CAREER: Education and Research in Nanomaterials Degraduation: The Road to Molecular Fatigue Studies

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The promise of revolutionary technologies has driven an aggressive investment in the science of nanomaterials. However, the ability to effectively utilize these materials is ultimately limited by how they degrade and fail. In this grant four families of nanomaterials that have been shown to be susceptible to fatigue degradation (brittle nanomaterials, ductile nanomaterials, organic monolayers, and macromolecules) will be characterized using electron microscopy and mechanically tested under monotonic and fatigue loading conditions using novel sample preparation and testing techniques with the ultimate goal of identifying the mechanisms underlying damage accumulation in these nanomaterials. Recent studies suggest that nanoscale materials can accumulate fatigue damage, but how and why such damage accumulates is unknown. As nanotechnology continues to evolve, it will be essential to understand the fatigue behavior of ever smaller structures, such as macromolecules and metallic nanowires, in order to avoid unanticipated, in-service failures. The initial phase of the program will develop techniques for the manipulation and selection of nanomaterials for mechanical testing. These techniques will characterize the fatigue behavior of Si nanowires and establish the deformation and fatigue behavior of single and polycrystalline metal nanowires of elemental Au and Ni. The established techniques will then be used to evaluate the fatigue behavior of assemblies of macromolecules by testing organic monolayer-coated Si nanowires. Finally, molecular fatigue will be explored during fatigue testing of carbon nanotubes. The nanowires and macromolecules to be studied are currently in development for a multitude of applications including electronics, sensors, and nanomechanical components and structures, and the establishment of a methodology for testing and identification of the mechanisms of fatigue in these materials will constitute a significant contribution to the field. This integrated education and basic research program will introduce students to nanoscience research and related experimental techniques. Underrepresented minority and women will be recruited for these positions to complement the already diverse lab group of the PI (80% women and/or underrepresented minorities). The results of this interdisciplinary research program will be disseminated via peer-reviewed journal publications and conference presentations to materials scientists, engineers, and physicists. The most effective materials characterization techniques developed in this program will be codified by proposing internationally recognized standards through the American Society for Testing and Materials (ASTM) task group co-chaired by the PI. Finally, a series of educational videos with supporting classroom materials will be produced for secondary schools, targeting the 7th through 12th grades. This multimedia package will be produced at the Penn State Public Broadcasting System station for distribution through their video streaming website and national educational video internet sites.