Effect of electrolytes on the slow aggregation of TiO2 nanocrystals

We studied the slow aggregation of dilute TiO2 hydrosols containing narrow fractions of nanocrystals separated from polydisperse sol by the stepwise coagulation with portions of HCl. It is shown that the kinetics of this process and the structure of formed aggregates greatly depend on the ionic strength and the pH of a medium. It is suggested that, in the presence of various electrolytes, the aggregation proceeds by an identical mechanism. In this case, highly ordered aggregates are formed in which there are thin layers of medium between TiO2 nanocrystals.