Influence of Elastic Modulus of a Soft Elastomer on Adhesion to Rough Surfaces

In the field of adhesion science, it is of practical importance to understand how roughness affects adhesion. This is of direct relevance in designing adhesives for applications in the areas of microelectronics, biomedical devices, and composites. The main idea is to have the adhesives conform to the roughness and approach close enough for van der Waals (or other electrostatic) interactions to be effective. The first complete mathematical formulation for roughness was put forward by Greenwood and Williamson using a single-length-scale model describing the surfaces as hemispherical asperities with a Gaussian distribution of heights. Bo Persson has proposed a multi-scale model to calculate the adhesion energy as a function of modulus and roughness, as described using the power spectral density of topography. Here we have performed contact and fracture mechanics experiments for smooth cross-linked polydimethylsiloxane with varying elastic modulus on polycrystalline diamond surfaces with varying roughness, which have been characterized to obtain accurate multi-scale power spectral densities. We will present the comparison between the predicted adhesion energies calculated using Persson’s theory and the experimental adhesion energy measured during approach and separation.