Biofouling control by superhydrophobic surfaces in shallow euphotic seawater

Highly water repellent coatings known as superhydrophobic (SH) are related to surfaces with contact angles above 150 degrees and a very small hysteresis. Among many practical needs to which this property can be devoted, a very interesting field where the SH coating technology can be employed is represented by the protection of hulls in seawater environments from the biofouling colonization. The absence of toxic materials in the final product and in the preparation stage holds to preferable bio-compatible coatings, basing the action on low surface energy exerting physical prevention of bioadhesion of colonizing organisms. In this work we report on field tests of a superhydrophobic 'green' coating on aluminum and glass substrates in real seawater mesocosms conditioned/not conditioned by the natural photoperiod and the photobiology development. In particular, the performance, durability and fouling removability of the here tested SH coating is evaluated with immersions focusing on two time scales (days and weeks), emphasizing the role of conditioning film and initial biological slimes formation. Implications of results here obtained on ship hulls protection and indications for future investigations to be held are discussed. (C) 2014 Elsevier B.V. All rights reserved.