Preparation of TiO2 coated monodispersed silica spheres

Monodispersed colloidal spheres, especially high refractive index colloidal spheres have potential applications for the preparation of 3-dimensional photonic crystals, especial in the present work, the preparation of silica-titania core-shell spheres were carried out by using different titania precursors, Ti(OPri)(4) and Ti(OBun)(4) to coat the monodispersed silica spheres with the size 400 nm. Transmitting and scanning electron microscopy (TEM and SEM) and EDS were used to investigate the size an shape of the coated spheres, an the contents of silicon and titanium in the coated spheres. The results showed that the sphere size reached ∼ 500 nm and no sticking existed between the spheres; upon using TPOT, the sphere size reached ∼ 600 nm but sticking existed between the spheres, upon using TBOP.