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The ice friction behavior of various microtextured polymer surfaces was studied with respect to ice temperature and applied load using a customized linear tribometer. Similar micropillar patterns were replicated on polypropylene and two rubber compounds, and when hierarchical micro–micro textures were present, all the materials exhibited superhydrophobicity. Taller protective micropillars were shown to be crucial for protecting the smaller microtextures from abrasive wear. The mechanical properties of the polymers affected the sliding friction of the microtextured surfaces on ice. High loading of hierarchical textures on rigid polypropylene or operation near the ice melting point tended to increase its adhesion tendency or resisting behavior. The sliding performance of the hard and soft rubber compounds was temperature-dependent, and the texture on the soft rubber influenced the sliding friction differently depending on the ice temperature. Consequently, textural modifications of the sliding surface enabled a certain degree of control over the sliding friction behavior on ice.

The fundamental understanding of the icephobic performance of two model superhydrophobic surfaces (lotus and petal surfaces) is important for many industrial applications. The effect of wettability and surface energy on ice adhesion has recently received attention. However, the verification of icephobicity is typically carried out with a single observation method. For this study, rough modified rod-coated surfaces, structured polymer surfaces and nine smooth surfaces with tunable wettability were fabricated. Combining several observation techniques of icephobicity indicate that petal and lotus surfaces lose their superhydrophobicity, being less useful for ice repellency due to poor humidity tolerance in condensation conditions. The ice adhesion of rough surfaces enhanced with increasing hydrophobicity. The increased interface area leads to a reduction of the icephobic performance. The stress concentrator on the lotus surface was better than on the petal surface. In addition, the role of dynamic wettability on ice adhesion was checked. Smooth hydrophobic surfaces were found to be better icephobic materials compared to rough surfaces. The intrinsic surface energy of smooth surfaces is significantly linear with the ice adhesion. High freezing delay times were found for smooth low-density polyethylene resin and fluorinated surfaces.

Structural hierarchy of polymer surfaces has been of central interest due to its diverse surface functionalities. However, the research on hierarchically structured polymer surfaces has been focused on planar surfaces even though applications may also be variously curved. This study demonstrates the fabrication of curved rigid polymer surfaces with precisely controlled hierarchical microstructures. The surface structuration was made on an aluminum foil with a microworking robot, and polypropylene replicas were produced by injection molding. Depending on the mold structuration procedure, the curved mold can have either radially or vertically oriented structures. Both convex and concave curvatures were here applied to spherically and cylindrically curved surfaces. A simple structure protection technique was applied to support the structures during mechanical bending of the foil. The planar hierarchically microstructured polypropylene surfaces were characterized to exhibit superhydrophobicity, and similar structures were obtained on the curved surfaces. Introducing the curvature to the hierarchically structured surfaces may further widen the applicability of functionalized polymer surfaces.

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.