Particle dynamics and microrheology at liquid-liquid interfaces
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Solid-stabilized emulsions, often refer to as Pickering Emulsions, have the ability to provide a simple and convenient experimental template to meet various requirements, such as changing property of solid particles, oil phase viscosity and interfacial curvature. The confocal laser scanning microscope (CLSM) is a useful and convenient tool to investigate the dynamics of particles at emulsions interfaces. Here we have employed Pickering emulsions as an experimental template and confocal laser scanning microscopy as a tool to study the dynamics of solid particles at liquid-liquid interfaces. In Chapter 4.1 and 4.2, the diffusion behavior of colloidal particles at oil-water interfaces is studied using Pickering emulsions as templates. The solid particles are sulfate modified polystyrene microparticles with diameters of 1.1 10-6 m and the oil phase is polydimethylsiloxane oil (PDMS) or octamethyltrisiloxane with different viscosities. The confocal laser scanning microscopy is used as a tool to observe the dynamics of microparticles at emulsions interfaces. The main discussion focuses on the effects of interfacial curvature, cluster size, and oil phase viscosity on the diffusive behavior of solid particles at oil-water interfaces. In Chapter 4.3 and 4.4, both of one-particle microrheology and two-particle microrheology are used to investigate the microrheologiccal data at the poly (dimethylsiloxane) oil-water interfaces. The dynamics of charged microparticles are observed using confocal laser scanning microscopy (CLSM) at the liquid-liquid interfaces. The experimental template is Pickering emulsions. For one-particle microrheology, the different charged sub-microparticles are used as tracers and mobility of the sub-microparticles depend largely on the viscoelastic properties of the oil phase and the wettability of the solid particles. However, those phenomena can be ignored in two-particle microrheology. In addition, the potential of microrheology at liquid-liquid interfaces is also developed in both two methodologies. The apparent loss modulus, storage modulus, and relaxation time of the oil-water interfaces are gathered at the liquid-liquid interfaces. Finally, the difference between the results of one- and two-particle microrheology is compared.