Fabrication And Characterization Of Superhydrophobic Wood

The bionic superhydrophobic surface is a new field in the research of chemical model of biological systems. The superhydrophobic behavior of lotus leaf, etc. has provided the interesting natural phenomenon and practical basis for the fabrication of bionic superhydrophobic surface on different substrates. According to the ideas of bionic research, superhydrophobic wood surface was prepared by different ways. In detail, the micro and nano roughness was constructed on the wood surface, then low surface energy molecules was self-assembled on its surface, and the superhydrophobic wood was obtained finally. Superhydrophobic surface is a type of surface with large static water contact and small sliding angle, which presents an excellent waterproof property just like the lotus leaf and has a wide application such as microfluidics, anti-fog, anti-snow, anti-polltion, anticorrosion and antioxidation. Meanwhile, inorganic substance generated in situ can improve the lasting quality of wood, including anticorrosion, insect prevention, inflaming retarding, etc, which has a broad prospects. In this work, the chemical reaction process of micro-nano structure on wood surface and the reaction principle of interface between woods were studied. Moreover, the role of ornament on rough surface and the theory system of the preparation of bionic super-hydrophobic surface were researched as well.(1) Superhydrophobic wood surfaces were fabricated from potassium methyl siliconate (PMS) through a convenient and environment-friendly method. First, the wood sample was immersed in the PMS aqueous solution with electromagnetically stirring, and CO2was subsequently bubbled into the mixture until the pH value decreased to9. Then the wood sample was hold and concentrated in this solution for18h at room temperature, and then the wood sample was placed in vacuum drying oven at120℃for condensating of siloxane polymer. Finally, the superhydrophobic coating of polymethylsilsesquioxane was obtained on the wood surface. The effect of the PMS concentration on contact angle was discussed, and the optimal concentration has been obtained. Superhydrophobic wood surfaces were characterized by using a scanning electron microscope (SEM), energy dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TGA) and contact angle measurement. The result shows that the wetting behavior of wood transformed from hydrophilicity to superhydrophobicity.(2) Based on "lotus leaves effect", superhydrophobic wood surface can be fabricated by two category methods:(1) creating micro/nano structure surface roughness on wood surface through depositing flowerlike ZnO, rodlike ZnO and flowerlike CaCO3coatings; and (2) modifying the rough surface with stearic acid moleculors. The surface morphology of ZnO coatings on wood surface in different concentration of zinc acetate and different values of pH was characterized by scanning electron microscopy (SEM). The crystal form of CaCO3particles on wood surface obtained in different concentration of calcium trichloroacetate below75℃was characterized by X-ray diffraction (XRD). The effect of nano/micro structure on the preparation of superhydrophobic surface was analysed by using a commercial contact meter.(3) The BaCO3/Wood composites have been fabricated by two steps. First, the inorganic sediment inside and outside the wood was generated by the method of two step diffusion. Then superhydrophobic BaCO3/Wood composites were obtained by the modification of stearic acid, and then the properties of composites were characterized using SEM, TGA, FT-IR and WCA. Meanwhile, the physical and mechanical performances of superhydrophobic BaCO3/Wood composites have been tested, and the result shows that both of physical and mechanical performances have got considerable improvement.