Temperature-tunable wettability on a bioinspired structured graphene surface for fog collection and unidirectional transport

Abstract

We designed a type of smart bioinspired wettable surface with tip-shaped patterns by combining polydimethylsiloxane (PDMS) and graphene (PDMS/G). The laser etched porous graphene surface can produce an obvious wettability change between 200 °C and 0 °C due to a change in aperture size and chemical components. We demonstrate that the cooperation of the geometrical structure and the controllable wettability play an important role in water gathering, and surfaces with tip-shaped wettability patterns can quickly drive tiny water droplets toward more wettable regions, so making a great contribution to the improvement of water collection efficiency. In addition, due to the effective cooperation between super hydrophobic and hydrophilic regions of the special tip-shaped pattern, unidirectional water transport on the 200 °C heated PDMS/G surface can be realized. This study offers a novel insight into the design of temperature-tunable materials with interphase wettability that may enhance fog collection efficiency in engineering liquid harvesting equipment, and realize unidirectional liquid transport, which could potentially be applied to the realms of microfluidics, medical devices and condenser design.

Experimental and computational studies of a graphene oxide barrier layer covalently functionalized with amino acids on Mg AZ13 alloy in salt medium

“…Further, the alloy active sites are passivated by the GO functionalized materials. [28][29][30][31][32] Fig. 6B shows that impedance of epoxy coating Mg alloy R ct value is decreased to 24 U and C dl value is increased to 9.2228 mF which may indicate that Mg alloy undergoes corrosion due to epoxy coating peel off from alloy surface.…”

Bioinspired materials for water-harvesting: focusing on microstructure designs and the improvement of sustainability

“…On the wedge-shaped patterned surface, the generated Laplace pressure allows the droplet to move from the wedge-shaped tip to the wedge-shaped wide end. [85][86][87][88] Song et al 89 combined PDMS and graphene (PDMS/G) to design a smart surface with a sharp shape that could be used for water collection, proving that the geometric pattern and wettability coordination were the key to the directional movement of the droplets. They used spin coating to prepare a superhydrophobic PDMS/G layer on a superhydrophilic glass substrate.…”

“…For example, the deposition speed of water droplets on hydrophilic surfaces is very fast but due to the low contact angle, it is easy to form a water film and hinder the next round of water collection. 89 Water droplets are spherical on the hydrophobic surface, which are easy to coalesce with the surrounding droplets to form large droplets but the nucleation speed is relatively slow. Three-dimensional composite structures greatly improve the fog collection efficiency by integrating the advantages of these mechanisms.…”

“…The hydrophilic-superhydrophobic surface with tip patterns exhibited the highest fog collection efficiency. Reproduced with permission 89. Copyright 2018, Royal Society of Chemistry.…”

The Design of Hydrophilic Nanochannel‐Macrostripe Fog Collector: Enabling Wicking‐Assisted Vertical Liquid Delivery for the Enhancement in Fog Collection Efficiency

“…[ 10,11 ] Recently, the novel collector design such as fog collectors incorporating hydrophilic/hydrophobic patterns or harp‐like design has shown better fog collecting performances by achieving continuous directional liquid transport. [ 12–19 ] In addition, new surfaces have significantly improved fog collection performances by mimicking characteristics of species in nature. [ 20–22 ] The common examples of the inspiration for the fog collector design include the Namib desert beetles' shell, [ 23,24 ] spiky leaves of cacti, [ 25,26 ] and mesh‐like spider webs' knots.…”