Measurement of Particle and Surface Interactions Using Force Microscopy

This chapter describes the use of the atomic force microscope (AFM) to quantitatively measure surface forces arising from the interactions between particles and between particles and surfaces. These forces are of particular interest in the study of colloidal dispersions, where the strength of interactions between particles governs the properties of the dispersion overall. Most traditional methods used to study colloidal dispersions are ensemble techniques, where the interactions of a large number of particles are measured simultaneously. The advantage with the AFM is the ability to make measurements on the single-particle level and to measure forces, and hence interaction energies, with respect to intersurface distances. Colloid probes, interaction forces, and adhesion forces measured by AFM and effect of roughness on measured adhesion and surface forces are discussed in this chapter. The forces that are likely to be encountered when measuring interactions between particles and between particles and surfaces while using the AFM are described with examples of the measurements. This study will serve a useful and practical guide to one undertaking such measurements.