Biomimetic Synthesis Of Ordered Mesoporous Silica Thin Films And Their Assembly Chemistry

To satisfy the application demands of photochromism camouflage and detection of biologic and chemical threat agents, ordered mesoporous silica thin films were prepared by a biomimetic synthesis method and modified with organsilane based on the biomineralization mechanism of nacre in shell. The assemblies and properties of active molecules in mesoporous silica thin films were studied, and the technical projects and feasibilities of the both applications were discussed.The dynamic analysis of microstructure of the nacre from the abalone with different shell ages has been investigated systematically for the first time. It is observed that some changes happen to the preferential orientation of aragonite crystals in the nacre, which is very important for further understanding the biomineralization process and instructing the biomimetic synthesis of materials. As a result, ordered mesoporous silica thin films were synthesized by evaporation-induced self-assembly process. The influencing factors and controlling mechanism of mesoporous structures and pore sizes were studied detailedly, and the technical problems of ordered degree and pore sizes adjusting of mesoporous films were solved. In particular, the effect of sol aging and its crucial action were investigated under the direction of the dynamic controlling view of biomimetic synthesis, and the theories of apparent mass fractal dimension and surfactant packing parameters were introduced to explain the changes of structure parameters in the synthetic process.According to the controlling mechanism of mesoporous structures and pore sizes of pure silica thin films, mesoporous silica thin films with high amino-groups content have been directly synthesized by co-condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane, and the mesoporous surface was modified successfully with organosilane. The resultant thin films have preferable thermal stability, and the inner surface coverage of amino-groups is up to 3.4 amino-groups per nm~2, which is very useful and promising for incorporating inorganic anions and biomolecules into the mesoporous silica thin films.Subsequently, molybdenum polyoxometalate and cytochrome c were assembled into the amino-functionalized mesoporous silica thin films. After immobilization of active molecules, the ordered structures of mesoporous films and the molecular structures and activities of active molecules are still retained, which are attributed to the stable inorganic-framework, appropriate pore sizes and functional modification of mesoporous films.It is a very important innovation that the ordered mesoporous silica thin films are applied to the regions of photochromism camouflage and detection of biologic and chemical threat agents in this paper. Based on the forementioned researches including synthesis, modification and assembly, the feasibility of monochromatic change was testified, and the new photochromic mechanism of composite system was proposed, and the problems for designing multicolor and patterns were solved. Through the investigations of electrochemistry behavior and sensing performance of active molecules on mesoporous films-modified electrodes, the biosensor for detection of organophosphorus pesticides was developed successfully, and the new pathway for detection of multi biologic and chemical threat agents has been suggested.