites in which interior and exterior are bicontinuo us microemulsions. The microstructures and component ratios can be predicte d from elementary considerations that require only the notion of local and global packing constraints. The phenomenon of supra aggregation, microphase s within any topologically closed container, in equilibrium with an externa l phase, appears quite general. The results throw some light on the meaning of 'phase' in mesostructured fluids. (C) 2001 Elsevier Science B.V. All ri ghts reserved.