Aggregate transition from nanodisks to equilibrium among vesicles and disks

A dilute, salt-free cationic/anionic/nonionic surfactant system was prepared. The cationic surfactant is derived from a zwitterionic tetradecyldimethylamine oxide (C₁₄DMAO) charged by a strongly acidic anionic surfactant Texapon N₇₀-H [CH₃(CH₂), ₁₁(CH₂CH₂O)_2.5SO₃H]. The aggregate transition from nanodisks to the coexistence of disks and unilamellar vesicles to the equilibrium among disks, unilamellar vesicles, and multilamellar vesicles with polydisperse size distributions was observed by freeze-fracture transmission electron microscopy (FF-TEM) in the dilute, salt-free cationic/anionic/nonionic surfactant mixtures. At equilibrium, dynamic laser light scattering (DLLS) measurements show three peaks, which are attributed to the nanodisks, unilamellar vesicles, and multilamellar vesicles, respectively. Control and optimization of self-assembled aggregates under such experimental conditions should allow the realization and applications of novel nanostructures.