Morphology research on self-assembly of SiO₂ colloidal crystals

Atomic force microscope (AFM) was used as a main observation tool to study the effect of three self-assembly ways of SiO₂ colloidal crystals: free sedimentation, filtration, and solvent evaporation. The influences of surface potential of monodispersed silica particles, solvent composition and temperature were investigated, and surface potential was proved to be the most significant factor in the assembling process. The AFM images identified the optimized assembly conditions in the study. Compared with the other two ways, solvent evaporation has the advantages for its simpler, shorter assembling-time, and especially for highly ordered structure with large area obtained in the products.