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Phase behavior of CO2-expanded fluorinated microemulsions.

Authors :
Kho YW
Conrad DC
Knutson BL
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