Fabrication and application of reversibly switchable surfaces: Super-non-wetting to super-wetting: A critical review

Wettability is an important and complex property of solid surfaces. In recent years there has been much interest in novel wetting behavior and its adaption for use in commercial applications. One area that has attracted significant attention is that of switchable wettability, specifically the controlled and reversible conversion between superhydrophobic and superhydrophilic wetting states. Targeted drug delivery, water-harvesting, and antireflective, water-proofing and liquid self-transportation coatings are just a few examples where such switchable or smart surfaces are finding applications. As has been demonstrated conclusively by the plethora of studies in the area, wetting behavior is controlled not only by the chemical composition of a surface, but also by its morphology. The combining of controlled changes in surface chemistry with the introduction of surface structures has been shown to be an effective technique for providing a switch between extreme wetting phenomena. In this review, recent progress as well as current and future trends in the area of smart surfaces are outlined. Given the importance of introducing geometrical structures in generating such systems, the effect of micro-/nano-/micro-nano-binary surface roughness is highlighted.