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Aqueous polyuethane (PU) colloids, like many other water-borne polymer colloids, have become an increasingly important class of materials in the surface coating industry. Three processing stages, the pre-dispersion, dispersion and postdispersion stages, are generally involved in the production of aqueous PU colloids. However, existing researches have neglected the importance of the dispersion stage. The present study aims to develop better understanding of the dispersion stage during the production of aqueous PU colloids. Non chain-extendable PU pre-polymer (PUp) is used to enable independent study of the dispersion stage and the phase inversion process is chosen due to its widespread industrial usage. Valid drop size characterisation techniques and phase inversion detection methods have been developed in this project. Three different dispersion regions have also been identified by changing the ionic group content of PUp. Each dispersion region is associated with a particular dispersion type. Those are (I) Stable aqueous emulsions that contain small PUp-in-water drops. They were produced using PUp with more than 0.2 mmole/g of ionic groups. (2) Aqueous PUp colloids with 0.05 ~ 0.2 mmole/g of ionic groups. These emulsions contain a mixture of drop structures, including simple drops and different multiple drops. (3) Aqueous PUp dispersions containing less than 0.05 mmole/g of ionic groups. These dispersions are not stable and the resultant dispersions separated when agitation was stopped. Modified phase inversion maps are introduced to represent the occurrence of all three dispersion regions. The modified phase inversion maps are partly analogous to those of conventional non-ionic-surfactant-water (nSOW) systems. The three dispersion regions have also been "reproduced" successfully using external surfactants as substitutes for the internal stabilising groups. A new catastrophic phase inversion mechanism is proposed to explain the existence of all three dispersion regions. Other variables studied during this project include different neutralising agents. different amount of carboxylic acid groups, operating temperatures and material addition rates. In conclusion, this project shows that the phase inversion process is a feasible route for producing aqueous polymer dispersions with little or no added external surfactants. Stable PUp-W dispersions can also be produced below the minimum ionic group content reported in existing literatures.

Controlling the assembly of amphiphilic molecules and micron-sized, disk-shaped particles at different length scales into ordered structures enables bottom-up organization which is of great interest to emerging technologies based on structured materials. The primary object of this work is the investigation of structure forming components - Zirconium phosphate (ZrP) discotic particles and polymersomes/ amphiphiles on their self-assembly and interactions. The effect of bilayer architecture of polymersomes on surface reactivity was investigated via fluorescent probing method. Established through complementary experiments, correlation between reactivity and molecule diffusivity in polymer-rich environment revealed the mechanism of reduced reactivity when tethered reactive groups are located deeper within the hydrophilic polymer layer. The phase diagram of charged nanoplatelets was constructed as a function of particle concentration, surface cation moiety, and ionic strength. Influence of surface cation on the isotropic-nematic transition was done by measuring the transition boundaries of discotic suspensions prepared by acid-base exfoliation reaction with a series of exfoliating agents. Furthermore, a novel phase transition was found, where platelet-platelet interaction was influenced synergistically by ionic strength and ion exchange. At low pH, directional inter-platelet attractions lead to the formation of low volume fraction colloidal gels. Alternative surface modification approaches, including biomolecule deposition and alkyl chain grafting were explored. Finally, self-assembly of platelets in emulsions and oil-water interface was examined. Surface modification was applied to link surface properties to stable emulsion-forming ability in mixed surfactant-particle system. Emulsion uniformity was achieved by microfluidic flow focusing method. Surface engineering and interaction control was demonstrated throughout this work to be viable approaches to the fundamental understanding of collective behaviors of individual building blocks.

The surface force apparatus (SFA) has been an important technique for making direct force measurements and has contributed enormously to our understanding of colloidal interactions. The conventional SFA has been limited to measuring forces between solid surfaces, until recently when a modified SFA was developed at the Ian Wark Research Institute [1]. A fluid drop (mercury) is introduced into the apparatus which allows a range of deformable surfaces to be studied in the SFA. This project is an extension of this technique. Interactions between a mica sheet and a mercury drop are studied, including the modification of mercury with self-assembled monolayers (SAMs) of thiol surfactants, and the drop deformation due to non-equilibrium adsorption effects and hydrodynamic forces. / SAMs can form spontaneously onto a surface by immersing the substrate into an appropriate surfactant solution. They have been used, generally formed on gold surfaces, for biosensors, chemical sensors, micro-electronics and detection of DNA and protein adsorption. In our study, mercury was chosen as the substrate, for its defect-free, renewable and molecularly smooth surface. The additional advantage of being an ideal polarisable electrode allows a potential to be applied to the mercury, and hence control of the surface forces. The charging behaviour of the mercury is changed by introducing a SAM onto the surface. An uncharged SAM (11-mercapto-1-undecanol or 11-mercaptoundecane) modifies the dipole potential of the mercury by replacing the water molecules oriented on the surface, whereas a charge SAM (11-mecapto-1-undecanoic acid) brings additional charges to the surface. / Drop deformation is an important factor when deformable surfaces are involved in colloidal systems, e.g. emulsions, foams, in mineral flotation and in biological systems. Drop profiles of a mercury surface which is already close ( ̃50 nm) to a flat mica sheet, with or without a SAM, were measured using the SFA technique. For the SAM-modified mercury, the negatively charged functional group (-COO⁻) yields a repulsion against mica, and a thin film is formed between the surfaces. When the applied potential was scanned negatively, desorption of thiols occurred at certain potentials, increasing the local solute concentration in the solution. The restricted flow of the solute within the small gap creates an excess osmotic pressure in the thin film compared to the bulk solution. As a result, the film pressure exceeds the internal pressure of the drop, inverting the drop curvature and forming a dimple. We propose that the drainage of the dimple is a diffusion-controlled process, which is supported by the comparison of the data with a simple model calculation. / For the bare mercury drop, a negative potential was applied to the mercury to provide a repulsion to form a thin film. Mica was then driven towards the mercury with an abrupt step. Beyond certain step sizes, a rippled shape - which we dub a “wimple” - was observed before it evolved into a classical hydrodynamic dimple. At small step sizes, no wimple was observed, but curiously the film in the central part thickens before eventually thinning out. This shows that fluid first flows towards the central axis before reversing its flow direction and flowing radially outwards. / Thesis ([PhDApSc(MineralsandMaterials)])--University of South Australia, 2005.

Errata pasted on front end cover. / Bibliography: leaves 194-210. / xi, 210 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this study is to investigate the conductivity of pHEMA gel electrolytes and improve the understanding of the absorbed water in such hydrogels. The effect of the variation of the water content on conductivity is investigated in two ways ; the introduction of OED cross linkers yields hydrogels of reduced EWC through alteration of the nature of the polymer network and progressive dehydration enables a study of the conductivity with decreasing water content for individual copolymers. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1996

Thesis (Ph. D.)--University of Chicago, 1921. / "Private edition, distributed by the University of Chicago libraries, Chicago, Illinois." "Reprinted from the Journal of biological chemistry, vol. XLV, no. 2, 1921; vol. LIV, no. I, 1922; the American journal of physiology, vol. LVI, no. I, 1921." Bibliography: p. 181, 18. Also available on the Internet.

Thesis (M.Eng.). / Written for the Dept. of Chemical Engineering. Title from title page of PDF (viewed 2008/04/12). Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.