The Research Of Synthesis, Transfer And Adhesion Performance Of Carbon Nanotubes Array Based Dry Adhesive

Vertically aligned carbon nanotubes array(VACNTs) show a great potential in the application field of gecko-inspired dry adhesive because of its high aspect ratio, excellent mechanical property and the hierarchical micro-nano scale structure. This paper investigated the effect of the key processing factors during chemical vapor deposition on the morphologies of VACNTs. The silicon substrate used for VACNTs growth brings a lot of limitations for VACNTs applied as gecko-inspired dry adhesive such as weak interfacial bonding and worse flexibility. In order to resolve these problems, we proposed some methods to reduce the limitation resulted from the silicon substrate, with respect to the material transfer process and new growth process.The growth rate of VACNTs increases with the rising temperature of H2 pretreatment during CVD process, and the grown VACNTs show a better surface morphology with fewer defects. The height of VACNTs increases with the concentration of carbon source and the growth time. The adhesion test shows that shear adhesive strength of VACNTs increases with the height until a highest point on 22 N/cm2 and then decreases with the height of VACNTs. It is also found that after the first adhesive test, VACNTs got a tilted surface morphology and thus enhanced the adhesive strength for the second time test. With the repeat test increase, the adhesion strength decreased finally. The maximum shear adhesive strength of VACNTs can be achieved near 20 N/cm2, and the weights can be suspended for 96 min.With the combination of thermal oxidation separation and heating transfer process, VACNTs were transferred onto flexible polycarbonate substrate. The interfacial bonding strength was enhanced for 12 times and showed a good structural stability and outstanding flexibility. The shear adhesion property of both top transferred and bottom transferred VACNTs increased with the preload. When 16 N/cm2 preload was applied, the shear adhesion strength of top transferred and bottom transferred VACNTs can be around 2.8 N/cm2 and 5 N/cm2, respectively. The bottom transfer process show a better potential for transferred VACNTs dry adhesive.Develop a new structure of graphene/CNTs array composite grown on copper substrate by chemical vapor deposition. The scanning electron microscopy images show that CNTs bundles self-sustained on the graphene layer, which is a similar structure as gecko foot hairs. The nanoscratch test implies that the interfacial bonding strength between VACNTs and copper substrate is nearly 0.65 m N, which is 6.5 times higher than that between VACNTs and silicon substrate.