title: Hierarchical silicon etched structures for controlled hydrophobicity/superhydrophobicity.
abstract: Silicon surface hydrophobicity has been varied by using silane treatments on silicon pyramid surfaces generated by KOH anisotropic etching. Results demonstrated that by altering the surface hydrophobicity, the apparent contact angle changed in accord with the Wenzel equation for surface structures with inclined side walls. Hierarchical structures were also constructed from Si pyramids where nanostructures were added by Au-assisted electroless HF/H2O2 etching. Surface hydrophobicity and superhydrophobicity were achieved by surface modification with a variety of silanes. Stability of the Cassie state of superhydrophobicity is described with respect to the Laplace pressure as indicated by the water droplet meniscus in contact with the hierarchical structures. The contact angle hysteresis observed is also discussed with respect to water/substrate adhesion.
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332-0100, USA.
authors.forename: Yonghao
authors.initials: Y
authors.lastname: Xiu
authors.forename: Lingbo
authors.initials: L
authors.lastname: Zhu
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Hess
authors.forename: C P
authors.initials: CP
authors.lastname: Wong
mesh_terms: D016880:Anisotropy; D006858:Hydrofluoric Acid / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D006878:Hydroxides / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D015233:Models, Statistical; D017680:Potassium Compounds / Q000737:chemistry*; D011312:Pressure; D012821:Silanes / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013379:Substrate Specificity; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D006878:Hydroxides; D017680:Potassium Compounds; D012821:Silanes; D014867:Water; D006861:Hydrogen Peroxide; D006858:Hydrofluoric Acid; C029943:potassium hydroxide; D012825:Silicon