武藤 浩行

The third series of images is from the work of Muto, Amano, Tan, Yokoi, Kawamura and Matsuda entitled “Ordered arrays of electrostatically assembled SiO2–SiO2 composite particles by electrophoresis-induced stimulation” (JSST, (2022); https://doi.org/10.1007/s10971-022-05854-5). This paper explores the formation of electrostatically-assembled SiO2-SiO2 composite particles from ensembles of monodisperse 200 nm and 16 µm particles. Composite particles consisting of a 16 µm SiO2 core decorated with the 200 nm SiO2 particles (left image) were initially assembled using polyelectrolyte adsorption to control the surface charge of the core and decorating particles. The assembly of these exquisite composites was subsequently achieved by applying controlled AC and DC electric fields to yield 2D hexagonal close-packed structures (right image) or an AC field coupled with gravitational sedimentation to generate ordered 3D hexagonal close-packed arrays.