On-line light backscattering tracking of the transitional phase inversion of emulsions

A surfactant/oil/water system (Brij 30/decane/brine) is stirred while continuously changing the temperature in order to induce the swap of the emulsion morphology from O/W to W/O or vice versa. The transitional phase inversion is detected by monitoring both the electrical conductivity and the light backscattering with a Turbiscan (on line) equipment. The optical technique pinpoints the inversion and exhibits several advantages over the conductivity measurement: (i) it does not require any addition of electrolyte in the aqueous phase, (ii) it provides some information on the drop size, and (iii) it works with both O/W and W/O morphologies whereas conductimetry is blind for the latter case.