Colloids like quantum confined semiconductor nanoparticles in the size range of only a few nm are promising materials due to their outstanding electro-optical properties. However, for optimum product dispersity, a post-synthetic narrowing of a particles size distribution often is necessary. This can be realized by size selective precipitation (SSP) where the preferential flocculation of larger particles is induced by addition of a poor solvent. The method is applicable to various colloids, like CdS(e), PbS(e) ZnS(e) or gold and enables a highly efficient classification of particles between 1 nm and 5 nm in diameter.1-3
However, the complex interplay between van der Waals interaction and the chemical interaction between the ligand bound to the particle surface and the solvent mixture is still not sufficiently understood. In this contribution a detailed mechanistic study on SSP is presented. It proves that SSP is a highly efficient and robust process that can be applied within a continuous synthesis setup. Moreover, our study allows a theoretical description of the classification based on the separation efficiencies. In conclusion, our work reveals that the in-depth understanding of colloidal interactions is a key-step towards an optimized and knowledge-based process design.
Literature:
1. Murray, C. B.; Norris, D. J.; Bawendi, M. G., J. Am. Chem. Soc. 1993, 115, 8706-8715.
2. Saunders, S. R.; Eden, M. R.; Roberts, C. B., J. Phys. Chem. C 2011, 115, 4603-4610.
3. Segets, D.; Komada, S.; Butz, B.; Spiecker, E.; Mori, Y.; Peukert, W., J. Nanopart. Res. 2013, 15, 1486.
doris.segets@fau.de
