The anti-biofouling effect against barnacles of a super-hydrophobic and high-oleophobic surface of treated aluminum

The effect of the low apparent solid surface energy of a specially engineered substrate on the settlement of barnacles was studied. To obtain an aluminum (Al) plate with low apparent solid surface energy, a plate was roughened by sandblasting and electrolytic chemical etching, and then coated with a chemically adsorbed monolayer (CAM) containing a fluorocarbon group. The plate was characterized by means of fluid contact angle measurements and a barnacle settlement test. The water contact angle (WCA) was 152°, and the oil contact angle of n-hexadecane (OCA) was 121°. The surface of the plate thus displayed super-hydrophobicity and high-oleophobicity. In addition, the wettability of this surface was evaluated, in terms of calculated apparent total solid surface energy, as approximately 1.6 mN/m. In laboratory experiments, barnacles did not settle on the plate when exposed for 7 days. In comparison to controls using a variety of untreated and partially treated plates, this indicates that the surface treated to have low apparent solid surface energy can have an anti-biofouling effect, which may be explained by a combination of effects of relief and material.