Preparation of Inks with Monodisperse Colloidal Silica and their Self-Assembly in a Ink-Jet Printed Droplet

摘要

Semispherical self assemblies of colloids have been fabricated on a substrate using inkjet printing with an ink of submicron-sized monodisperse silica particles. Colloidal silica has been prepared by Stoeber process. The shape and monodispersity of the synthesized colloidal particles were observed by scanning electron microscopy (SEM) and laser light scattering particle analyzer. Simple test patterns on various substrates (silicon wafer, Cu foil, and Mylar film) were printed with commercial HP printer. It was found that the uniformity and spatial extent of the self-assembled colloidal silica within a dot were significantly influenced by the contact angle between ink and substrates. Ink droplets printed on the hydrophobic Mylar film maintain a higher contact angle as compared to the hydrophilic substrates such as Si wafer. Slower evaporation and high capillary stress exerted on the ink droplet allow hemispherical colloidal aggregates with an ordered internal structure on Mylar film.