Rapid Fabrication of Large-Area SiO<sub>2</sub> Nanoparticle Monolayer Films Via Water-Induced Interfacial Assembly

Abstract

Water/toluene interfacial self-assembly of nanostructures is a powerful bottom-up approach for film fabrication because of the low cost and high efficiency, and it is a simple and universal method for almost all low-dimensional nanostructures. The method involved adding alcohol and then toluene (here the dispersant was itself alcohol, only toluene was added) into SiO2 nanoparticle dispersion, and then a large quantity of distilled water was rapidly poured into the mixed system. Simultaneously, nanoparticles in the dispersion were extracted to the water/toluene interface, forming a thin film with a nearly perfect hexagonal close packed phase. Large-area nanoparticle monolayer films (e.g., more than 20 cm2) could be prepared in less than 1 min. The close-packed structures of these thin films were verified by a field emission scanning electron microscopy (FESEM, Hitachi S-4800, Japan). We also investigated the whole process of forming the films and found out the mechanism of water-induced interfacial assembly. As for the specific kinetic mechanism of the fabrication process, it is expected to further study in later time.