Wettability of some low energy surfaces. I. Air/liquid/solid interface

Abstract

The wettability of a number of low energy solid surfaces, including hoof keratin and human skin, has been examined using two liquids, water and methylene iodide, and employing Wu's empirical approach to obtain γ s d and γ s P , the dispersion and polar components of the solid “surface tension.” The sum of these parameters, ( γ s d + γ s p ) was found to be in good agreement with reported values of γ c , the critical surface tension, based on Zisman plots. Using the latter method, γ c values of solids selected from the above group were determined using aqueous ethanol solutions. The values were lower than those obtained using nonpolar liquids, thus confirming earlier findings. A compilation of our own data and data from the literature reveals that the derived values of γ c show little or no dependence on the type of solid surface, the type of alcohol or its chain length. The results can be explained in terms of adsorption of alcohol at the surface of the solid.