Gecko-like adhesion at rubber/metal interfaces

Rubber materials would adhere to metal substrates when compressed together for a certain time. The specific mechanisms of such adhesion are still unclear. In this work, silicone rubbers and metals with various chemical structures were utilized to reveal the gecko-like adhesion mechanism. The Sum Frequency Generation Vibrational Spectroscopy (SFG) and in-situ Diffuse Reflaxions Infrared Fourier Transformations Spectroscopy (DRIFTS) results demonstrated that van der Waals forces are the inevitable interactions at any silicone rubber/metal interface. Hydrogen bond interactions can be observed when the interface is rich in hydroxyl groups, contributing to higher adhesion strength and rate. The interactions could be affected once containing other groups (e.g. large steric hindrance groups or certain inorganic fillers) in the chemical structure. This work could provide inspirations for designing the materials with adjustable adhesion ability or intelligent adhesion system.