ABSTRACT
In this chapter, we shall give a brief account of the theory and experimental evidence of the action of surface forces, i.e., forces needed to account for phenomena occurring near surfaces, very thin layers, corners, borders, contact lines, etc. All forces do originate at the microscopic level, but we shall look at the phenomenological, macroscopic manifestations of those forces. In particular, we shall emphasize the role of the so-called disjoining pressure. Such terminology is a bit misleading because, in a number of cases, action would be just the opposite:
conjoining
pressure (attraction). However, current use or historical reasons lead us to maintain the term
disjoining
pressure, whatever the particular situation might be.
