COLL 3 |
| R. Nagarajan, Department of Chemical Engineering, Department of Chemical Engineering, The Pennsylvania State University, Fenske Laboratory, University Park, PA 16802 |
| Supercritical carbon dioxide (SCF-CO2) has been proposed as an environmentally friendly solvent, to replace organic solvents, in many industrial applications. The realization of this idea is limited by the solvent power of SCF-CO2, which is poor for most most hydrophilic and hydrophobic substances. To enhance its solvent power, the use of block copolymers as surfactants is actively being considered. In this paper, we consider systems containing block copolymers and SCF-CO2. We examine theoretically, the conditions under which aggregate formation occurs, the shape of the aggregates, their micro-structural features and the ability of the aggregates to solubilize CO2-phobic substances. The properties of the solvent are represented through the simple solubility parameter concept of Hildebrand and Scatchard. The magnitude of the solubility parameter and its dependence on temperature and pressure are estimated using thermodynamic data available in the form of generalized compressibility and enthalpy departure function charts. From the predictive calculations, we delineate pressure domains where the block copolymer molecules simply precipitate and not form solutions, where micelle formation occurs, and where the aggregates disappear and the block copolymer molecule simply exists in the dissolved state. There is considerable incorporation of the solvent (SCF-CO2) in the aggregate core. |
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ACS Award in Colloid and Surface Chemistry Symposium Honoring Clay Radke
Division of Colloid and Surface Chemistry |