Double-scale roughness and superhydrophobicity on metalized Toray carbon fiber paper

A simple, inexpensive route for the fabrication of a superhydrophobic metal surface is described. Carbon-carbon composite paper (Toray TGP-H) is electroplated with copper. The copper layer is made hydrophobic by self-assembling a monolayer of dodecanethiol. The surface topography required to induce superhydrophobic behavior is achieved by varying the plating bath composition (Cl-, PEG, and SPS additives) and the time of deposition (effective thickness of the Cu layer). The surface morphology created by the original arrangement of the carbon fibers in the Toray paper (diameter 8 microm, spacing 30 microm) does not produce superhydrophobic behavior. This is true for both continuous and incomplete copper coatings. Truly superhydrophobic behavior (large contact angles, 160-165 degrees, and very small contact angle hysteresis, 2 to 3 degrees) is achieved when a continuous copper layer is deposited on the carbon fibers and also a second micrometer-range roughness is developed as a result of the formation of small copper crystallites (size approximately 1 microm).