(26g) Novel Fluid-Particle Interaction Mechanisms in Dispersions

Dispersion science holds the key to cost-effective manufacturing of an unimaginably large number of chemicals and consumer products. The control of industrial processes varying from sedimentation, flocculation, and coagulation to the manufacture of advanced self-assembled materials can be greatly improved by a better understanding of the interaction forces between particles and the confining geometries that affect the quality and stability of colloidal dispersions. This is especially the case in a concentrated colloidal dispersion where particles are more likely to come in close contact with one another and become more ordered in the confines of their restricted environment. In recent years, due to the advent of new instrumentation for measuring interaction forces in fluid-particle systems, novel forces, such as the structural force arising from the energy barrier caused by particle microstructuring, and the attractive depletion force caused by the excluded volume effect, have been characterized. This lecture will highlight the role of structural forces in stabilizing dispersions and especially point out their importance in a variety of technological contexts such as particle sedimentation, foam and emulsion stability, wetting, spreading and adhesion of such systems on solid surfaces. Theoretical results based on Monte Carlo simulations and integral equations of statistical mechanics are compared with the experimental data and good agreement is found.