Abstract
A new phase inversion method was developed by modifying the membrane emulsification method with preliminary emulsification. A phase-inverted O/W emulsion of which the volume fraction of dispersed phase, φ, was higher than 0.5 was prepared by passing a pre-emulsified low concentration W/O emulsion (φ<0.5) through a hydrophilic polytetrafluoroethylene (PTFE) membrane. A hydrophobic PTFE membrane was used to prepare the phase-inverted W/O emulsion from the pre-emulsified O/W emulsion. The highest dispersed phase volume fraction, φmax, of the phase-inverted emulsions obtained in this study was 0.90 and 0.84 for the O/W and for the W/O type emulsions respectively. The phase-inverted high concentration emulsions showed high stability. The values of φmax as well as the stability of the phase-inverted emulsions depended on the kind and concentration of emulsifying agents used.
