title: Lotus-like biomimetic hierarchical structures developed by the self-assembly of tubular plant waxes.
abstract: Hierarchical roughness is beneficial for superhydrophobic and self-cleaning surfaces. Biomimetic hierarchical surfaces were fabricated by replication of a micropatterned master surface and self-assembly of two kinds of tubular wax crystals, which naturally occur on the superhydrophobic leaves of Tropaeolum majus (L.) and Leymus arenarius (L.). These tubule forming waxes are multicomponent waxes, composed of a mixture of long chain hydrocarbons. Thermal evaporation of wax was used to cover artificial surfaces with a homogeneous wax layer and tubule formation was initiated by temperature and a solvent vapor phase. Based on this technique, various nanostructures produced by three-dimensional tubular waxes have been fabricated by changing the wax mass. Fabricated structures and surface chemistry mimic the hierarchical surfaces of superhydrophobic and self-cleaning plant surfaces. The influence of structures on superhydrophobicity at different length scales is demonstrated by investigation of contact angle, contact angle hysteresis, droplet evaporation and propensity of air pocket formation as well as adhesive forces. The optimal structural parameters for superhydrophobicity and low static contact angle hysteresis, superior to natural plant leaves including Lotus, have been identified and provide a useful guide for development of biomimtetic superhydrophobic surfaces.
authors.affiliation: Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLB2), The Ohio State University, 201 West 19th Avenue, Columbus, Ohio 43210-1142. bhushan.2@osu.edu
authors.forename: Bharat
authors.initials: B
authors.lastname: Bhushan
authors.forename: Yong Chae
authors.initials: YC
authors.lastname: Jung
authors.forename: Adrian
authors.initials: A
authors.lastname: Niemietz
authors.forename: Kerstin
authors.initials: K
authors.lastname: Koch
mesh_terms: D000268:Adhesiveness; D040761:Biomimetic Materials / Q000737:chemistry*; D000070116:Lotus / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D014885:Waxes / Q000737:chemistry*
chemical_list: D014885:Waxes