Manipulation of the Wettability of Surfaces on the 0.1- to 1 -Micrometer Scale Through Micromachining and Molecular Self-Assembly

Abstract

Micromachining allows the formation of micrometer-sized regions of bare gold on the surface of a gold film supporting a self-assembled monolayer (SAM) of alkanethiolate. A second SAM forms on the micromachined surfaces when the entire system—the remaining undisturbed gold-supported SAM and the micromachined features of bare gold—is exposed to a solution of dialkyl disulfide. By preparing an initial hydrophilic SAM from HS(CH₂)₁₅COOH, micromachining features into this SAM, and covering these features with a hydrophobic SAM formed from [CH₃(CH₂)₁₁S]₂, it is possible to construct micrometer-scale hydrophobic lines in a hydrophilic surface. These lines provide new structures with which to manipulate the shapes of liquid drops.