Scattering studies of microemulsions in low-density alkanes

Abstract

Using small-angle neutron scattering and dynamic light scattering we have studied the structure and dynamics of water-in-oil microemulsion droplets stabilised by the surfactant Aerosol-OT in the low-density alkanes propane and n-butane. The phase stability, interdroplet structure and droplet diffusion coefficient are dependent on the alkane density. At densities of ca. 0.6 × 10³ kg m^–3 surfactant-coated, essentially monodisperse, randomly distributed, weakly interacting, spherical water droplets are present. At lower densities enhanced droplet–droplet attractions promote large, transient clusters of droplets. The intradroplet structure (i.e. droplet size) appears to be independent of alkane chain length and density.