Spherical colloids with isotropic properties have been used as building blocks to assemble a variety of 2D and 3D structures in past, such as FCC, HCP, and BCT crystals. We recently, however, have observed new type of sphere-packing under the influence of electric field at the liquid-solid interface. At low concentration and low frequency of the electric field, the isotropic spheres can form a series of colloidal clusters. The plot of cluster distribution shows non-trivial peaks for trimer, tetramer, hexamer, and nanomer. At high concentration, the colloidal clusters will further assemble and connect themselves into a good variety of two-dimensional non-close-packed networks. By precisely controlling the electric field strength, frequency, volume fraction of colloids, and ionic strength, we have made diversified non-close-packed structures that have potential applications in photonic crystal, catalysis, or filtration. 

Novel non-close-packed structures assembled by spherical colloids under electric field

243rd National Meeting (2012)

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