In order to clarify the role that water plays in the photocatalytic process, changes in the IR and Raman spectra of P25 TiO₂ thin films were observed upon exposure to liquid water. Further investigation of these spectral changes via dehydration of thin films under nitrogen and oxygen of different humidities led to the observation of spectroscopic features that have been assigned to localised surface phonon modes. When the effect of UV irradiation on these features was investigated, a broad IR absorption due to transitions of electrons in shallow traps was detected under dry nitrogen but not under dry oxygen. Further investigation of the photocatalytic properties of P25 TiO₂ showed a complete removal of a stearic acid film. The final products have been tentatively assigned to a mixture of short chain carbonyl species and adsorbed carbonates as well as carbon dioxide and water. The IR spectrum of the fuel cell membrane material Nafion is complex and literature data varies in some of the assignments. The compound perfluoro(2-ethoxyethane)sulfonic acid was used as a model compound for the Nafion side chain resulting in a clearer assignment of the Nafion IR spectrum. In light of these new assignments changes induced in the region 1100-1300 cm⁻� by variation in humidity and ion exchange have been shown to be mainly the result of changes in the sulfonate asymmetric stretching modes. By flowing a series of solutions containing tetramethylammonium ions and perchlorate ions the surface charge characteristics of a Pt black film were determined in the pH range 2-12. There proved to be a weak positive charge below pH 4 and a weak negative charge above pH 9. Between these points there appeared to be no overall charge on the surface. When perfluoro(2-ethoxyethane)sulfonic acid was adsorbed to a Pt black film changes in its IR spectrum indicated a strong binding via interactions between the sulfonate groups and the Pt surface. The nature of the adsorption of Nafion was less clear cut and, whilst adsorption is strong, it seems possible that hydrophobic interactions between the Nafion backbone and the surface are involved.

Conventional techniques for contact angle measurements do not perform well for small particles. The equilibrium capillary pressure technique (ECP) consists in measuring the pressure required to prevent liquid penetration into a packed bed of particles and calculating the contact angle from a simple model, namely the equilavent capillary model. The ECP is well suited for the measurement of advancing contact angles. In its most convenient version the capillary pressure is measured for two different liquids (one of which is fully wetting and thus allows the calculation of the effective capillary radius). The use ECP to obtain the receding contact angle on powders has been developed. The major difference bertween a liquid penetrating a porous bed and retreating from it is that liquid pockets are left behind in the receding case. Effectively, this reduces the porosity of the packed bed. The volume fraction of the retained liquid apparently depends on the surface tension of the liquid but is only marginally affected by the wettability and size fraction of the particles. Therefore a simple procedure for the determination of the receding contact angle, based on the use of a calibrating liquid, is outlined and verified. The approach gives realistic values for the receding contact angle. / Thesis (PhDApSc(MineralsandMaterials))--University of South Australia, 2005.

In this study a variety of surface modifiers were absorbed onto titania pigment and their interaction examined. / Thesis (PhDAppliedScience)--University of South Australia, 2006.

The wettability of titania is an important factor in numerous industrial and natural processes. It is, as for most oxide surfaces, mainly determined by the density of hydroxyl groups (titanols). / The influence of external stimuli - heat and UV light - on the surface of titania was investigated with a number of surface-sensitive techniques: secondary ion mass spectroscopy, atomic force microscopy, streaming potential and contact angle measurements. Measurements were done in parallel on silica. / Thesis (PhDApSc(MineralsandMaterials))--University of South Australia, 2005.

The thesis presents a technique for and results of surface force measurements in a 3-phase system. The phases are a solid medium (mica), fluid (water and water-based electrolyte solutions) and gas (an air bubble). Analysis of deformation of the air bubble with respect to mutual position of the bubble and the mica surface, the capillary pressure of the undeformed bubble surface, the capillary pressure, and the disjoining pressure provide data for calculation of the air-liquid surface electrical potential. Furthermore, the information extracted from the deformation analysis made it possible to draw a conclusion regarding the nature of electrical double-layer forces in the system and, to some degree, about the effect of ion properties on the surface charging properties of the air-liquid interface. / Surface forces between an air bubble and a flat mica surface immersed in aqueous electrolyte solutions have been investigated using a modified surface force apparatus. This method allows forces to be detected in two regimes: at long range where the bubble is distorted slightly by the surface forces, and at short range where the force is manifest as disjoining pressure in a thin wetting film separating the bubble from the solid. The force was calculated from the equilibrium (or quasi-equilibrium) shape of the bubble surface. The experiments clearly show that long-range double-layer repulsion acts between mica and an air bubble in water and electrolyte solutions of different concentration. Double-layer repulsion indicates that the air bubble surface is negatively charged. However, there is clear evidence that charge regulation occurs at the air-water interface to maintain a constant surface potential, and as a result of this, the charge at this interface changes from negative to positive as the bubble approaches the negatively charged mica surface. Because of the attraction that arises due to the charge reversal, excessive force is required to separate the bubble from the mica, though the mica remains completely wetted by the aqueous phase. / The air-liquid surface potential has been evaluated from fitting a theoretically calculated shape to experimental measurements of bubble shape and film thickness, where the theoretical bubble shape was obtained from the numerical solution of the augmented Young-Laplace equation. Potential on the air bubble surface mainly depends on the concentration of electrolyte but is insensitive to the type of cation or anion within the low range of concentration investigated here. / The more important issue for such concentrations appears to be the electrostatic interaction between ions in solution and the air bubble interface. Therefore at the concentrations investigated, the potential on the gas-liquid interface arises due to the non-specific adsorption of ions to oriented water dipoles at the interface. / Thesis ([PhDApSc(MineralsandMaterials)])--University of South Australia, 2005.

The aim of the research presented in this thesis was to increase the understanding of the interaction between polymeric dispersants and titania pigment particles. In particular, the effects of dispersants of varied functionalities on the pigment dispersion behaviour in both aqueous suspension and dry paint film were investigated. / Thesis (PhDEng(MineralsandMaterials))--University of South Australia, 2004.

Hydrophobic colloidal suspensions are common in nature and industry. DLVO theory has been used to model the interactions between colloidal particles for decades, however the origin of long-ranged attractive forces observed between hydrophobic colloids remains the subject of much debate. In an effort to understand these forces and improve the prediction of colloidal stability, the colloidal stability of synthetic silica and titania was studied at various concentrations of dissolved gas, KCl electrolyte and pH. / Thesis (PhD)--University of South Australia, 2003

Thesis (PhDApSc(MineralsandMaterials))--University of South Australia, 2001.

Thesis (PhD) -- University of South Australia, 1992

Thesis (PhD)--University of South Australia, 1999