NMH studies of porous silicate gels and related materials: both in the solid and solution-state

Abstract

The purpose of this thesis is to describe research, using both solid and solution-state NMR techniques, to investigate the properties of a wide variety of silicon-containing materials. One solid-state (^29)Si NMR technique ((^29)Si-(^1)H cross-polarisation), and the experimental aspects important when using it, has been discussed in detail, and later used together with single pulse (^29)Si NMR techniques, to obtain information concerning geometry and local site symmetry of silicon sites in organo silicon compounds and silicate minerals. These techniques, together with a range of h CRAMPS experiments have also proved to be powerful tools for investigating the structure and properties of porous silicate gels (i.e. xero gels). (^29)Si and (^23)Na NMR measurements have been used to acquire evidence for the relaxation mechanisms of silicate species present in aqueous alkaline silicate solutions, and a technique for investigating the properties of sodium ions in colloidal silica solutions is tentatively proposed. Conclusions are drawn from the results obtained, demonstrating that where structural information can be obtained from these systems using other techniques (e.g. X-ray diffraction) NMR proves to be a valuable adjunct. However, in situations where this information is unknown or difficult to obtain using other techniques, NMR may yield new insights into the structural properties of the materials.