The aim of the work described in this thesis is the development of highly porous materials (PolyHIPEs) which could find wide applications in separation science and in solid phase synthesis. Two systems were developed and studied. In the first one, PolyHIPE materials from divinylbenzene were synthesised in the presence of porogens of different chemical structures. These materials possess two levels of porosity: large pores ( 1 - 20 µm) which guarantee the flow of fluids under the application of small pressures and a fine porosity (1 - 100 nm) present in the walls of the foams which confer to the materials high surface areas (up to 700 m(^2)g(^-1)). The chemical nature of the porogens employed has a significant influence on the morphologies of the foams affecting both the dimension of the cavities and the fine porous structure. It was shown that the mechanisms operating at the emulsion stage and thus determining the characteristics of the final foams are the co-adsorption at the oil/water interface of the porogens and/or monomers together with the primary surfactant, and diffusion of the dispersed aqueous phase through the continuous organic phase. The latter phenomenon can be minimized by the appropriate choice of the surfactant system. The second system consisted of styrene/4-vinylbenzylchloride/divinylbenzene foams. The presences of a chloromethyl group render these PolyHIPE foams amenable to functionalization. Also in this case, the morphologies of the resulting foams were studied. It was shown that emulsion composition is the relevant variable affecting via the interfacial tension and viscosity not only foam morphologies but also their mechanical properties

No description available.

Graduation date: 1951

Thesis (PhD)--University of South Australia, 2004.

Systematic characterization of emulsion rheology has a substantial importance for its diverse industrial applications. However, it has not been achieved to date due to lack of a deformability controllable model emulsion. / Thesis (PhD)--University of South Australia, 2006

Atomic force microscopy (AFM) has been used to determine the interaction forces between a spherical silica probe and immobilised colloidal droplets of polydimethylsiloxane (PDMS) in aqueous solution. Between pH 4.5 and 9.5 where PDMS droplets and the silica probe are both negatively charged, a repulsive force is evident that increases less rapidly on surface approach than expected for electrical double layer interaction of rigid particles. The departure from hard-sphere behaviour, i.e. the deformation, has been determined and by varying the extent of internal cross-linking within the PDMS droplets, the influence of bulk rheology and interfacial properties on droplet deformation and nano-rheology has been isolated. For highly cross-linked droplets, the extent of deformation is controlled by the bulk rheology rather than the droplet's interfacial properties. Upon retraction of the surfaces, force curve hysteresis is observed and is due to the viscoelastic response of the PDMS. The extent of hysteresis is dependent on the rate of approach/retraction anf the loading force, and has been theretically fitted to obtain nano-rheological paraameters, which describe the droplet relaxation process. For liquid-like droplets, with a low level of cross-linking, no force curve hysteresis is observed and the elastic deformation may be described by a single spring constant. The spring constant is proportional to the surface tension (as controlled by surfactant adsortion) and the reciprocal of the droplet radius, i.e. deformation is controlled by the Laplace pressure. Furthermore, droplet deformation is altered by the presence of adsorbed nano-particles. These colloid probe AFM studies offer due insight into the deformation and interaction of emulsion droplets and have implications when considering the stability, adhesion and processing of emulsions. / Thesis (PhD)--University of South Australia, 2003.

Atomic force microscopy (AFM) has been used to determine the interaction forces between a spherical silica probe and immobilised colloidal droplets of polydimethylsiloxane (PDMS) in aqueous solution. Between pH 4.5 and 9.5 where PDMS droplets and the silica probe are both negatively charged, a repulsive force is evident that increases less rapidly on surface approach than expected for electrical double layer interaction of rigid particles. The departure from hard-sphere behaviour, i.e. the deformation, has been determined and by varying the extent of internal cross-linking within the PDMS droplets, the influence of bulk rheology and interfacial properties on droplet deformation and nano-rheology has been isolated. For highly cross-linked droplets, the extent of deformation is controlled by the bulk rheology rather than the droplet's interfacial properties. Upon retraction of the surfaces, force curve hysteresis is observed and is due to the viscoelastic response of the PDMS. The extent of hysteresis is dependent on the rate of approach/retraction anf the loading force, and has been theretically fitted to obtain nano-rheological paraameters, which describe the droplet relaxation process. For liquid-like droplets, with a low level of cross-linking, no force curve hysteresis is observed and the elastic deformation may be described by a single spring constant. The spring constant is proportional to the surface tension (as controlled by surfactant adsortion) and the reciprocal of the droplet radius, i.e. deformation is controlled by the Laplace pressure. Furthermore, droplet deformation is altered by the presence of adsorbed nano-particles. These colloid probe AFM studies offer due insight into the deformation and interaction of emulsion droplets and have implications when considering the stability, adhesion and processing of emulsions. / Thesis (PhD)--University of South Australia, 2003.

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xv, 188 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 172-182).

Thesis (M.S.)--Rochester Institute of Technology, 1992. / Typescript. Includes bibliographical references.