COLL 212 |
| Bin Xu, Jason S. Keiper, Tracey Bucholz, Joseph M. Desimone, and Charles S. Johnson Jr. Chemistry Department, University of North Carolina-Chapel Hill, Venable Hall, Chapel Hill, NC 27599-3290 |
| Liquid carbon dioxide is a poor solvent for polar compounds such as water, though it is an environmentally benign solvent. Recently it is found that water can be efficiently dispersed in CO2 by means of a few microemulsion forming surfactants including perfluoropolyether carboxylate ammonium salt (PFPE-NH4) and some phosphate fluorosurfactants. Here we report NMR studies of the synthesized phosphate fluorosurfactant series of bis [2(F-hexyl) ethyl] phosphate (DiF8) with different counter ions, like Na+, NH4+ and N (CH3)4+. These surfactants can form micelles or water/CO2 (W/C) microemulsions with high mole ratio of water to surfactant (WO) when conditions are appropriate. A high pressure recirculating system was used in this work. The incorporated PEEK NMR sample cell (1.4 mm ID) was precisely bored in-house with a gun drill, to provide much larger signal intensities relative to the previously used fused silica capillary tubes. NMR relaxation and diffusion measurements were made on components in the microemulsions in the pressure range 2000 – 4500 psi at 25°C. The effect of counter ions, the mobility and structure of microemulsion droplets and the movement of water and other components will be discussed. |
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Posters: Fundamental Research in Surface and Colloid Chemistry
6:00 PM-8:00 PM, Monday, March 29, 2004 Disneyland -- North Exhibit Hall, Poster
Division of Colloid and Surface Chemistry |