The curious world of hydroxide surfactants. Spontaneous vesicles and anomalous micelles

Abstract

Double-chained cationic surfactants typified by dodecyldimethylammonium bromide are insoluble in water, forming lamellar liquid crystal phases. They form vesicles only on prolonged sonication. If the halide ion is replaced by a hydroxide, the resulting surfactants are highly soluble and form spontaneously a clear solution which appears to comprise a mixture of small micelles and fairly monodisperse vesicles. The distribution of particle size changes with added base or with partial titration with acid (HBr, HCl, HF) which can sometimes yield vesicles with an initially unsymmetric distribution of anions. Evidence for these structures from quasi-elastic light scattering (QELS) and viscosity measurements and an account of their extraordinary properties are presented. Show more