Functional materials based on core-shell type nanoparticles
Final Report Abstract
Research within the project “Functional materials based on core-shell type nanoparticles” was focused on the “synthesis, characterization and functionalization of rodlike gold nanoparticles for photothermal applications”. Within the first two years of the project the primary objective of the research was to elucidate the role of auxiliary reagents in the established seeded-growth synthesis of gold nanorods and to identify conditions that facilitate the reduction of the amount of (cytotoxic) surfactants needed to induce anisotropic particle growth. Major progress that has been achieved comprises: First, the demonstration of surface-reconstruction processes on high-energy crystal facets during the growth of gold nanorods. This is significant because it provides new insights into the mechanism of particle growth (in particular on the kinetics of anisotropy evolution) and presents new opportunities for the design of reaction conditions that facilitate the controlled synthesis of non-equilibrium particle shapes. To the best of our knowledge it is the first time that surface reconstruction could be demonstrated on facets of solution-grown gold nanocrystals. Second, the identification of synthesis conditions that facilitate the reduction of shape-regulating surfactants by 90% by means of solvent isotopic replacement or the use of Gemini-surfactants as alternative (and more efficient) shape-regulating surfactant systems. Finally, a new synthetic technique was devised based on the use of imidazolium-based ionic liquids that results in unprecedented nanorod yields and anisotropy and completely circumvents the use of surfactant additives to induce anisotropic growth. Three manuscripts have been published or submitted and one patent application is in preparation. The interaction with the hosting group of Professor Martin Moeller has stimulated several education projects that focus on graduate and undergraduate education. For example the PI is currently working with his former hosting group to establish an NSF-funded student exchange program that will facilitate the mutual exchange of students at the Institute of Technical and Macromolecular Chemistry at RWTH Aachen and the Department of Materials Science and Engineering at Carnegie Mellon University.
Publications
- ’Structural Evolution of Gold Nanorods during Controlled Secondary Growth’. Langmuir 2007, 23, 10307-10315
H. Keul, M. Moeller, M. R. Bockstaller
