Date of Award
Doctor of Philosophy (PhD)
Chemical and Biomolecular Engineering
Kathleen J. Stebe
My research is in the field of interfacial phenomena. Since all materials are bounded by surfaces or interfaces, the ability to manipulate or tune interfacial properties is broadly important. I am interested in particle-laden fluid interfaces where surface tension plays a dominant role. In particular, I have investigated the effect of particle shape in the interaction and assembly of non-spherical microparticles at interfaces between immiscible fluids, such as the air-water or oil-water interfaces. In the first study, I showed experimentally that geometric features on the surface of the cylindrical microparticles, specifically the sharp edges, have a strong influence on both the capillary interactions and the micromechanics of the particle assembly. In the second study, I used creatively shaped particles to model the effect of surface roughness on the particle and carried out the first numerical and experimental demonstration of near-field capillary repulsion. Lastly, I demonstrated experimentally and analytically that on a curved interface with a gradient along one of the principal axes of curvature, both isotropic and anisotropic microparticles migrate to the region of high curvature. In addition, anisotropic microparticles conform to either an azimuthal or a radial orientation depending on their aspect ratios. My research provides fundamental knowledge for understanding, predicting and modulating the interactions between colloidal particles at fluid interfaces, with immense potential for various applications in which the interface stabilization is vital.
Yao, Lu, "Capillary Assembly of Anisotropic Particles" (2014). Publicly Accessible Penn Dissertations. 1509.