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Anisotropic surfaces with micropillar- or micropillar/nanobump structures and anisotropic wetting behavior were fabricated. Structures were arranged as three parallel zones where the structure of the middle zone differed from that of the edge zones. The widths of the middle zones were increased systematically, and the effects of the middle zone structures and widths on the contact and sliding angles of water were investigated. Structures were fabricated on PP by injection molding. Microstructured mold inserts for injection molding were obtained by structuring aluminum foils with a microworking robot, and hierarchically structured mold inserts by anodizing the microstructured foils. It was possible to create surfaces where the microstructure in the middle zone was lower or higher than on the edges, or where the middle zone had only nanostructure or was unstructured. The behavior of water on the surfaces was characterized by measuring the dynamic contact angles and sliding angles parallel and perpendicular to the zones. Hydrophobic surfaces were achieved. With appropriate middle zone widths, clearly differing parallel and perpendicular contact angles were measured and elongation of droplets along the middle zones was detected.

A dynamic test method for the measurement of the underwater sliding properties of model boats has been developed. Surface-modified model boats were examined to assess how the surface wettability properties affect sliding. Along with the surface properties, the influence of the boat shape was considered. We studied various coatings in the contact angle range of 3–162[Formula: see text] with two model boat shapes. The hydrophobicity of the surfaces influenced the sliding speed of the model boat depending on the boat shape. The method is applicable to study sliding properties of model boats with different surfaces in variable flow conditions.

In this paper, the wettability properties of coatings with hierarchical surface structures and low surface energy were studied. Hierarchically structured coatings were produced by using hydrophobic fumed silica nanoparticles and polytetrafluoroethylene (PTFE) microparticles as additives in polyester (PES) and polyvinyldifluoride (PVDF). These particles created hierarchical micro–nano structures on the paint surfaces and lowered or supported the already low surface energy of the paint. Two standard application techniques for paint application were employed and the presented coatings are suitable for mass production and use in large surface areas. By regulating the particle concentrations, it was possible to modify wettability properties gradually. Highly hydrophobic surfaces were achieved with the highest contact angle of 165[Formula: see text]. Dynamic contact angle measurements were carried out for a set of selected samples and low hysteresis was obtained. Produced coatings possessed long lasting durability in the air and in underwater conditions.