Determination of Intermolecular Forces by Surface-Chemical Techniques

The intermolecular forces operative between adjacent phases include the ever-present dispersion forces; various dipole and ionic interactions; hydrogen-bonding and electron-transfer complexes; and the metallic bond. For any given interface the nature of the forces that can operate between the two materials may reduce to dispersion forces alone or dispersion forces plus hydrogen-bonding. Means to evaluate the magnitudes of these interacting foices, based on measurements of contact angles, interfacial tensions, and heats or free energies of immersion or adsorption, are set forth. Examples are shown in which the wettability of solids by liquids is best predicted by considering the actual type of intermolecular forces involved at the interface.