Preparation of 3-dimensional SiO2 structures via a templating method

Three-dimensional (3D) SiO₂ has been prepared by coating silica on the surface of a template polymer and a sequent calcination of the silica/polymer composite. The template polymer that has 3D skeletal structure was prepared by curing epoxy resin in polyethylene glycol mediums using diethylenetriamine as a curing agent. The coating of silica on the polymer surface was accomplished through a slow in situ hydrolysis of infiltrated ethyl silicate in the interconnected pore network of the template polymer. The thickness of silica layer was controlled in a range of 20-80 nm by changing the total amount of ethyl silicate in hydrolysis. The 3D structures of silica were characterized by scanning electronic microscopy, transmitting electronic microscopy, Fourier transform infrared spectroscopy and surface area measurement. The light scattering of the 3D silica filled with liquid medium can be minimized by tuning the refractive index of the liquid medium to be the same as that of amorphous silica in the 3D structure.