科研之友
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摘要
In this report, we systematically investigate the as-formed wrinkles to act as a novel boundary to direct the surface wrinkling for controllable fabrication of hierarchical wrinkling patterns. Here the wrinkled boundary is the highly aligned wrinkling patterns, formed in the O-2 plasma-exposed region (denoted as D-1) when a uniaxially strained polydimethylsiloxane (PDMS) is subjected to the first selective O-2 plasma treatment (OPT) via a copper grid. Subsequently, a stiff crust with the tunable composition is fabricated on the whole PDMS including the O-2 plasma-unexposed region (denoted as D-2), by means of the second OPT and/or additional film deposition (e.g., polystyrene and Pt). The subsequent solvent swelling or heating induces wrinkles in the D-2 region, which are highly oriented perpendicular to those in the D-1 region. The physics underpinning the experimental phenomenon is elucidated by our theoretical analysis based on Koiter';s elastic stability theory and finite element simulations. Additionally, we demonstrate that the wavelengths of the well-organized orthogonal wrinkles can be independently tailored via the exposure duration and the additionally deposited film thickness.
