Formation, evolution and transition of multiple surface patterns in metal films on polymer substrates under uniaxial loading

Strain-induced surface structures are very common in natural systems and they are very useful for a wide range of applications. In this work, we report on the formation, evolution and transition of multiple surface patterns in zinc/polydimethylsiloxane systems with varied film thicknesses under cyclic uniaxial loading. It is found that the mechanical compression leads to buckling patterns while the mechanical tension induces channel cracks. The buckling patterns include two classes of distinct morphologies: homogeneous wrinkling and localized buckle-delamination, depending on the film thickness. The morphological characteristics and in situ evolutional behaviors of the wrinkling, buckle-delamination and cracking are described and discussed in detail. The phenomenon of wrinkle-to-delamination transition is analyzed by a two-dimensional phase diagram and is used to measure the interfacial adhesion strength between the film and substrate. The report in this work can promote better understanding of the phenomenon of wrinkle-to-delamination transition and the complex interactions between the multiple surface patterns under mechanical loading.