The adhesion of dry particles in the nanometer to micrometer-size range

The physics of particle adhesion is a complex subject and depends on the interaction mechanisms and the mechanical properties of the contacting materials. These interactions, which tend to be caused by van der Waals and electrostatic interactions, generate stresses that, in turn, result in deformations of the contacting materials. Most of today’s understanding of particle adhesion is based on theories that assume that the adhesion-induced strains are small. Examples of such theories include those proposed by Derjaguin et al. for small particles and high modulus materials and Johnson et al. (K.L. Johnson, K. Kendall, A.D. Roberts, Proc. R. Soc. London A324 (1971) 301) for more compliant materials and larger particles. However, for small particles, the strains can be quite large, resulting in yielding and plastic deformations. In some instances, the entire particle can become engulfed by the substrate. This paper discusses the nature of the deformations, as are presently known, and extrapolates today’s understanding of particle adhesion, which is based on the micrometer-size scale, to the regime of nanometer-size particles.