| Colloidal particles can stabilize a fluid interface. This phenomenon, first observed over a century ago, enables a robust "bottom-up" approach for synthesis of functional materials with well-defined microstructure using colloids with tunable chemistry and geometry as building blocks. Familiar examples are particle-stabilized emulsions and foams, which are utilized in several industries including personal products, foods, and pharmaceuticals. In this dissertation, the assembly of particles at fluid interfaces is investigated with two underlying intentions: to develop novel methods for synthesis of microstructured materials, and to provide new insight into how the 3-D morphology of particle-stabilized interfaces can influence the rheological properties of soft materials. For materials synthesis, colloidal particles with specific wetting properties arrest spinodal decomposition of a partially miscible fluid pair. The resultant non-equilibrium microstructure, known as a bijel , is then used as a general platform to synthesize a novel family of bicontinuous macroporous, hierarchically porous, and composite materials with tunable chemistry and morphology. Applications for these materials are numerous and include catalysis, energy systems, separations, and tissue engineering. For rheometry studies, confocal microscopy and conventional rheometry are used to elucidate links between the microstructure and mechanical properties of a unique class of solid-stabilized emulsion formed by the bridging of fluid droplets by an interfacial particle monolayer. Remarkably, the rheological behavior is governed predominately by the solids loading and can be tailored irrespective of the droplet volume fraction. The identification of this rheological hallmark could provide a means toward the improved design of modern products that utilize solid-stabilized interfaces. |
