ON THE PROBLEM OF ACID-BASE INTERACTION DETERMINATION FOR WEAKLY POLAR SOLIDS - CHOLESTEROL SURFACES

The problem of experimental determination of the true acid-base, electron acceptor, γ+S, and electron donor, γ-s, components of the surface free energy of a weakly polar solid is made apparent for cholesterol by the different values of these components, obtained from contact-angle measurements of cholesterol pellets and of a thin layer of cholesterol deposited on a glass slide from solution in chloroform after chloroform evaporation, and also from thin-layer wicking. In these experiments, the following liquids were used: n-octane, n-deeane, diiodomethane, bromoform, α-bromonaphthalene, formamide, ethylene glycol, and water. Although the most probable values of the surface free energy components, γLWS = 48.8, γ+S = 4.2, and γ-S = 0 mJ/m2, are given, the problem of their determination is still open. © 1993 Academic Press, Inc.