A new design of dual-functional polyurea microcapsules was proposed for chronic wound dressings to provide both non-leaching infection control and sustained topical drug delivery functionalities. Quaternary ammonium functionalized polyurea microcapsules (MCQs) were synthesized under mild conditions through an interfacial crosslinking reaction between branched polyethylenimine (PEI) and 2,4-toluene diisocyanate (TDI) in a dimethylformamide/cyclohexane emulsion. An in-situ modification method was developed to endow non-leaching surface antimicrobial properties to MCQs via bonding antimicrobial surfactants to surface isocyanate residues on the polyurea shells. The resultant robust MCQs with both non-leaching antimicrobial properties and sustained drug releasing properties have potential applications in medical textiles, such as chronic wound dressings, for infection control and drug delivery.

In this study the unique Magotteaux Mill® system was used to control the grinding chemical conditions, which may be adjusted by varying grinding media, purging gas and pH, during grinding. An electrochemical apparatus was used to investigate oxidation-reduction behaviour of grinding media and sulphide mineral electrodes, as well as their galvanic interaction in-situ of the Magotteaux Mill®. Galvanic interaction between the grinding media (mild steel, 15% chromium, 21% chromium and 30% chromium media) and the sulphide minerals (bornite, arsenopyrite and pyrite) was initially quantified in-situ of the mill by electrochemical techniques under different grinding atmospheres (nitrogen, air and oxygen). An innovative mathematical theoretical model was developed to describe the effect of galvanic interaction on oxidation rates of the grinding media during grinding, which was verified by the experimental data. Galvanic interaction enhanced the oxidation of the grinding media and produced more oxidized iron species in the mill discharge. It was observed that oxidized iron species (EDTA extractable iron) was linear with galvanic current between the grinding media and the sulphide minerals, in agreement with the prediction of the theoretical model. The effect of grinding conditions on pulp chemistry, surface properties and floatability was investigated by the measurement of dissolved oxygen (DO), pH, pulp potential (Eh), ethylene diamine-tetra acetic acid (EDTA) extraction, X-ray photoelectron spectroscopy (XPS) and floatation recovery. / Thesis (PhDAppliedScience)--University of South Australia, 2005.

Thesis (PhDApSc)--University of South Australia, 2003.

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Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed March 26, 2009)