Characterization of solid-stabilized water/oil emulsions by scanning electron microscopy

The structure of water-in-paraffin oil emulsions stabilized by both cationic surfactant (CTAB) and silicon oxide nanoparticles is investigated. A transition in the geometry of the droplets, which from spherical turns polymorphous, is discussed on the basis of scanning electron microscopy observations. The freeze-fracture technique is employed in addition to a sublimation procedure helping the visualization of the inner structure of the droplets. Their deformation is shown to be a consequence of the interplay between nanoparticles, CTAB and interfacial properties. For polymorphous droplets the existence of a network of self assembled particles bridging them from part to part is evidenced.