Water structuring at colloidal surfaces

Abstract

Colloids in contact with water exert control over the arrangement of the first shell of the surrounding water by means of polar, dispersion and directed hydrogen-bonding effects. The preferred orientations of this first shell water are affected by the favored orientations of the second and more distant aqueous shells. If the colloid surface is flexible, it enables greater freedom of movement within the surface water molecules whereas if the surface is fixed, the adjacent water is more static and more extensively structured. The surface structuring of water is affected by, and will affect, the thermodynamics and kinetics for the binding of other molecules to the surface. In this paper, examples of the organization of water at colloidal surfaces are described and general conclusions drawn. These examples include (C-60-I-h){[}5,6] fullerene, beta-helix antifreeze proteins, and oxomolybdate clusters.