Abstract
This thesis is concerned with the physical chemistry of alkoxide sol-gel processing of a novel silica-titania material. A detailed discussion of sol-gel theory precedes a theoretical discussion of SiO2-TiO2, methods of coating and spectroscopic methods which can be used on sol-gel systems. The application of microscopy, adsorption and thermal methods as well as their corresponding experimental conditions is also addressed. Pre-hydrolysis and reflux synthetic routes have been investigated in order to maximise the number and distribution of Si-O-Ti linkages, homogeneously throughout the bulk without phase separation, using Si(OEt)4 and Ti(OPri)4 precursors. The chemistry which brings about Si-O-Ti bond formation during the initial stages of the process, the kinetics and extent of hydrolysis and condensation have been addressed and consideration given to methods of improving the characterisation process. Sols and immature gels were characterised using 29Si NMR, UV-Vis and TEM prior to being spin coated at a given viscosity to yield two-dimensional thin films on fused silica substrates. Such films were further characterised by SEM, AFM, FT-IR, SIMS, contact angle and neutron reflectance and the effect of functionalising with perfluoroalkylsilane as a means of improving hydrophobicity was investigated. Mature bulk three-dimensional oxide gels have been characterised by FT-IR, FT-Raman, UV-Vis, ESR, CPMAS 29Si NMR and, TGA-DTA, TPR, XRD, XPS and S BET. The properties of the systems are discussed in the light of these results. The SiO2-TiO2 has also been investigated for its industrial potential. As thin films, it has been shown that they can be tailored to exhibit high reflection, anti-reflection and protection for the indoor lighting industry and can be further functionalised to impart surface hydrophobicity. The thesis concludes with details of papers, posters and presentations which have been given over the past three years and a consideration for further potential work.