Phase behavior of colloidal silica rods

Recently, a novel colloidal hard-rod-like model system was developed which consists of silica rods [Kuijk et al., JACS, 2011, 133, 2346]. Here, we present a study of the phase behavior of these rods, for aspect ratios ranging from 3.7 to 8.0. By combining real-space confocal laser scanning microscopy with small angle X-ray scattering, a phase diagram depending on concentration and aspect ratio was constructed, which shows good qualitative agreement with the simulation results for the hard spherocylinder system. Besides the expected nematic and smectic liquid crystalline phases for the higher aspect ratios, we found a smectic-B phase at high densities for all systems. Additionally, real-space measurements on the single-particle level provided preliminary information on (liquid) crystal nucleation, defects and dynamics in the smectic phase.