Assembly of sub-micrometer spheres into 3D periodic structure

In this paper, monodisperse silica spheres with diameters ranging from 100～700nm are synthesized following the stober method. By using electrophoretic aided sedimentation, silica colloidal spheres with different diameters are self assembled into long range ordered 3D arrays. The SEM was employed for structure and morphology characterization. Three other assembly methods including gravitational sedimentation, centrifugation and filtration were compared with electrophoretic aided sedimentation.