Abstract
This thesis is concerned with the possibility of producing novel materials by the sol-gel method that could be incorporated into a new sensing system to be used for the detection of hydrocarbons, in particular methane. Possibilities for a new system include coating optical fibres, at pre-determined points, with a material that causes some sort of disruption in the signal of the fibre when in contact with a hydrocarbon or specifically methane. Dip coating an optical fibre with a sol-gel would be a method for producing an optical fibre based system. This would provide variable chemistry, refractive index and hydrocarbon sensitivity. New silica-based sol-gel materials are presented and titania is incorporated to some of these materials in order to improve the catalytic potential of the system and to increase the refractive index. In order to increase the hydrophobicity and elasticity of the final coatings, organic modifiers are added. The sol-gel materials are characterised by a variety of techniques as both monoliths and thin films. Along with the characterisation, the samples are analysed to determine their potential to adsorb methane and water and the possibility of incorporating the samples in to an optical fibre sensor system utilising ultra-violet / visible spectroscopy. The presence of titania and / or organic modifiers in a silica based sol-gel system are seen to increase significantly the extent of methane adsorption and decrease the extent of water sorption at 293 - 298 K. It appears that having both titania and organic modifier gives a bigger effect on adsorption than either one alone. The reasons for this are considered in detail.