title: Superhydrophobic surfaces from hierarchically structured wrinkled polymers.
abstract: This work reports the creation of superhydrophobic wrinkled surfaces with hierarchical structures at both the nanoscale and microscale. A nanoscale structure with 500 nm line gratings was first fabricated on poly(hydroxyethyl methacrylate) films by nanoimprint lithography while a secondary micro-scale structure was created by spontaneous wrinkling. Compared with random wrinkles whose patterns show no specific orientation, the hierarchical wrinkles exhibit interesting orientation due to confinement effects of pre-imprinted line patterns. The hierarchically wrinkled surfaces have significantly higher water contact angles than random wrinkled surfaces, exhibiting superhydrophobicity with water contact angles higher than 160° and water sliding angle lower than 5°. The hierarchically structured wrinkled surfaces exhibit tunable wettability from hydrophobic to superhydrophobic and there is an observed transition from anisotropic to isotropic wetting behavior achievable by adjusting the initial film thickness.
authors.affiliation: Department of Polymer Science and Engineering, University of Massachusetts , 120 Governors Drive, Amherst, Massachusetts 01003-9263, United States.
authors.forename: Yinyong
authors.initials: Y
authors.lastname: Li
authors.forename: Shuxi
authors.initials: S
authors.lastname: Dai
authors.forename: Jacob
authors.initials: J
authors.lastname: John
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Carter
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*; D017155:Wettability
chemical_list: D011108:Polymers; D014867:Water