Multiple emulsions osmotic flow

One of the main instabihties of multiple emulsions is the osmotic flow of water from the internal to the external phase, or vice versa, which leads to shrinkage or sweUing of the internal water droplets, respectively. This process assumes the oil layer to act as a semi-permeable membrane (permeable to water, but not to solute). 

Optimum osmotic balance of the internal and external aqueous phases. If the osmotic pressure of the internal aqueous droplets is higher than the external aqueous phase, water will flow to the internal droplets and result in swelling of the multiple emulsion drops with the ultimate production of a W/O emulsion. In contrasL if the osmotic pressure in the outside external phase is higher, water will diffuse in the opposite direction and the multiple emulsion will revert to an O/W emulsion. 

The oil layer separating the inner and outer aqueous phases behaves as a semipermeable membrane The release of solutes from a W/OAV multiple emulsion, for instance, only occurs through breakdown of the multiple droplets as a result of osmotic flow of water to the inner phase and consequent coalescence of the droplets. 

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