Preparation of ordered mono-particulate film from colloidal solutions on the surface of water and continuous transcription of film to substrate

By spreading an alcohol suspension of hydrophobic mono-disperse silica particles on the surface of water, an ordered mono-particulate film might be self-assembled on it. In this investigation, the formation mechanism of an ordered mono-particulate film on the water's surface was elucidated. During the initial stage of the suspension spreading, the floating hydrophobic particles that appeared on the surface of water formed many small particle film fragments. These fragmented films fastly move through the water's surface by two-dimensional Marangoni convection. As the particle film coverage of the water's surface increased, the two-dimensional motion of the fragmented films on the surface of water gradually became weak. These aggregated and then formed a large two-dimensional particle film. The particle film was compressed by the two-dimensional pressure induced by the Marangoni convection. This compression would drive the two-dimensional ordering. The formation of ordered two-dimensional particle arrays on the surface of water would be a kind of Kirkwood-Alder phase transition phenomenon. The prepared particle films are easily transferred to a substrate by withdrawing the immersed substrate. The SEM observations of the transferred particulate films reveal that the particle film formed on the surface of water was transferred to the substrate without any significant deterioration of the ordering regularity. Furthermore, it can be concluded that both the optimum hydrohobicity of the particles and Marangoni surface convection are required to form a highly ordered arrangement of the particles. Especially, the Marangoni convection plays an important role in the particle ordering process. The continuous fabrication of the particulate film on a substrate will become possible by transcribing it on the substrate at the same time while forming the particle film on the surface of water.