Correlations of Surface Free Energy and Solubility Parameter with Dielectric Constant and Density for Inorganic...

There should be some intrinsic correlations between the surface free energy (γ) and solubility (δ) parameters, called characteristic parameters here, of substances with their basic physical properties such as the relative dielectric constant (ε_r) and density (ρ), because they are all related to intermolecular interactions. Several correlations have been proposed empirically (or semiempirically) for liquids, but not for solids. It is essential to establish such correlations for solids because the estimation of γ and δ for solids is difficult and/or time-consuming. In the current work, the γ, δ, ε_r, and ρ data of 34 inorganic solids were chosen, and possible relationships between the characteristic parameters (γ and δ) and the physical quantities (ε_r and ρ) were explored by a trial-and-error fitting method based on the data of the solids. Six equations relating γ and δ to ε_r and δ were established. The γ parameters include total (γ_t), dispersive (γ_d), and polar (γ_p) ones, and the δ parameters include the Hildebrand parameter (δ_t) and the Hansen-dispersive (δ_d), polar (δ_p), and hydrogen-bonding (δ_h) ones. The empirical equations can be used to estimate the characteristic parameters of inorganic solids from their easily measurable physical quantities.