New paradigms for spreading of colloidal fluids on solid surfaces

Abstract

Colloidal fluids are used in a variety of technological contexts. For example, their spreading and adhesion behavior on solid surfaces can yield materials with desirable structural and optical properties. The well-established concepts of spreading and adhesion behavior of simple liquids do not apply to colloidal fluids containing nanometer-sized particles, surfactant micelles, proteins, polymers, vesicles, microemulsions, and solvents. This paper reviews recent progress in the spreading of colloidal/nano-fluids over solid surfaces with emphasis on two applications: the spreading of aqueous trisiloxane surfactant solutions (i.e., superspreaders) on hydrophobic solid surfaces driven by the surface tension gradient, and the spreading of thin colloidal films containing nanoparticles on hydrophilic surfaces driven by the structural disjoining pressure gradient (i.e., film tension gradient). These two mechanistic paradigms of dynamic spreading of colloidal fluids on solids are elucidated with experimental observations and mathematical modeling. © 2008 Springer-Verlag.