we demonstrated the wrinkling behavior of nanopatterned PS films, whose wrinkle wavelength and resultant morphology depend strongly on geometric parameters of surface patterns as well as the direction of the applied strain relative to the nanopattern orientation. The effect of the nanopattern on the wrinkle wavelength was more significant when the pattern was oriented parallel to the compression direction, resulting in an increase in the wavelength anisotropy for the higher h2/h1 ratios. The anisotropic wrinkling behavior of these films was interpreted quantitatively in terms of the effective thickness based on a composite model. We believe this study offers a simple route to designing anisotropic hierarchical structures for potential applications including tunable wetting and adhesion, optics and microfluidics. Our approach also provides insight into the effect of surface roughness in predicting the wrinkling wavelength, which has direct implications in use of surface wrinkling to measure the mechanical properties of rough films.
Citation: Nano Letters
Pub Type: Journals
wrinkling, nanoscale, patterns, roughness, mechanics