Study On The Preparation And Properties Of Biomimetic Superhydrophobic Surfaces

Wettability of a solid surface is one of important properties.Superhydrophobic surfaces have a water contact angle higher than150°and a low sliding angle (<10°). In recent decade, this field has received alot of scientific attention due to their important applications ranging fromself-cleaning to anti-icing and drag reduction.It is well known that a surface wettability depends on its chemicalcomposition and morphology. According to this point, various biomimeticsupehydrophobic surfaces have been fabricated by constructing specialhierarchical roughness on hydrophobic materials or modifying roughsurfaces with low free energy. However, most of the processes are verycomplicated and expensive, which are also fabricated in laboratory withsmall-scale. Herein, we proposed some smart routes to fabricate thebiomimetic superhydrophobic surfaces, showing good wettability andexcellent mechanical properties.In this thesis, two types of superhydrophobic surfaces based on siliconand glass substrates, have been fabricated smoothly.(1) A series of rough surfaces have been fabricated, depending ondifferent etching time of Cu/Ag-assisted chemical etching, subsequentlymodified with low surface energy materials. The prepared surfaces showhigh static contact angles more than150°and small sliding angles lowerthan10°. Meanwhile, the effect of etching time on the final morphologyis also discussed.(2) The fabrication of silica hollow micro-spheres through a carbontemplating route is also presented. Silica seeds are first deposited onto thesurface of carbon beads as a result of the hydrolysis and condensation oftetraethyl orthosilicate (TEOS) in a basic condition. Subsequent growthof silica seeds to nanoparticles with size of~40nm leads to the binarystructure, on which micro-spheres were decorated with nanoscale silicaparticles. Afterwards, the hollow micro-spheres were obtained bycalcinations process. The transparent superhydrophobic glass was obtained after modification of low surface energy materials, showing ahigh contact angle152°and a low sliding angle (<10°). It is found thatthe transmittance of superhydrophobic surfaces depends on the filmthickness and the optimal transmittance has reached as high as ninetypercent compared to that of pure glass.In addition, the comparisons of the quantity of frost formed onsuperhydrophobic surfaces and hydrophobic surfaces, which are based onaluminum. Furthermore, the effects of different water contact angles tofrosty status on aluminum surfaces were investigated. The result showsthat the better the performance of surface hydrophobicity, the less thequantity of the frost.