Controllable Buckle Delaminations in Polymer-Supported Periodic Gradient Films by Mechanical Compression

Surface instabilities including wrinkles and buckle-delaminations are widespread in nature and can be found in a wide range of practical applications. Compared with the homogeneous wrinkle mode, the buckle-delaminations are spontaneously stress-localized, and their initiation positions and geometrical parameters are hardly precisely controlled by a simple method. Here, we report on the controllable buckle-delaminations in periodic thickness-gradient metal films on polydimethylsiloxane (PDMS) substrates by uniaxial mechanical compression. It is found that a periodic thickness-gradient film is spontaneously formed by masking a copper grid during deposition. The released mechanical strain tends to concentrate in thinner film regions, resulting in the restricted growth of buckle-delaminations. The geometrical features, evolutional behaviors, and underlying physical mechanisms of such buckle-delaminations are analyzed and discussed in detail based on the buckling model and finite element simulations. This work would provide a better understanding of the restricted buckle-delaminations in heterogeneous film-substrate systems and controllable fabrication of ordered structural arrays by copper grid masking and mechanical loading.

Automated summary

This study investigates the controllable buckle-delaminations in periodic thickness-gradient metal films on polydimethylsiloxane (PDMS) substrates through uniaxial mechanical compression. It is found that the thickness gradient in the film leads to the concentration of mechanical strain in thinner regions, restricting the growth of buckle-delaminations. The geometric features, evolutional behaviors, and physical mechanisms of such buckle-delaminations are analyzed and discussed using buckling model and finite element simulations.