Synthesis and characterization of hybrid organic-inorganic silicate and siliconate materials

This dissertation is the culmination of two related research projects on the synthesis and characterization of hybrid organic-inorganic silicon-containing materials. Chapters 1-3 describes the preparation of hypervalent siliconate compounds and polymers. Alternatively, Chapter 4 focuses on the synthesis and evaluation of heteroatom-bridged polysilsesquioxane xerogels.; Chapter 1 discusses the preparation of "model" bis-siliconate compounds. Bis-siliconates represent molecular-level building blocks for the synthesis of ionomers containing the hypervalent siliconate functionality in the backbone of the polymer. Solution {dollar}sp1{dollar}H, {dollar}sp{lcub}13{rcub}{dollar}C, and {dollar}sp{lcub}29{rcub}{dollar}Si NMR spectroscopy, as well as Liquid Secondary Ion Mass Spectrometry (LSIMS), was used to verify the presence of the siliconate functionality. Chapter 2 presents the synthesis and characterization of the first representatives of synthetically prepared hypervalent polysiliconates. Alteration of reagents allows for the synthesis of linear pentacoordinate, network pentacoordinate, or network hexacoordinate polysiliconate materials. In addition, variation of the tetrafunctional condensing reagent affords polysiliconates exhibiting a wide range of physical properties. Polysiliconates are, in general, air-stable amorphous powders composed primarily of oligomeric linear and/or cyclic structures as indicated by NMR end-group analysis.; An interesting example of a macrocyclic tetrameric pentacoordinate oligosiliconate is presented in Chapter 3. A rigorous analysis was required to verify the structure of the compound. Analysis by solution NMR ({dollar}sp1{dollar}H, {dollar}sp{lcub}13{rcub}{dollar}C, and {dollar}sp{lcub}29{rcub}{dollar}Si), mass spectrometry, dilute solution viscosity, vapor pressure osmometry, and elemental analysis support a single diastereomeric structure.; Chapter 4 presents the synthesis and characterization of a family of heteroatom-containing alkylene- and arylene-bridged polysilsesquioxane xerogels. An in-depth discussion on the solid state NMR ({dollar}sp{lcub}13{rcub}{dollar}C and {dollar}sp{lcub}29{rcub}{dollar}Si), and surface area and pore size distribution analysis is given. Heteroatom incorporation into an alkylene- or arylene-bridging spacer dramatically altered the resulting bulk morphology of the xerogel. Specific surface areas for both the arylene- and alkylene-bridged xerogels were consistent, in general, with previously analyzed non-heteroatom containing xerogels. Pore volume distributions were extremely narrow and primarily confined to the low mesopore (alkylene-bridged) and micropore (arylene-bridged) size domains.