Slippery or sticky boundary conditions: control of wrinkling in metal-capped thin polymer films by selective adhesion to substrates

As demonstrated by countless studies, sheets are more easily bent than stretched. Under planar forces, a thin sheet will thus deform out of plane by forming wrinkles. Surface buckling or wrinkling can be generated in various systems such as rigid thin films supported on elastomers, or gels that could be swollen or dried. Here, we describe an original and simple method to control the spatial layout of wrinkles in polymer/metal bilayer systems. To generate surfaces with a tailor-made buckling pattern, we have tuned the boundary conditions at the polymer-substrate interface by using chemically patterned substrates with highly contrasted surface free energies ($\gamma )$, easily produced by microcontact printing of alkanethiols on gold substrates. In addition, to explain our original variant of the experiments, we will also expand the existing mechanisms and models described in the literature to take into account the adhesion at the polymer-substrate interface.