Bioinspired Special Wettability Surfaces: From Fundamental Research to Water Harvesting Applications

Abstract

Nowadays, the pollution of water has become worse in many parts of the world, which causes a severe shortage of clean water and attracts widespread attention worldwide. Bioinspired from nature, i.e. spider silk, cactus, Namib desert beetle, Nepenthes alata, special wettability surfaces have attracted great interest from fundamental research to water-harvesting applications. Here, recently published literature about creatures possessing water-harvesting ability are reviewed, with a focus on the corresponding water-harvesting mechanisms of creatures in dry or arid regions, consisting of the theory of wetting and transporting. Then a detailed account of the innovative fabrication technologies and bionic water-harvesting materials with special wetting are summarized, i.e. bio-inspired artificial spider silk, bio-inspired artificial cactus-like structures, and bio-inspired artificial Namib desert beetle-like surfaces. Special attentions are paid to the discussion of the advantages and disadvantages of the technologies, as well as factors that affect the amount of water-harvesting. Finally, conclusions, future outlooks and the current challenges for future development of the water-harvesting technology are presented and discussed.

Micro‐/Nanostructured Interface for Liquid Manipulation and Its Applications

“…a‐d) Different wetting behaviors of solid surface: a) Young's model, b) Wenzel's model, c) Cassie's model, and d) Furmidge model. a–d) Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

“…Water collection is of great significance in alleviating water shortage and water pollution, especially when the approach can be cost‐effective and facile. Nature offered many brilliant examples in this aspect, since many creatures possess special body structures that could collect condensed water directly from humid air, especially those creatures surviving in drought areas, such as cactus , Namib desert beetle and Nepenthes alata . Water collection carried out by their special biological structures is spontaneous, effective and with no cost.…”

Tailoring the Morphology of Responsive Bioinspired Bicomponent Fibers

“…The amphiphilic nature of the produced s‐b‐s and coaxial bead‐on‐string fibers together with the thermoresponsivity of PNiPAAm makes these fibers promising materials for applications as actuators or for water harvesting, respectively . Figure a–d demonstrates the reversible buckling of PNiPAAm/P(MMA‐ co ‐BMA) s‐b‐s fibers upon cooling to 0 °C and subsequent heating to 40 °C.…”

“…In this approach, a polymer solution is coated onto a supporting fiber, which further on breaks up into droplets driven by Rayleigh instability. Fibers with coaxial bead‐on‐string morphology are very promising materials for water harvesting applications, which demands for the development of efficient large‐scale production methods …”

“…The use of Raman imaging and atomic force microscopy (Raman/AFM) is shown as a powerful method for unambiguous characterization of complex bicomponent fiber morphologies. The combination of a thermoresponsive (PNiPAAm) and a “neutral” material (P(MMA‐ co ‐BMA)) in fibers of different morphologies, produced in a facile upscalable process, opens the way for interesting applications, e. g., as actuators or for water harvesting …”