Direct observations of deformations resulting from particle-substrate adhesion

Abstract

Deformations of planar substrates and contacting particles due to surface forces, such as the van der Waals interactions, were postulated long ago. Direct observations of such deformations between submicrometer Kynar 301 F™ particles and substrates consisting of polyester-siloxane block copolymers or polished silicon, obtained using scanning electron microscopy (SEM), are presented. The deformations observed in the polyester-siloxane substrate are too large to be explained using Hertzian theory of elastic behavior but are consistent with the plastic deformation model of Krupp and the tensile model of Johnson et al. Potential experimental artifacts, such as space charge effects and the effect of using conducting coatings, are discussed.