Advances in Colloid and Interface Science (v.99, #1)

The terminology and the physical sense of percolation and permeability were analyzed. Existing theories of percolation and permeability were analytically compared with respect to their applicability and effectiveness. It is concluded that the main tendency in the development of the concept of percolation/permeability consists in the fundamental investigation of the relationship between the preparation conditions of the solid, its structural characteristics and measured properties — not only percolation/permeability but also adsorption, Hg-intrusion, etc.
Keywords: Theories of percolation; Theories of permeability; Solid–fluid systems; Solid structures;

This review links together for the first time both the practicalities of force measurement and the work carried out to date on force detection between polymeric surfaces in liquids using the atomic force microscope (AFM). Also included is some of the recent work that has been carried out between surfactant surfaces and biologically coated surfaces with the AFM. The emphasis in this review is on the practical issues involved with force measurement between these types of surfaces, and the similarities and irregularities between the observed types of forces measured. Comparison is made between AFM and surface force apparatus (SFA) measurements, as there is a much longer history of work with the latter. Results indicate that forces between the surfaces reviewed here are a complicated mixture of steric-type repulsion, conformational behaviour on separation and long-range attraction, which is often ascribed to ‘hydrophobic’ forces. The origin of this latter force remains uncertain, despite its almost ubiquitous appearance in force measurements with these types of surfaces.
Keywords: Atomic force microscope (AFM); Force curves; Polymer surfaces; Forces in liquids; Spring constant measurement;