Size Control and Monodispersity of Silica Nanospheres and Applications in Nanofiltration

Due to their low reactivity and high thermostability, amorphous silicon dioxide nanoparticles have drawn much attention in the field of nanotechnology. This work reports on the synthesis methods and reaction parameters used to produce monodispersed silica nanospheres of systematically varied sizes using modified Stöber methods. Employing W/O microemulsion systems assisted by amino acid monomers and more traditional Stöber systems, nanosphere diameters were well controlled from single-digit nanometers to several micrometers. Effects of chemical compositions and other reaction parameters effecting TEOS hydrolysis were optimized for each Stöber system. Additionally, the monodispersed spheres were assembled into close-packed systems where the porosity and volumetric flowrates were controlled by the nanoparticle radii. Detailed characterization of the particles and arrays was performed using atomic force microscopy and scanning electron microscopy. Developing a porous system with a tunable effective pore size is a fundamental interest in the field of filtration.