A combination of surface analytical techniques, colloid probe Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) was used to optimise the grafting density of covalently attached 5, 20 and 40 kDa methoxy-terminated PEO layers (under marginal solvation (cloud point) conditions for the PEO molecules). The combination of these techniques allowed us to relate the PEO layer density and molecular conformations to the range, magnitude and types of forces generated by coatings of various grafting densities. The key optimisation parameter was the grafting time with the concentration of PEO in solution having a weaker effect. Oxidation of the substrate occurred, but did not significantly limit the surface density of the functional groups used to chemically attach the PEO molecules. Interactions between the substrate and silica were electrostatic in origin and did not contribute to the interaction between silica and the PEO surfaces due to salt screening effects Surfaces with dense, highly stretched PEO layers (brushes) generated purely repulsive forces at all separation distances, arising from compression by the silica spherical probe used. The force profiles for lower density surfaces comprised long-ranged attractive and short-ranged repulsive forces. The attractive forces were most likely due to attractive bridging interactions between the PEO chains and the SiO2 surface. For low grafting densities, i.e. inter-chain grafting distances, s &gt ??RF, the PEO layers were not strongly stretched and free to adsorb onto the opposing silica surface. XPS analysis demonstrated that HSA and Fibrinogen adsorbed onto low density 20 kDa PEO coatings (s &gt ??RF), most likely via diffusion through the PEO layer. No protein adsorption was found (detection limit &gt 10 ng/cm2) on high density, ???strongly stretched brush??? coatings (s &lt ?? RF). Analysis of data from the more sensitive Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) techniques indicated that low amounts of adsorbed HSA, lactoferrin, lysozyme, and IgG were present on high density 20 and 40 kDa surfaces; the most likely explanation being attractive interactions between the proteins and the PEO layers during the protein adsorption experiments. ToF-SIMS data obtained for the strongly stretched (s &lt ?? RF) 5 kDa PEO surfaces suggested that no protein was adsorbed, in line with the XPS data for the same surfaces.

The chemistry during regrinding is critical to flotation. It has significant effects on mineral surface properties and can lead to different mineral floatabilities. This research seeks to quantify contributing factors to changes in mineral flotation behavior with grinding and regrinding. The influence of the particle breakage mechanism on mineral floatability is also investigated. In this research, sulphide mineral surface species and hydrophobicity were analyzed by a range of techniques, including X-ray photoelectron spectroscopy (XPS), surface area measurement (BET), ethylene diamine-tetra acid (EDTA) extraction and contact angle measurements. / Thesis (PhD)--University of South Australia, 2010

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

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 (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 143-150). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references (leaves 179-187). Also available via World Wide Web.

Thesis (M.Sc.) - Carleton University, 2008. / Includes bibliographical references (p. 92-97). Also available in electronic format on the Internet.

Thesis (M.Sc.) - Carleton University, 2008. / Includes bibliographical references (p. 76). Also available in electronic format on the Internet.

Thesis (Ph.D.)--University of Melbourne, Dept. of Chemical and Biomolecular Engineering, 2009. / Typescript. Includes bibliographical references (p. 129-141)