| Colloidal crystals were paid significant attentions due to their applications in the fields of photonic crystal, catalyst, chromatographic analysis, biological materials, and membrane reactor etc. Self-assembly of colloidal microspheres had emerged as a kind of high-efficiency and low-cost method for fabricating colloidal crystal. The self-assembly methods mainly included the solvent evaporation, electrophoretic deposition, deposited at the gas-liquid interface, etc. In recent years, the crystal growth and crystal structure were studied by the way of using the binary colloidal crystals as structure templates, and the binary colloidal crystals with long-range order structure were obtained by controlling experimental conditions. On the basis of summarizing the previous research works on colloidal crystals, this paper mainly focused on three aspects as following.(1) Spherical SiO2 monodisperse colloidal particles with different particle size were prepared by improved Stober method, the effects of TEOS concentration, water concentration, ammonia concentration, solvent type and reaction temperature on the diameter and the monodispersity of spherical SiO2 colloidal particles were explored. The study showed that the size of spherical SiO2 monodisperse colloidal particles increased when the TEOS concentration and ammonia concentration increased. Monodispersity of spherical SiO2 colloidal particles were best when the concentration of TEOS was 0.3M and the concentration of ammonia was 1.0M. The size of spherical SiO2 monodisperse colloidal particles increased at first then decreased when the water concentration increased. Monodispersity of spherical SiO2 monodisperse colloidal particles were best when the concentration of water was 5.0M. The size of spherical SiO2 monodisperse colloidal particles decreaseed when we added methyl alcohol to alcohol solvent. The size of spherical SiO2 monodisperse colloidal particles decreased when we increased the reaction temperature. Monodispersity of spherical SiO2 monodisperse colloidal particles was best when the reaction temperature was 40 ℃. Moreover, the interfacial electrical properties of spherical SiO2 monodisperse colloidal particles with different size were measured to get a sight of isoelectric point(IEP).(2) Spherical SiO2 monodisperse colloidal particles were surface-modified with silane coupling agent Methacryloxypropyltrimethoxysilane(KH-570) by chemical method and self-assembled to colloidal crystal at the air-water interface. The optimum mass of KH-570 was 26.1% of the mass of the spherical SiO2 monodisperse colloidal particles. The effects of suspension concentration, type of dispersing agent, size of spherical SiO2 monodisperse colloidal particles and drying temperature were explored. Study showed that methanol were the optimum dispersing agent. The Bragg diffraction peak intensity colloidal crystals was maximum when the suspension concentration was 2wt% and drying temperature was 40℃. The Bragg diffraction peak position was changed when we used different size of spherical SiO2 monodisperse colloidal particles.(3) Colloidal crystals were fabricated by horizontal deposition method with 240nm spherical SiO2 monodisperse colloidal particles.The Effects of type of dispersing agent, suspension concentration and drying temperature were explored. Study showed that water was the optimum dispersing agent. The ordering of colloidal crystals were increased when we increased the concentration of suspension and drying temperature properly. The Bragg diffraction peak intensity of colloidal crystals was maximum when the suspension concentration was 5wt% and the drying temperature was 50 ℃. Characterization by SEM showed that spherical SiO2 monodisperse colloidal particles arrayed to hexagonal close packing form. Lower temperature was beneficial to assemble colloidal microspheres into the form of cubic close packing.(4) Tried to build binary colloidal crystals with structure like ion crystal with horizontal deposition method. Effects of diameter ratio of two different spherical SiO2 monodisperse colloidal particles, particle number ratio and drying temperature were explored. Study showed that Bragg diffraction peak intensity of binary colloidal crystals increased slightly when diameters of small colloidal microspheres were increased. The tranimission spectra had two obvious peaks under the condition of Ds/L=0.539, explaining that two kinds of colloidal microspheres were ordered arrangement. The optimum particle number ratio was Ns/L=2. Lower temperature was advantageous to the two kinds of colloidal microspheres assembled into an orderly binary colloidal crystal. |
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