Single- and multi-layered patterns of polystyrene and silica particles assembled with a simple dip-coating

A simple dip-coating method was examined to fabricate two-dimensional particle arrays on glass substrate with the use of submicron-sized, highly monodisperse particles of silica and polystyrene (PSt). This method was demonstrated to be applicable to the fabrication of particle monolayer with high regularity. The monolayer of PSt particles arranged with the dip-coating could be separated from the substrate by immersing it into water, leading to formation of a mono-layered film of the PSt particles. Repetition of the dip-coating was also applicable to multi-layering with silica and PSt particles. A dip-coating with 520 nm PSt particles accompanied by a dip-coating with 233 nm silica particles formed Kagome lattice composed of the silica particles under the monolayer of hexagonally arranged PSt particles. The lattice formation indicated that the silica particles crept under the monolayer of PSt particle in the second coating with the silica particle suspension. Double dip-coatings with different silica particle sizes in the second coating were performed to examine the effect of particle size on creeping under the monolayer. Silica particles much smaller than the PSt particles were gathered in a void between the substrate and the monolayer of PSt particles hexagonally arranged. A high concentration of the small silica particles in the second dip-coating could form hemi-sphere-typed inverse opal with little defects of silica particles after heat treatment at 600 °C.