The Synthesis And Characterization Of Titanium Hybrid Silsesquioxane And Its Derivatives

The polyhedral oligosilsesquioxane (POSS) has an integral structure with high symmetry and has an average diameter of only 1.5 nm. POSS represents a rather versatile class of potential three-dimensional building blocks for the synthesis of nanostructured materials. In recent years, silsesquioxane-derived materials have received great attention due to their special structure and excellent physico-chemical, thermal and mechanical properties. In this dissertation, some kinds of silsesquioxane-derived materials have been synthesized.The metallasiloxanes have attracted considerable interest nowadays, because the presence of a metal in the siloxane framework often results in high thermal stability and improved catalytic and conducting properties. Titanium is often used as heteroatom due to its excellent photocatalytic activity. According to the literatures, incompletely condensed polyhedral silsesquioxanes is often used as precursor to synthesize titanium-hybrid silsesquioxanes.In this dissertation, a new king of titana-silica material was synthesized using cubic cage-like octasilicate as precursor. Then the material was modified by Methyl Red, Rhodamine-B and pyrocatechol separately. The modification expands the absorption ability of UV-Visible light of the material.In Chapter 2, cubic cage-like tetramethylammonium octasilicate was synthesized using ethyl silicate and tetramethylammonium hydroxide as precursors. And then Octa(dimethylsiloxy)silsesquioxane was synthesized by the reaction between octasilicate and chlorodimethylsilane. The products were characterized by FT-IR, TG-DTA and 29Si-NMR, which suggested that the cubic silicate cages were created in this way.In Chapter 3, a new kind of titanium hybrid silsesquioxane was synthesized using cubic cage-like tetramethylammonium octasilicate and dichlorodiethoxytitanium as precursors. The product was characterized byFT-IR, 29Si-NMR, UV-Vis, and XRD, which suggested that different from other titanium-silicon materials, the titanium hybrid silsesquioxane was formed with cubic cage-like POSS as building blocks and titanium as bridge atoms, and had a layer-structure.In Chapter 4, two kinds of dye-doped titanasilsesquioxanes were synthesized using titanium hybrid silsesquioxane, methyl red and rhodamine-B as precursors. The products were characterized by FT-IR and UV-Vis. A bathochromic shift was found after dye doping, and an explanation was given in this dissertation.In Chapter 5, a new kind of derivative of silsesquioxane was synthesized using titanium hybrid silsesquioxane and pyrocatechol as precursors. The product was characterized by FT-IR and UV-Vis. The product is stable and has a grand absorbance. A remarkable bathochromic shift was found after the reaction with pyrocatechol. This great change of the photochemistry property was explained with Molecular Orbital Theory in this dissertation.