Investigation of the efficiencies of stabilizers for nanoparticles by synthetic boundary crystallization ultracentrifugation

A recently established synthetic boundary crystallization ultracentrifugation method was applied to stabilized inorganic nanoparticles. As a model system stabilized CdS showing the quantum size effect was chosen allowing both independent access to particle size via UV-vis absorption measurements and the elaboration of the influence of different stabilizer molecules on the CdS particle size distributions. The results were also compared to those derived from light scattering. It was found that the analytical ultracentrifugation method is sensitive to very small changes in the particle size distributions in the angstrom range, yields particle sizes down to the size range of a critical crystal nucleus and allows the calculation of the thickness of the stabilizer shell if the overall diameter is known from light scattering. Thus, synthetic boundary crystallization ultracentrifugation is suitable to study the general influence of additives on crystallization processes.