17 Adhesion and Wetting Phenomena
17.1 Surface and Interfacial Energies
In Part I we saw how various interaction potentials between molecules arise, and we considered the implications of the energy minimum, or the “adhesion” energy, of molecules in contact. Here we shall look at phenomena involving particles and extended surfaces in adhesive contact, and it is best to begin by defining some commonly used terms and deriving some useful thermodynamic relations.
Work of adhesion and cohesion in a vacuum. These are the free energy changes, or reversible work done, to separate unit areas of two surfaces or media from contact to infinity in a vacuum (Figure 17.1a, b). For two different media (1 ≠ 2), this energy is referred to as the work of adhesion ...