Liquid Nanostripes

Abstract

Equilibrium wetting of ethanol, a volatile liquid, onto chemically patterned nanostripes has been investigated using noncontact atomic force microscopy (AFM). The chemical patterns, generated by a conducting AFM tip, are composed of COOH terminated “wetting” regions and ${\mathrm{CH}}_3$ terminated “nonwetting” regions. Controlled amounts of ethanol, from the vapor phase, condense on the COOH stripes and their shape is imaged in situ versus their width ($70<w<300\mathrm{nm}$). The measured profile shapes at saturation and their $w^{1/2}$ height dependence are well described by density functional theory with dispersive, nonretarded potentials.