Increased Hierarchical Wrinklons on Stiff Metal Thin Film on a Liquid Meniscus

摘要

Wrinklons-the hierarchical merging of wrinkles-are observed on several surfaces including thin films, curtains, graphene sheets, and skin. Wrinklons are a consequence,of the interplay between bending, stretching, and gravitational energies and generally exhibit 1 to 2 hierarchical transitions (lambda(n+1) = 2 lambda(n)). Here we show that parallel and self-similar wrinklons on ultrathin cobalt/chromium film atop a contracting silicone oil meniscus can produce up to, 5 hierarchical-wrinklon transitions near the fluid-solid boundary. Further, these wrinklons do not follow the standard von-Karman wrinklon scaling near the edge, attributed to the added surface energy (L/lambda proportional to (A/t)(031)). A model developed via scale analysis shows (a) the relationship between wavelength and length of the wrinkles and (b) a linear relation between the amplitude and the length of wrinkles at all observed hierarchic levels (L proportional to A), fitted well with previous literature results. This work provides a mechanism for thin-film metal wrinkling on liquids and shows that surface stretching effects can allow increased hierarchical levels in-wrinklons.