Design of Ordered Wrinkled Patterns with Dynamically Tuned Properties

Abstract

The formation of patterned surfaces is a common tool to engineer materials. The capability to design and reproduce detailed features is a key factor to fulfill requirements for functional surfaces. Generation of wrinkles via buckling of a stiff film on a compliant surface is an inexpensive, easy and reliable method to yield a patterned surface. The wrinkling method has been exploited in a wide variety of areas, including photovoltaics, microfluidics, adhesion, and anti-fouling systems. Here we show the ability to obtain deterministically ordered herringbone patterns. In a biaxially pre-stretched PDMS sample a thin film of a stiff coating is deposited by initiated chemical vapor deposition (iCVD). iCVD is a solvent- free technique that yields a conformal thin coating on virtually any substrate, giving a controllable thickness and tunable structural, mechanical, thermal, wetting, and swelling properties. Sequential release of the film-substrate system shows the transition from 1-D ripples to an ordered herringbone pattern. Wrinkle features can be controlled adjusting the film thickness, the initial load and the release process. Moreover, the surface topography can be dynamically tuned by applying a controlled mechanical stimulus. These properties make these materials excellent candidates for flexible applications.