On the mechanism of catastrophic phase inversion in emulsions

This paper reports on the mechanism of catastrophic phase inversion. Experiments were carried out in a stirred vessel where phase inversion was detected by a jump in emulsion conductivity. The system studied contained paraffin oil, water and Triton X-100. The position of the phase inversion has been compared between two emulsification routes of phase inversion, namely the direct emulsification route and the wash-out route. The locus of phase inversion was found to be strongly different for both cases. In particular for the wash-out route the way of dilution appeared to be an important parameter, which to our knowledge has never been studied in detail before. Our experiments show that the locus of catastrophic phase inversion is determined by the added volume of the dispersed phase at each step of the dilution rather than the addition rate. This observation is explained on the basis of the role of multiple emulsion formation in catastrophic phase inversion.