<>Colloidal Crystals of Polystyrene with High Surface Charge in Dilute Aqueous Suspension

Colloidal crystals with high quality mentioned in numerous literatures were obtained mostly under the condition of high concentration suspension of colloidal spheres, our group has acquired polystyrene colloidal crystals with high concentration of colloidal particle, PS diameters range from 120nm to 250nm, the concentration of suspensions are about 6~10wt%. While colloidal crystal with low suspension concentration has been wined, lower than 2wt%, which irradiated flowery colors under sunshine in the proceeding of crystalline, once the colloidal crystal arrange into single crystalline, the irradiated light will be single color in one direction. The reason that dilute concentration suspension can form colloidal crystal is that the PS colloidal particles had high surface charge density, so the particle had strong repelling interaction each another affording the longer range crystal lattice.