Bicontinuous and Closed-Cell Foam Emulsions as Continuum Structures in an Oil in Water Emulsion System

Stable emulsions in the ternary toluene/Triton X-100/water system can be prepared for a surfactant to oil weight ratio of 1:5. Emulsions are formed on this continuum between 0.5 and 14 wt % Triton X-100. For all Triton X-100 wt %, an oil in water emulsion is formed. At high Triton X-100 concentrations, a closed-cell fluid foam is stabilized. In addition, a bicontinuous emulsion can be stabilized for several hours for a Triton X-100 composition of 6 wt %. This phase coexists with an oil in water emulsion. The bicontinuous phase is formed only when the input energy is minimized; for higher input energy no stable bicontinuous emulsion could be prepared. Moreover, the bicontinuous phase is extremely sensitive to external stimuli. Four techniques, pulsed gradient spin−echo NMR, rheology, conductivity, and freeze-fracture transmission electron microscopy, were used to probe the microstructures of the stabilized emulsions.