Fabrication Of Three-dimensional Ordered Macroporous SiO₂ By Polystyrene Colloidal Crystal Template Method And Its Application

Three-dimensional ordered macroporous （ 3DOM ） material have highly ordered inverse opal structure. The special structure is potential candidates for useful application in fields, such as optical, sensors, catalysis and batteries and so on. This paper aims to use the simple and efficient way to preparation of the 3DOM SiO₂ by polystyrene （PS） colloidal crystal method. And then study its application in catalysis.The quality of colloidal crystal template decided the quality of 3DOM materials. And the quality of colloidal crystal template depends on the monodisperse of polystyrene microspheres. We have prepared monodisperse PS microspheres by dispersion polymerization, with the size of about 700nm. Also we prepared monodisperse PS microspheres with the size of about 200nm by emulsion polymerization, and prepared monodisperse PS particles modified by methyl acrylate （ MAA ） with the size of 150-300nm by emulsifier-free emulsion polymerization.The PS and modified PS colloidal crystals were assembled by the evaporation self-assembly method. We explored the effect of microspheres monodisperse, solution concentration, humidity, container and hydrophobicity groups on the microsphere surface when the colloidal crystals assembly. Then we further improved the assemble mechanism of evaporation self-assembly.We have prepared of 3DOM SiO₂ by using sol-gel method and evaporation self-assembly co-deposition method. It was found that the3DOM SiO₂ material which was prepared by the evaporation self-assembly co-deposition method has many advantages, such as highly filling rate, small shrinkage, overall order and thickness controllable. The 3DOM SiO₂ fabricated by the modified PS colloidal crystals with the filling rate of 66.7% and the shrink rate of 4%. At the same time, the 3DOM SiO₂ prepared by the evaporation self-assembly have a larger surface area than by Sol-gel method.We tried to support phosphotungstic acided on the 3DOM SiO₂ fabricated by modified PS colloidal crystals. But the load rate is not high. Then we prepared overall ordered 3DOM material by the ternary co-deposition method and found that the Keggin structure of phosphotungstic acid is not destroyed in the process of roasting. While the materials appear stratification, the upper structure with regular uniform pores contains a large number of phosphotungstic acid and a small amount of SiO₂, and the lower strucutre without any pores contains only pure SiO₂.