title: Contact angle hysteresis on textured surfaces with nanowire clusters.
abstract: Nanowire arrays with various agglomeration patterns were synthesized by adjusting the solvent evaporation rates. Nanowires with 200 nm diameter and 2-25 microm in length were fabricated from an anodic aluminum oxide (AAO) porous template. Various drying treatments were applied to develop nanostructured surfaces with topological differences. Due to surface tension forces, copper nanowires after thermal and evaporative drying treatments agglomerated into clusters, while supercritical drying technique provided excellent bundled-free and vertically-standing nanowire arrays. Although all dried surfaces exhibited hydrophobic nature, the contact angle hysteresis, or the difference between advancing and receding angles, was found to be larger on those surfaces with bundled nanowire clusters. To explain the difference, the wetted solid fraction on each surface was calculated using the Cassie-Baxter model to show that the hysteresis was contributed by liquid/solid contact area on the textured surfaces.
authors.affiliation: Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Ying-Chih
authors.initials: YC
authors.lastname: Liao
authors.forename: Cheng-Kun
authors.initials: CK
authors.lastname: Chiang
authors.forename: Yen-Wen
authors.initials: YW
authors.lastname: Lu