WETTING AUTOPHOBICITY

Adsorbed films of monolayer or submonolayer thicknesses are detected near nonspreading droplets of a number of organic liquids. The mechanism of formation of these films is shown to be evaporation followed by adsorption and not surface diffusion. The dependence of the film thickness on the distance from the edge of the droplet and the kinetics of adsorption and desorption are determined. The film thickness, decay length, and time constants for adsorption and desorption increase with increasing molecular weight within a series of organic acids. The present results directly demonstrate the idea of autophobicity which was suggested long ago by Zisman and co-workers, and enable the elucidation of its mechanism. © 1991 Academic Press, Inc.