Contact instability in adhesion and debonding of thin elastic films

Abstract

Based on experiments and 3D simulations, we show that a soft elastic film during adhesion and debonding from a rigid flat surface undergoes morphological transitions to pillars, labyrinths, and cavities, all of which have the same lateral pattern length scale, λ close to λ/H˜3 for thick films, H>1 #956;m. The linear stability analysis and experiments show a new thin film regime where λ/H≈3+2π(λ/3 μH)^1/4 (γ is surface tension, μ is shear modulus) because of a significant surface energy penalty (for example, λ/H≈6 for H=200 nm; μ=1 MPa).