Irv Wiehe developed the two-dimensional solubility parameter approach for solvent selection. Each liquid is characterized by a complexing solubility parameter component and a field force solubility parameter component. As shown in the example solubility parameter map below, the points represent different liquids that remain fixed. The solvents for a solute (a polyester copolymer here) form a polygon area on this diagram. Then one knows that the liquids that are enclosed by the polygon are also solvents for the solute. By using a volume fraction lever rule, one can predict which mixtures of liquids will dissolve the solute. By mixing a nonsolvent on one side of the polygon with a nonsolvent on the opposite side of the polygon, one can actually form a solvent by mixing nonsolvents (open circles on the diagram below). For solutes believed to have only a few solvents, the two-dimensional solubility technique can determine almost an infinite number of possibilities by mixing two or more liquids in various proportions. No limit on the solute has been found, as long as it can be dissolved in at least one liquid. It has been applied to polymers, organic compounds, petroleum derived oils, and coal liquids.
Solubility Parameter Map for Polyester Copolymer at 4 g/L
More detailed information can be found by contacting Irv Wiehe or reading :
1. I. A. Wiehe, "Polygon Mapping with Two-Dimensional Solubility Parameters", I&EC Research, 34, 661-673 (1995).
2. I. A. Wiehe, "Two-Dimensional Solubility Parameter Mapping of Heavy Oils", Fuel Sci. & Tech. Int'l, 141, 289-312 (1996).
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