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

Abstract

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.

Correlations of Surface Free Energy and Solubility Parameters with Dielectric Constant, Refractive Index, and Density for Liquids

“…1−3 Therefore, there must exist some intrinsic correlations between the characteristic parameters (γ and δ) and the fundamental physical quantities (ε r , n D , and ρ) for substances. 1,2,31 empirical (or semiempirical) equations relating γ t , δ t , and δ d to ε r and n D have been proposed for liquids so far, 32−42 but their accuracy and applicability are limited (see Results and Discussion). We noticed that almost all of the equations previously proposed do not involve density, an important physical quantity of substances.…”

“…Some fundamental physical properties of substances such as the relative dielectric constant (ε r ), refractive index ( n D ), and density (ρ) are closely related to the intermolecular interactions, similar to the cases of γ and δ parameters. − Therefore, there must exist some intrinsic correlations between the characteristic parameters (γ and δ) and the fundamental physical quantities (ε r , n D , and ρ) for substances. ,, Several empirical (or semiempirical) equations relating γ t , δ t , and δ d to ε r and n D have been proposed for liquids so far, − but their accuracy and applicability are limited (see Results and Discussion). We noticed that almost all of the equations previously proposed do not involve density, an important physical quantity of substances.…”