Fabrication Of Hieraychical (Nano-Micro) Superhydrophobic Surfaces By Chemical Etching And Sol-Gel Technique

In the past few years, superhydrophobic surfaces with water contact angle larger than 150°have received a lot of research attention, due to their important applications in self-cleaning materials, microfluidic devices and biomaterials. Making the fabrication of superhydrophobic surface low-cost and controlable remains the main goal of recent study. In this paper, by the use of chemical etching and modification with material with low surface energy, we obtain superhydrophbic surfaces on the matrix of copper and aluminum. Here, by adding surfactant in etching agent, we improved traditional chemical etching technique. Meanwhile, we prepared superhydrophobic glass surface by sol-gel technique. Compared with traditional preparation method of aluminum sol, we did not use expensive, flammable and poisonous metal alkoxide, but chose cheap and easily available HNO3 as raw material. This method is environmental protecting, low-carbon and advantageous to the industrialized preparation of superhydrophobic surface.The copper wafer was etched by HNO3 solution containing cetyltrimethylammonium bromide (CTAB). Spherical micropits and nanosphere were formed on the etched surface. The etched surface was of superhydrophobicity with water contact angle 155±2.3°after silanization. The effect of different etching conditions on superhydrophobicity were investigated. Results showed that CTAB surfactant and ultrasonication had important effect on the formation of surface roughness and superhydrophobicity. XPS was used to characterize the silanizational surface, and results showed that the silicon surface was successfully modificated with 1H,1H,2H,2H-perfluorodecyltriethoxysilane. The etching mechanism of HNO3 solution containing CTAB under ultrasonication was investigated in this paper. And the proposed concept of bubble-assisted etching mechanism have potential significance to the theoretical reseach and industrializatin of superhydrophobic surface.Micropits and ladder-like structure were formed on the aluminum matrix after it was etched by SDBS/HCl solution The etched aluminum surface was of superhydrophobicity after fluoroalkylsilane modification. In the study of SDBS/HCl etching mechanism, on the basis of stacking fault etching mechanism, the effect of SDBS on the etching process and the superhydrophobicity was analysed. The measurement of different pH water contact angles on the aluminum surface showed that the superhydrophobic aluminum surface was of good corrosion resistance; the water contact angle changes of the aluminum surface which was placed for different time showed that the superhydrophobic aluminum surface was of good stability. The coatings of pine-needles-like structure were fabricated on glass surface by sol-gel technique. The superhydrophobic glass surface was obtained after fluorosilane modification. The as-prepared glass surface showed good superhydrophobicity after being heated for 24 h at 150℃or being exposed in air for 30 days. The measurement of different pH water contact angles on the surface showed that the superhydrophobic glass surface was of good corrosion resistance.