Formation of Two-Phase Multiple Emulsions by Inclusion of Continuous Phase into Dispersed Phase
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- 作者：Jong-Moon Lee ; Kyung-Hee Lim ; and Duane H. Smith
- 刊名：Langmuir
- 出版年：2002
- 出版时间：October 1, 2002
- 年：2002
- 卷：18
- 期：20
- 页码：7334 - 7340
- 全文大小：162K
- 年卷期：v.18,no.20(October 1, 2002)
- ISSN：1520-5827
文摘
The formation of multiple emulsions, M/O/M, has been observed for conjugate middle-phase microemulsion(M) and top or oleic (O) phase formed by the system 2-butoxyethanol/n-decane/water at a temperature (35.0
C) about midway between the critical endpoint temperatures (i.e., lowest and highest temperatures atwhich top, middle, and bottom phases can coexist) of this system. The M/O/M morphology was discoveredby measuring the electrical conductivities of steady-state emulsions and confirmed by photomicrography;it was formed by the top and middle phases of the top-middle-bottom tie triangle, as well as by conjugatephases of other tie lines between the top-middle limiting tie line and the microemulsion-oleic phasecritical point. The volume fractions of microemulsion in the cores of the multiple emulsions were calculatedfrom the conductivity measurements. They decreased with increasing volume fraction of oleic phase in thesystem. Inversion of O/M emulsions to the M/O emulsion occurred at still smaller volume fractions ofmicroemulsion in the system, after the volume fraction of microemulsion in the cores apparently haddecreased to zero. It is suggested that the line of phase compositions at which the core volume apparentlygoes to zero may terminate at the microemulsion-oleic phase critical point, where the hysteresis lines forO/M 
M/O, and M/O O/M inversions also terminate. No evidence was found for decreases of volumefraction of continuous oleic phase with decreasing volume fraction of oleic phase in the system or for thehypothetical morphology change M/O/M M/O, caused by "disappearance" of continuous M phase. Thisappears to be the first observation of the formation of multiple emulsions by microemulsion and oleicphases at a temperature between the two critical-endpoint temperatures. Also, we have observed that theemulsion inversion path was quite different from that in previous studies. In these studies inversion tookplace through the morphology change of O/W to W/O/W to W/O. However, in our study the inversion tookplace through the change of M/O/M to O/M to M/O. That is, multiple emulsions M/O/M were formed firstby inclusion of M phase into O-phase drops. Then the M/O/M emulsions inverted to O/M emulsions at whichthe volume fraction of M-phase droplets in the core became zero. From this point on O/M morphology wasmaintained with increasing O-phase fraction up to the emulsion inversion point, and then inversion toM/O took place.
C) about midway between the critical endpoint temperatures (i.e., lowest and highest temperatures atwhich top, middle, and bottom phases can coexist) of this system. The M/O/M morphology was discoveredby measuring the electrical conductivities of steady-state emulsions and confirmed by photomicrography;it was formed by the top and middle phases of the top-middle-bottom tie triangle, as well as by conjugatephases of other tie lines between the top-middle limiting tie line and the microemulsion-oleic phasecritical point. The volume fractions of microemulsion in the cores of the multiple emulsions were calculatedfrom the conductivity measurements. They decreased with increasing volume fraction of oleic phase in thesystem. Inversion of O/M emulsions to the M/O emulsion occurred at still smaller volume fractions ofmicroemulsion in the system, after the volume fraction of microemulsion in the cores apparently haddecreased to zero. It is suggested that the line of phase compositions at which the core volume apparentlygoes to zero may terminate at the microemulsion-oleic phase critical point, where the hysteresis lines forO/M M/O, and M/O O/M inversions also terminate. No evidence was found for decreases of volumefraction of continuous oleic phase with decreasing volume fraction of oleic phase in the system or for thehypothetical morphology change M/O/M M/O, caused by "disappearance" of continuous M phase. Thisappears to be the first observation of the formation of multiple emulsions by microemulsion and oleicphases at a temperature between the two critical-endpoint temperatures. Also, we have observed that theemulsion inversion path was quite different from that in previous studies. In these studies inversion tookplace through the morphology change of O/W to W/O/W to W/O. However, in our study the inversion tookplace through the change of M/O/M to O/M to M/O. That is, multiple emulsions M/O/M were formed firstby inclusion of M phase into O-phase drops. Then the M/O/M emulsions inverted to O/M emulsions at whichthe volume fraction of M-phase droplets in the core became zero. From this point on O/M morphology wasmaintained with increasing O-phase fraction up to the emulsion inversion point, and then inversion toM/O took place.