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## Hildebrand solubility parameterThe ## Additional recommended knowledge
## DefinitionThe Hildebrand solubility parameter is the square root of the cohesive energy density:
The cohesive energy density is the amount of energy needed to completely remove unit volume of molecules from their neighbours to infinite separation (an ideal gas), which is equal to the heat of vaporisation divided by molar volume. In order for a material to dissolve, these same interactions need to be overcome as the molecules are separated from each other and surrounded by the solvent. Dr. Joel H. Hildebrand suggested the square root of the cohesive energy density as a numerical value indicating solvency behaviour. This later became known as the “Hildebrand solubility parameter”. Materials with similar solubility parameters will be able to interact with each other, resulting in solvation, miscibility or swelling. ## Uses and LimitationsIt provides useful predictions for non-polar and slightly polar ( dipole moment <2 debyes) systems without hydrogen bonding. It has found particular use in polymer / solvent interactions, where it provides useful predictions of solubility and swelling of polymers by solvents. More complicated, 3 dimensional solubility parameters, such as Hansen Solubility Parameters can be used for polar molecules.
## UnitsConventional units are (calories / cc SI units are (MPa) Conversion from the two is by δ (MPa Given the non-exact nature of the use of δ, it is often sufficient to say MPa ## Examples
Data from From the table, poly(ethylene) has a solubility parameter of 7.9 cal
## BibliographyBarton, AFM (1991). Barton, AFM (1990). ## References |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hildebrand_solubility_parameter". A list of authors is available in Wikipedia. |