Debonding energy of PDMS: A new analysis of a classic adhesion scenario.

We investigated the debonding energy between confined layers of a soft elastic solid (PDMS) and a circular steel indenter in a flat punch geometry. PDMS is extensively used in applications, but also a widespread model system for fundamental research. Varying systematically the pulling speed and the viscoelastic properties, notably the modulus, we determined scaling laws for the debonding energy. We showed that the debonding energy is independent of the sample thickness. Applying a new approach and separating the crack initiation and the propagation part of the force curves, we analyzed the thickness dependence more precisely and we demonstrated that the energy to propagate the crack at given average speed does not only depend on the modulus, but also on the sample thickness.