title: Controlled Three-Dimensional Hierarchical Structuring by Memory-Based, Sequential Wrinkling.
abstract: This paper describes how a memory-based, sequential wrinkling process can transform flat polystyrene sheets into multiscale, three-dimensional hierarchical textures. Multiple cycles of plasma-mediated skin growth followed by directional strain relief of the substrate resulted in hierarchical architectures with characteristic generational (G) features. Independent control over wrinkle wavelength and wrinkle orientation for each G was achieved by tuning plasma treatment time and strain-relief direction for each cycle. Lotus-type superhydrophobicity was demonstrated on three-dimensional G1-G2-G3 hierarchical wrinkles as well as tunable superhydrophilicity on these same substrates after oxygen plasma. This materials system provides a general approach for nanomanufacturing based on bottom-up sequential wrinkling that will benefit a diverse range of applications and especially those that require large area (>cm(2)), multiscale, three-dimensional patterns.
authors.affiliation: †Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Won-Kyu
authors.initials: WK
authors.lastname: Lee
authors.affiliation: †Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Clifford J
authors.initials: CJ
authors.lastname: Engel
authors.affiliation: †Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Huntington
authors.affiliation: †Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Jingtian
authors.initials: J
authors.lastname: Hu
authors.affiliation: †Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Teri W
authors.initials: TW
authors.lastname: Odom
keywords: Nanowrinkles; hierarchical texturing; polymers; polystyrene; superhydrophilicity; superhydrophobicity