Synthesis of segmented silica rods by regulation of the growth temperature

The control of the diameter of colloidal structures is of fundamental interest and practical importance. We synthesized segmented silica rods by regulating the reaction temperature while the rods were growing. With higher growth temperatures, the segment diameter became smaller. Longer incubation times gave longer segments at the same temperature. Similarly, high temperature for the same incubation time gave longer segments. It appears that the correlation between temperature and diameter results from the relation between temperature and the size of the emulsion droplet, that is, the higher the temperature, the smaller the emulsion droplet. The control of the local diameter of segmented silica rods was possible by regulating the reaction temperature during growth. Segmented silica rods with controlled local thickness (such as thick-thin-thick, thin-thick-thin, or thin-thick-thicker) were thus obtained.