Novel Strategies for Nanoparticle Assemblies

1. 60 nm Novel Strategies for Nanoparticle Assemblies Stephanie L. Brock, Wayne State University,DMR-0094213 Recent NSF-supported work published in the journal Science (2005, 307, 397) describes how to prepare assemblies of quantum dot nanoparticles without losing the unique, size-dependent optical properties that are the hallmark of nanoscale semiconductors. The trick is to obtain a low-density, fractal-like structure of particles, wherein the particles are physically connected, yet remain dimensionally isolated. Macrostructure (left) and microstructure (right) of a CdS aerogel. The difference is scales is 106 In this work, nanoparticles are assembled by a sol-gel strategy, and the polymeric wet-gel structure is retained by supercritical drying, yielding an aerogel. This technique has been applied to CdS, CdSe, ZnS and PbS, providing the first examples of chalcogenide-based aerogels. Importantly, they all behave optically just like the individual nanoparticles! This methodology may be appropriate for assembling a wide range of materials. The chalcogenide aerogels produced here are currently being investigated for photovoltaic and sensing applications

2. Novel Strategies for Nanoparticle Assemblies Stephanie L. Brock, Wayne State University,DMR-0094213 Introducing Nanomaterials to Undergrads: Getting students involved in Nanochemistry early in their studies is important for the development of this new interdisciplinary science, but is not addressed in traditional Chemistry curricula. Over the course of the CAREER proposal, three new laboratories and several lecture segments focused on nanomaterials have been integrated into the undergraduate inorganic courses at Wayne State. Additionally, a total of ten undergraduate students have participated in original research projects in the Brock lab. In the process, these students have acquired hands-on experience with state of the art instrumentation, including X-ray powder diffraction, and electron and atomic force microscopes. Michele Tague, an undergraduate from Keene State College, NH, and participant in the NSF Summer Research Program in Solid State Chemistry, seals a sample in a glass ampoule.

3. Novel Strategies for Nanoparticle Assemblies Stephanie L. Brock, Wayne State University,DMR-0094213 Laboratories on ferrofluids, metal chalcogenide nanoparticles, and sol-gel chemistry have been added to the senior level undergraduate inorganic chemistry lab/lecture course. Additionally, modules on solid state structure, band theory, and physical properties of nanomaterials have been incorporated in both the sophomore and senior level inorganic chemistry courses. A total of ten undergraduates (including three current students and a 2004 summer fellow, Michele Tague) contributed to the NSF funded research. The most recent graduate, Christina Sweeney, participated in NSF Summer Research Program in Solid State Chemistry in 2004, working in the lab of Joanna Aitzenburg at Lucent Technologies. She is now a first year graduate student at Northwestern University and first author on a recently submitted manuscript.