Catherine P. Whitby

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We produce direct and inverse emulsions stabilized by solid mineral particles. If the total amount of particles is initially insufficient to fully cover the oil-water interfaces, the emulsion droplets coalesce such that the total interfacial area between oil and water is progressively reduced. Since it is likely that the particles are irreversibly adsorbed,(More)
We have investigated the rheology of concentrated oil-in-water emulsions stabilised by silanised silica nanoparticles. The emulsions behave like highly elastic solids in response to small, uniform strains. They become unstable and begin to break down, however, on yielding. We show that the emulsion elasticity is correlated with the salt concentration in the(More)
A study of the emulsification of silicone oil and water in the presence of partially hydrophobic, monodisperse silica nanoparticles is described. Emulsification involves the fragmentation of bulk liquids and the resulting large drops and the coalescence of some of those drops. The influence of particle concentration, oil/water ratio, and emulsification time(More)
The remarkable stability of nanoparticles attached to oil-water interfaces in macroemulsions hinders controlled detachment of these particles from emulsions. In this work it is shown that adding surfactant molecules which preferentially adsorb at the oil-water interface displaces nanoparticles from the interface. Surfactant adsorption at the oil-water(More)
We have investigated the potential of utilizing naturally occurring spore particles of Lycopodium clavatum as sole emulsifiers of oil and water mixtures. The preferred emulsions, prepared from either oil-borne or aqueous-borne dispersions of the monodispersed particles of diameter 30 microm, are oil-in-water. The particles act as efficient stabilizers for(More)
Droplet evolution in unstable, dilute oil-in-water Pickering emulsions was characterised using a combination of light scattering, confocal microscopy and rheology. Emulsions were formed at concentrations of silanised fumed silica particles that are not sufficient to prevent destabilisation. The key result is that destabilisation initially occurs via a(More)
The rate and extent of lipolysis, the breakdown of fat into molecules that can be absorbed into the bloodstream, depend on the interfacial composition and structure of lipid (fat) particles. A novel method for controlling the interfacial properties is to load the lipid into porous colloidal particles. We report on the role of pore nanostructure and surface(More)
We have studied the stability and structure of emulsions formed in the presence of colloidal mixtures of partially hydrophobic titania particles and hydrophilic silica particles. On their own, the titania particles attached strongly to the oil-water interface and stabilised emulsions, while the silica particles did not attach to the interface. Adding silica(More)
A study of the rheological behavior of water-in-oil emulsions stabilized by hydrophobic bentonite particles is described. Concentrated emulsions were prepared and diluted at constant particle concentration to investigate the effect of drop volume fraction on the viscosity and viscoelastic response of the emulsions. The influence of the structure of the(More)
This work reports on coalescence in oil-in-water Pickering emulsions subjected to simple shear flow. The emulsions were stabilized by silanized fumed silica particles forming layers a few hundred nanometers thick around drops that are tens of micrometers in size. The drop size and particle concentration in the emulsions were fixed, while the salt(More)