The concentration and type of emulsifier rules the oil/water and water/oil/water emulsion size distribution

In the present work, we studied the effect of increasing different emulsifiers concentration on the size distribution of a simple emulsion (O/W) and double emulsion (W/OW). In one hand, we observed that increasing polycaprolactone (PCL) concentration in the O/W emulsion, the size of the droplets decreased. On the other hand, increasing the concentration of polyvinyl alcohol (PVA), pluronic f68 or bovine serum albumin (BSA) as second emulsion stabilizers of the “W/O/W” emulsion led to micrometer size droplets in all cases up to 7 μm. Also, when the concentration of pluronic f68 increased from 1.5% w/v to 6.0% w/v the size distribution of the double emulsion turned from polydisperse to monodisperse. We conclude that the chemical structure of pluronic provide a more stabilizing effect to the emulsion than PVA or BSA. Finally, we studied the inner morphology of the “W/O/W” by Focused Ion Beam technique combined with Scanning Electron Microscopy (FIB-SEM) and confirmed the development of a double emulsion. These results are promising for cosmetics of pharmaceutical applications because it is important to obtain a monodisperse size distribution of the emulsion and a detailed characterization of inner morphology of the microspheres.