Wetting properties of silicon films from alkyl-passivated particles produced by mechanochemical synthesis.

A facile and efficient method using high energy ball milling (HEBM) to produce surfaces with a static and advancing contact angle in the superhydrophobic regime consisting of alkyl-passivated crystalline silicon particles is described. Deposition of the functionalized silicon material forms stable films on a variety of surfaces due to strong hydrophobic interactions between the individual particles. The process offers the ability to control the particle size from a micro-scale to a nano-scale region and thus to tune the surface roughness. Because of changing surface morphology and the decreasing surface roughness of the films due to the increasing milling times the static and dynamic contact angles follow a polynomial function with a maximum dynamic advancing contact angle of 171 degrees. This trend is correlated to the commonly used Wenzel and Cassie-Baxter models.