White Roman Goose Feather-Inspired Unidirectionally Inclined Conical Structure Arrays for Switchable Anisotropic Self-Cleaning.

White Roman goose (Anser anser domesticus) feathers, comprised of oriented conical barbules, are coated with gland-secreted preening oils to maintain a long-term nonwetting performance for surface swimming. The geese are accustomed to combing their plumages with flat bills in case they are contaminated with oleophilic substances, during which the amphiphilic saliva spread over the barbules greatly impairs their surface hydrophobicities and allows the trapped contaminants to be anisotropically self-cleaned by water flows. Particularly, the superhydrophobic behaviors of the goose feathers are recovered as well. Bioinspired by the switchable anisotropic self-cleaning functionality of white Roman geese, superhydrophobic unidirectionally inclined conical structures are engineered through the integration of a scalable colloidal self-assembly technology and a colloidal lithographic approach. The dependence of directional sliding properties on the shape, inclination angle, and size of conical structures is systematically investigated in this research. Moreover, their switchable anisotropic self-cleaning functionalities are demonstrated by Sudan blue II/water (0.01%) separation performances. The white Roman goose feather-inspired coatings undoubtedly offer a new concept for developing innovative applications that require directional transportation and the collection of liquids.

Self-Assembly of Hemimyzon Formosanus-Inspired Crescent-Shaped Nanosucker Arrays for Reversible Adhesion.

Hemimyzon formosanus, a species of ray-finned fish, makes use of crescent-shaped abdominal suckers for adhering to irregular, rough, and slippery gravel in fast-flowing headwaters and minor tributaries. Bioinspired by the adhesion characteristics, two-dimensional non-close-packed colloidal crystals are self-assembled and serve as templates to pattern crescent-shaped shape memory polymer-based nanostructure arrays. By the manipulation of the configuration of nanosuckers through applying common solvent stimulations, the corresponding adhesion performances on glass, sandpaper, or even porcine kidney surfaces can be switched instantaneously and reversibly under ambient conditions. The biomimetic nanostructures indicate possible solutions to a variety of challenges, such as wound nursing, and so on.