Interaction at interfaces and induction of surface free energy components

Abstract

A set of published data on surface free energy (γ1, γ2) and interfacial energy (γ12) for interfaces mercury-organic liquid, mercury-water, and water-organic liquid (125 pairs altogether) has been critically evaluated. It has been found that the Antonow rule does not hold, that the Neumann equation is suitable for determining the work of adhesion, if γ1 and γ2 are not too different, and that the Fowkes equation can be used to assess the type of interaction at the interface. A hypothesis has been suggested which states that, besides the interaction between dispersion components of the surface free energies of the adjoining phases and the interaction between the non-dispersion components of the same type in bulk, a non-dispersion component of one phase may interact by inducing a component of the same type in the other phase near the interface. Relations concerning the mechanism of interaction at the interface have been derived. Also, the relation between the Girifalco-Good, Neumann and complemented Fowkes equation has been evaluated. For the particular liquids the dispersion portion of their surface free energies and the interaction mechanism at their interface with water and mercury have been estimated. For water, e.g. the polar component of the surface free energy (14.7 mJ m-2) and the hydrogen-bond component (36.3 mJ m-2) have been determined. The introduction of the induced component of the surface free energy is shown, as an example, for water-aromatic hydrocarbons and water-alcohols systems.