Complex buckling instability patterns of nanomembranes with encapsulated gold nanoparticle arrays

The nanomechanical properties of micropatterned nanomembranes containing gold nanoparticle microarrays were investigated with the buckling instability method. An unusual, complex pattern of buckling instability was observed for the nanoscale polymeric films under compressive stresses. An intriguing two-stage wrinkling was observed for these nanoscale films with spatially correlated instabilities. Two concurrent strain-dependent buckling modes were observed above a certain critical strain. Transformation from conventional transversal buckling mode to zigzag buckling is attributed to the development of the biaxial stress along the boundary lines for micropatterned areas. The binary buckling pattern observed here allowed the "one-shot" evaluation of the elastic moduli of two compositionally different regions (with and without gold nanoparticles).