In this project supported by the Analytical and Surface Chemistry Program, Professor Richard Crooks and coworkers at Texas A&M University will synthesize and characterize dendrimer-encapsulated metal particles. The potential advantage of these materials is convenient access to nanometer-sized metal particles, on the order of 1-3 nanometers, having both high monodispersity and good stability. These nanomaterials are to be prepared by a two step process. First, the dendrimer is exposed to a metal ion-containing solution. This results in complexation between the metal ions and ligands within the dendrimer. The second step involves chemical reduction of the organic/inorganic composite, which results in formation of an intradendrimer metal nanoparticle. Each dendrimer acts as a discreet nanoreactor, and only those metal ions within the dendrimer coalesce into the resulting nanoparticle. This means that in principle every nanoparticle will contain the same number of metal atoms. This is significant because at the present time there are few methods available for preparing monodisperse metallic metal clusters in the 1-3 nm size range that are both surface active and soluble in many solvents. This size range is interesting for a number of reasons, but mainly because it is the range over which metal atoms undergo a transition from atomic to metallic properties.
Monodispersed metal nanoparticles have many applications to the technology sector. Applications include electronics, biomedical applications, fundamental studies of catalysis, and chemical and biological sensors. In addition to these broader impacts, this work invites many collaborative research projects. Catalytic properties of the dendrimer-encapsulated metal particles will be evaluated by colleagues at Trinity University. Commercial applications will be evaluated with colleagues at the Michigan Molecular Institute. Additional characterization of the nanoparticles is to be done with synchrotron experiments to be performed in South Korea. Finally, this proposal will support local high school students and undergraduates to work on the project during the summers.
