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Phase behavior of CO2-expanded fluorinated microemulsions.
- Source :
-
Langmuir : the ACS journal of surfaces and colloids [Langmuir] 2004 Mar 30; Vol. 20 (7), pp. 2590-7. - Publication Year :
- 2004
-
Abstract
- The formation of CO2-expanded, fluorinated reverse microemulsions is demonstrated for the system of perfluoropolyether (PFPE) surfactant (ClPFPE-NH4, MW = 632) and PFPE oil (PFPE, MW = 580). The phase behavior of this system is examined as a function of temperature (25-45 degrees C), pressure, CO2 concentration, and water to surfactant molar ratios (W0 = 10 and 20). Visual observations of one-phase behavior consistent with reverse microemulsion formation are further supported by spectroscopic measurements that establish the existence of a bulk water environment within the aqueous core. Microemulsion formation is not observed in the absence of CO2 for this PFPE surfactant/PFPE oil system, and a CO2 content greater than 70 mol % is required to induce microemulsion formation. Over the range of water loadings and temperatures investigated, the lowest cloud point pressure is observed at 46 bar (5 wt % ClPFPE-NH4 in PFPE oil, W0 = 20, xCO2 = 0.7, T = 25 degrees C). In the regions where one-phase behavior is observed, the cloud point pressures increase with temperature, water loadings, and CO2 content. The driving forces of microemulsion formation in the CO2-expanded fluorinated solvent are discussed relative to traditional reverse microemulsions and CO2-continuous microemulsions.
Details
- Language :
- English
- ISSN :
- 0743-7463
- Volume :
- 20
- Issue :
- 7
- Database :
- MEDLINE
- Journal :
- Langmuir : the ACS journal of surfaces and colloids
- Publication Type :
- Academic Journal
- Accession number :
- 15835128
- Full Text :
- https://doi.org/10.1021/la035529z