Biomimetic Synthesis Of Silica Nanomaterials

In recent years, with the rapid development of science and technology of nano-materials, the preparation of nano-SiO2 gradually arouse people’s great attention. The traditional synthesis method of nano-SiO2 normally requires strong basic, high pressure or special equipment. It costs high energy consumption and serious pollution. The nature of the diatom cell wall, sponge spicules and some other plants have delicate nano silicon structures. These plants are able to control the precipitation of inorganic minerals from the molecular level under mild conditions. This is just to overcome the shortcomings of the traditional synthetic method of nano-SiO2 materials. Therefore the SiO2 nanoparticles biomimetic synthesis has become a hot spot.According to the method of biomimetic mineralization, this paper used the bacterial cellulose (BC) as the mineralization template and simulate plant mineralization mechanism under mild conditions. The effects of mineralization template, catalyst, silicon source on mineralization reaction were studied. Spectrophotometry was used to monitor the changes of the silica concentration in mineralization process. X ray diffraction (XRD) was used to observe the enrichment of silicon source at the surface of bacterial cellulose. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to analysis morphology of the products. The results showed that:the hydroxyl groups of bacterial cellulose is the main reaction group which play a key role in the mineralization process; diffferent ion environments have it’s own effects on biomimetic synthesis. When using NaNO3, the silification reaction is too quickly to form the ideal SiO2 nano-tubes. As for Na2HPO4, Na2SO4 and NH4Cl, the coagulation rate is low. Using Na2HPO4 as catalysator is the best choice, which could obtain the ideal structure. NH4Cl and Na2SO4 has low coagulation rate, so the mineralization products have thin pipe walls. It is found that the mineralization product has uniform morphology and space mesh structure under the conditions of pH=5,with TEOS and 2ml Na2HPO4 as catalyst.