Confocal microscopy of hard sphere colloidal suspensions

This thesis investigates the formation and rheology of hard sphere crystals using confocal microscopy. Our experiments employ a colloidal system composed of poly(methyl methacrylate) (PMMA) particles stabilized by poly(hydroxystearic acid) (PHSA) which have been demonstrated to exhibit hard sphere behavior. These systems have been extensively studied using light scattering and bulk rheology, but the use of microscopy offers many important experimental advantages that allow controls and measurements that are unavailable or impractical with conventional techniques.; We introduce a method for controlling density in soft systems using applied external fields, useful for small volumes. A quantitative theory for this technique is developed to exactly predict concentrations in a given system. Measurements on density-matched hard sphere colloidal particles confirm this theory and allow us to produce large colloidal crystals.; A patterned template surface can be used to nucleate and grow oriented crystals. We use confocal microscopy to follow the three dimensional growth from the surface template. The growth can be understood in terms of the Wilson-Frenkel growth law and allows us to measure the kinetic prefactor in colloidal crystallization. The crystallization front is rough on the scale of the colloidal particles and the growth rate as a function of mean curvature can be used to measure the fluid-solid surface tension. The elastic response of the resulting crystal can be measured from cross-correlations of thermally driven particle fluctuations. From the radial and angular dependence of the response, the full elastic tensor can be measured.