In this thesis, I study the self-diffusion of colloidal particles at soft (liquid/liquid) interfaces using optical microscopy and particle tracking methods. Several colloidal model systems with different interaction potentials are used, including Polymethylmethacrylate (PMMA with PHSA stabilized layer) spheres at the decalin-water interface, silica spheres (weakly charged) at the water-air interface and polystyrene latex spheres (highly charged) at the water-air interface. These systems differ not only in the equilibrium structures but also in the short-time and long-time self-diffusion. I study the effect of hydrodynamic interactions on the short-time self-diffusion for the hard-sphere-like PMMA and silica particles. Meanwhile the long-time self-diffusion of highly charged polystyrene...[ Read more ]

In this thesis, I study the self-diffusion of colloidal particles at soft (liquid/liquid) interfaces using optical microscopy and particle tracking methods. Several colloidal model systems with different interaction potentials are used, including Polymethylmethacrylate (PMMA with PHSA stabilized layer) spheres at the decalin-water interface, silica spheres (weakly charged) at the water-air interface and polystyrene latex spheres (highly charged) at the water-air interface. These systems differ not only in the equilibrium structures but also in the short-time and long-time self-diffusion. I study the effect of hydrodynamic interactions on the short-time self-diffusion for the hard-sphere-like PMMA and silica particles. Meanwhile the long-time self-diffusion of highly charged polystyrene latex particles is investigated using the exponential entropy scaling law.