Viscosity and hydrophobicity of interfacial water

GEOC 83

Steve Granick, Departments of Materials Science and Engineering, of Chemistry, and of Physics, Departments of Materials Science and Engineering, of Chemistry, and of Physics, University of Illinois, 104 S Goodwin, Urbana, IL 61801
Properties of water at interfaces are of widespread environmental, technological, and biological interest but the details are disputed. Using a surface forces apparatus, we have measured the frequency- and rate-dependent responses to impulses applied in the shear direction and also in the direction normal to this. From studies using an assortment of counterions(monovalent, divalent, trivalent), film thickness (from nanometers to micrometers), and wettability (from hydrophilic to controlled extents of hydrophobicity), a provocative picture emerges of a dynamical structure whose complex responses are qualitatively unlike those possessed by simpler Lennard-Jones fluids.