title: Orthogonal, three-component, alkanethiol-based surface-chemical gradients on gold.
abstract: An orthogonal surface-chemical gradient composed of self-assembled monolayers on gold has been prepared by successive, controlled immersions in orthogonal directions into dilute solutions of dodecanethiol and perfluorododecanethiol. The resulting two-component orthogonal gradient in surface coverage was backfilled with 11-mercaptoundecanol, leading to a two-directional, three-component surface-chemical gradient. Water and hexadecane show distinctly different wetting behaviors on the gradient surface because of the differences in the hydrophobic and oleophobic natures of the three different constituents. These results are correlated with the chemical composition maps of the surface obtained by X-ray photoelectron spectroscopy. The homogeneity and the ordering of the self-assembled monolayer were investigated by dynamic water contact angle measurements and polarization-modulation infrared reflection-absorption spectroscopy.
authors.affiliation: Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland.
authors.forename: Eva
authors.initials: E
authors.lastname: Beurer
authors.forename: Nagaiyanallur V
authors.initials: NV
authors.lastname: Venkataraman
authors.forename: Antonella
authors.initials: A
authors.lastname: Rossi
authors.forename: Florian
authors.initials: F
authors.lastname: Bachmann
authors.forename: Roman
authors.initials: R
authors.lastname: Engeli
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Spencer
mesh_terms: D006046:Gold / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D013438:Sulfhydryl Compounds; D006046:Gold