Research On The Fabrication Of Biomimetic Multifunctional Superhydrophobic Surfaces

Due to their excellent water repellency, superhydrophobic surfaces have arousedintensive interest. Inspired from the self-cleaning lotus leaf, a great manysuperhydrophobic surfaces have been obtained according to the rule of combiningmicroscopic structures with low surface energy materials. And the various elaboratestructure endow the surfaces many other properties, such as structural color,anisotropy, optical transparency and so on. Moreover, originating from the waterprevention, the surfaces may earn extra properties, such as anti-snow, anti-icing,bacteria-proof, drag reduction, anti-corrosion and so on. Accordingly,superhydrophobic surfaces have gradually become ones of many functions. In thiswork, we mainly focus on two kinds of mulifunctional superhydrophobic surfaces: theones with sliding anisotropy and structural color.Rice leaves with anisotropic sliding properties have the ability to directionallycontrol the movement of water microdroplets. However, the reported anisotropicwetting surfaces are mainly limited to the static wetting without dynamic behavior.By careful observation, we found groove arrays on rice leaves, whose dimensions aremuch greater than those of the gratings widely adopted for anisotropic wetting study.Based on the classical two-stage model and the groove structure, a new three-levelmodel including macrogrooves, micropapilla and nanostructures, is proposed tointerpret the anisotropic sliding behavior. According to this rule, artificial rice leavesare prepared by photolithography, PDMS imprinting, and micro/nanostructure coating.Then, the superhydrophobicity and the sliding anisotropy were investigated. Further, anew testing method, curvature-assisted droplet oscillation, is also developed tocharacterize the dynamic behaviors. Finally, we make theoretical simulations for the oscillation test to achieve a quantitative illustration. It is demonstrated from the testsabove that we have reproduced the biological structure and function. These results arebeneficial to the design and fabrication of controllable biomimetic surfaces.Recently, butterfly wing and rose petal with unique water-repellency and brightappearance have attracted increasing attention. It is reported that the highly orderedmicro-/nanostructures plays a vital role in achieving the colorful superhydrophobicity.However, only a few attempts have been realized due to the technical challenge in thefabrication of periodic and well-defined textures in large area. Moreover, studies onthe emerging graphene materials mainly focus on the photoelectronic performance,but have not on its surface features yet. In this work, two-beam laser interference wasutilized to produce periodic grating structures and to simultaneously remove theoxygen groups on the graphene oxide films, thus created hierarchical structures withlow surface energy lead to the structural color and water prevention. The simple andfacile one-step method provides an effective approach to the functionalsuperhydrophobic surfaces.To sum up, bio-inspired from the natural creatures with excellentsuperhydrophobicity, we prepared surfaces with biomimetic structures via simple yetefficient methods. It is indicated that we have realized the superhydrophobic surfacewith sliding anisotropy and the one with structural color after performance testing andwetting state analysis. Furthermore, our research will be helpful in the understandingof the superficial physical and chemical properties of graphene.