Singular dynamics in the failure of soft adhesive contacts

We use optical microscopy and high-speed imaging to characterize the rapid recoil of soft, silicone gels after an extreme deformation and release from a point contact during the failure of a soft adhesive contact. The gel immediately recoils away from the final contact point with a self-similar surface profile that evolves as a power law in time, suggesting that adhesive detachment is a space-time singularity. The singular dynamics we observe are consistent with a relaxation process driven by surface stress and hindered by viscous flow of the gel’s free fluid phase through its porous, elastic network. Our results emphasize the importance of accounting for both the liquid and solid phases of gels in understanding their mechanics, especially in extreme deformation.