Molecular explanation for why talc surfaces can be both hydrophilic and hydrophobic.

ABSTRACT: While individual water molecules adsorb strongly on a talc surface (hydrophilic behavior), a droplet of water beads up on the same surface (hydrophobic behavior). To rationalize this dichotomy, we investigated the influence of the microscopic structure of the surface and the strength of adhesive (surface-water) interactions on surface hydrophobicity. We have shown that at low relative humidity, the competition between adhesion and the favorable entropy of being in the vapor phase determines the surface coverage. However, at saturation, it is the competition between adhesion and cohesion (water-water interactions) that determines the surface hydrophobicity. The adhesive interactions in talc are strong enough to overcome the unfavorable entropy, and water adsorbs strongly on talc surfaces. H

SUBMITTER: Rotenberg B 

PROVIDER: S-EPMC3249429 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature