Double Phase Inversion of Emulsions Stabilized by Layered Double Hydroxide Particles and Sodium Dodecyl Benzene Sulfonate

Abstract

The occurrence of double phase inversion of emulsions stabilized by positively charged layered double hydroxide (LDH) particles and single-chain anionic surfactant sodium dodecyl benzene sulfonate (SDBS) has been investigated. That is, the original oil-in-water (ow(1)) emulsions inverted to water-in-oil (w/o) type and finally reconverted to o/w(2) emulsions. Laser-induced fluorescent confocal micrographs and emulsion droplet size measurements together confirmed that the initial o/w(1) and intermediate w/o emulsions are stabilized by LDH particles, whereas the final o/w(2) emulsions are stabilized mainly by excess SDBS surfactants. The adsorption behavior of SDBS on LDH particles was further studied by combining x-ray diffraction, zeta potential measurements, and contact angle measurements to reveal the inversion mechanism.