Hildebrand solubility parameter definition

Often referred to as the solvent cohesive energy density, the Hildebrand solubility parameter is considered to be a measure of the solvent contribution to the cavity term, and is used as a correction factor in the - solvatochromic equation. It is related to the general definition of London cohesive energy between two interacting species ... 

The empirical nature of is obvious, and it would be helpful to replace y by parameters having a sound basis in thermodynamic or statistical mechanical considerations. Recent efforts by Fowkes [40] to relate y to the dispersion forces between molecules at the interface have been especially promising in leading to tractable equations. An interesting direct correlation has been recently pointed out to us by Gar don [49] between the value of y of a solid polymer and the Hildebrand solubility parameter, 6, which is defined as the square root of the molar energy density—i.e., 6 = n/1E/p A simple consideration of the Young equation and the definition of y indicates that when cos 0=1,... 

This is the so-called one-component solubility parameter or also Hildebrand solubility parameter [29,30]. Other definitions of solubility parameters extend this concept and include the various contributions to intermolecular interactions in multicomponent polar and nonpolar liquids. Expressed in the experimentally... 

According to Hildebrand s solubility parameter approach [101], two liquids are miscible if their solubility parameters 8 differ by no more than 3.4 units [101, 102] cf. Eqs. (2-1) and (5-77) for the definition of 8. That is, mutual miscibility decreases as the 8 values of two solvents become farther apart. Higher mutual solubility will follow if the 8 values of the solvents are closer. A comprehensive collection of 8 values has been given by Barton [100]. 

Definition of 6—Hildebrand proposed the name solubility parameter for the following quantity ... 

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