Figure 6. Typical biological materials with superwettability and corresponding multiscale structures. (a) Lotus leaves demonstrate low adhesive, superhydrophobic, and self-cleaning properties, due to randomly distributed micropapillae covered by branch-like nanostructures. (b) Rice leaf surfaces possess anisotropic superhydrophobicity arising from the arrangement of lotus-like micropapillae in one-dimensional order. (a and b) Reproduced with permission from ref 7. Copyright 2002 Wiley. (c) Butterfly wings exhibit directional adhesion, superhydrophobicity, structural color, self-cleaning, chemical sensing capability, and fluorescence emission functions due to the multiscale structures. Reproduced with permission from ref 45. Copyright 2007 American Chemical Society. (d) Water strider legs have robust and durable superhydrophobicity arising from directional arrangements of needlelike microsetae with helical nanogrooves. Reproduced with permission from ref 46. Copyright 2004 Nature Publishing Group. (e) Mosquito compound eyes demonstrate superhydrophobic, antifogging, and antireflection functions due to HCP microommatidia covered by HNCP nanonipples. Reproduced with permission from ref 47. Copyright 2007 Wiley. (f) Poplar leaves possess superhydrophobic and antireflection properties originating from dense hairs with the hollow fibrous structure. Reproduced with permission from ref 48. Copyright 2011 The Royal Society of Chemistry. (g) Gecko feet present superhydrophobic, reversible adhesive, and self-cleaning functions due to the aligned microsetae splitting into hundreds of nanospatulae. Reproduced with permission from ref 49. Copyright 2012 The Royal Society of Chemistry. (h) Red rose petals exhibit superhydrophobicity with high adhesion and structural color arising from periodic arrays of micropapillae covered by nanofolds. Reproduced with permission from ref 31. Copyright 2008 American Chemical Society. (i) Salvinia leaves demonstrate the superhydrophobic and air-retention properties due to the Salvinia Effect. Reproduced with permission from ref 50. Copyright 2010 Wiley. (j) Fish scales present drag reduction, superoleophilicity in air, and superoleophobicity in water due to oriented micropapillae covered by nanostructures. Reproduced with permission from ref 33. Copyright 2009 Wiley. (k) Clam shell shows low adhesive superoleophobicity underwater arising from the surface multiscale structures and special chemical composition. Reproduced with permission from ref 51. Copyright 2012 Wiley. (l) Peanut leaves exhibit high adhesive superhydrophobicity and fog capture properties originating from the special surface multiscale structures and chemical composition. Reproduced with permission from ref 52.

Nature is a school for scientists and engineers. After four and a half billion years of stringent evolution, some creatures in nature exhibit fascinating surface wettability. Biomimetics, mimicking nature for engineering solutions, provides a model for the development of functional surfaces with special wettability. Recently, bio-inspired special wetting surfaces have attracted wide scientific attention for both fundamental research and practical applications, which has become an increasingly hot research topic. This Critical Review summarizes the recent work in bio-inspired special wettability, with a focus on lotus leaf inspired self-cleaning surfaces, plants and insects inspired anisotropic superhydrophobic surfaces, mosquito eyes inspired superhydrophobic antifogging coatings, insects inspired superhydrophobic antireflection coatings, rose petals and gecko feet inspired high adhesive superhydrophobic surfaces, bio-inspired water collecting surfaces, and superlyophobic surfaces, with particular focus on the last two years. The research prospects and directions of this rapidly developing field are also briefly addressed (159 references).

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Oil/water separation is a worldwide challenge. Learning from nature provides a promising approach for the construction of functional materials with oil/water separation. In this contribution, inspired by superhydrophobic self‐cleaning lotus leaves and porous biomaterials, a facile method is proposed to fabricate polyurethane foam with simultaneous superhydrophobicity and superoleophilicity. Due to its low density, light weight, and superhydrophobicity, the as‐prepared foam can float easily on water. Furthermore, the foam demonstrates super‐repellency towards corrosive liquids, self‐cleaning, and oil/water separation properties, possessing multifunction integration. We expect that this low‐cost process can be readily and widely adopted for the design of multifunctional foams for large‐area oil‐spill cleanup.