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

革命性技术的前景推动了对纳米材料科学的积极投资。然而，有效利用这些材料的能力最终受到它们如何降解和失效的限制。在这项资助中，四个已被证明易受疲劳降解影响的纳米材料家族（脆性纳米材料，韧性纳米材料，有机单层和大分子）将使用电子显微镜进行表征，并在单调和疲劳载荷条件下使用新型样品制备和测试技术进行机械测试，最终目标是确定这些纳米材料中损伤累积的机制。 最近的研究表明，纳米材料可以累积疲劳损伤，但这种损伤如何以及为什么累积尚不清楚。随着纳米技术的不断发展，了解更小结构（如大分子和金属纳米线）的疲劳行为至关重要，以避免意外的使用中故障。该计划的初始阶段将开发用于机械测试的纳米材料的操作和选择技术。这些技术将表征Si纳米线的疲劳行为，并建立元素Au和Ni的单晶和多晶金属纳米线的变形和疲劳行为。建立的技术，然后将被用来评估疲劳行为的大分子组件通过测试有机单层涂层硅纳米线。最后，分子疲劳将在碳纳米管的疲劳测试过程中进行探索。纳米线和大分子的研究目前正在开发的多种应用，包括电子，传感器和纳米机械组件和结构，并建立一种方法来测试和识别这些材料的疲劳机制将构成一个显着的贡献领域。这个综合教育和基础研究计划将向学生介绍纳米科学研究和相关的实验技术。这些职位将招募代表性不足的少数族裔和女性，以补充PI已经多元化的实验室团队（80%为女性和/或代表性不足的少数族裔）。这项跨学科研究计划的结果将通过同行评审的期刊出版物和会议报告传播给材料科学家，工程师和物理学家。本计划中开发的最有效的材料表征技术将通过由PI共同主持的美国试验与材料协会（ASTM）工作组提出国际公认的标准进行编纂。最后，将为中学制作一系列教育录像，并提供辅助教材，对象是7至12年级。这个多媒体包将在宾夕法尼亚州公共广播系统站制作，通过他们的视频流网站和国家教育视频互联网网站分发。

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.