Synthesis and structure of silica-based nanostructured materials

Nanostructural materials are of great interest to the development of a wide range of technologies from microelectronic insulating layers to elastomer reinforcement. This dissertation focuses on the production of inorganic oxides nanopowders and monolithic low density solids. There are two major routes to nanostructured synthesis for inorganic oxides such as silica and titania: solution synthesis and flame synthesis. For silica, there are commercially realized in precipitated silica, for example, Hi-Sil, and fumed silica, Aerosil, respectively.; The third to fifth chapters of this dissertation discuss a new synthetic route to powders which takes advantage of both aerosol and solution routes; the aerosol-gel powders. Chapters 6 to 8 deal with a separate process of incorporation of organic component for solution routes processes for the production of monolithic xerogels for insulation. Chapter 9 discusses flame synthesis in the context of a structural analysis. The structure of inorganic oxides is complex consisting of multiple levels of structure at different size scales. For example, flame synthesized silica contains nano-scale primary particles which yield high surface area, a mass-fractal aggregate structure on the nano-scale to colloidal scale (which allows access to nano-scale) and agglomerates of aggregates on the colloidal to micron-scale.; Microscopy is useful in examining narrow regions of these in orders of structural size but, in order to describe the interrelationship between levels of structure and to use a fractal description of these structures, researchers often resort to small-angle scattering of x-ray and light. A large portion of this dissertation deals with the use of small angle scattering to describe mass-fractal growth processes aimed at tunable nanostructure. Additionally, gas adsorption techniques are critical for the determination of surface areas in these materials.