A self-assembly approach to fabricate the patterned colloidal crystals with a tunable structure

Several different ordered patterns with silica microspheres, including one-dimensional (1-D) colloidal lines, gradient colloidal arrays and three-dimensional (3-D) colloidal crystals were prepared via adjusting the colloidal concentrations and the prepattern geometry on the substrate. The nucleation and crystallization process of microspheres was revealed. The colloidal patterns were found to grow up from the nucleation sites at the edges of the prepattern to the center of the prepattern channels by a combination of gravity driven sedimentation, evaporation-induced capillary forces (dominant), and a strong interaction including Van der Waals attraction between the prepattern walls and the microspheres.