Molecular Tailoring of Interfacial Fracture

这项资助的研究目标是建立分子尺度表面修饰与宏观界面粘合和断裂之间的基本关系。该研究计划将强调开发集成的、多尺度的实验和数值工具，以表征、建模并最终扩大对如何利用自组装单分子膜(SAM)来控制界面失效机制的理解，重点放在实验条件和分子水平模型可以直接相关的高应变率区域。通过高应变率激光诱导动态分层方法的进展，将实现对SAM中介界面的强度和韧性的实验评估。为了支持实验并深入了解界面失效过程，将开发、验证和应用结合分子动力学模型和连续体级多尺度内聚框架的高级建模工具。分子动力学和连续体级分层内聚模型的新集成将为分层事件中粘附性的分子剪裁提供重要的见解。该研究项目将具有重大的教育和技术影响。SAMS被越来越多地应用于广泛的技术应用中，包括MEMS中的润滑剂、微电子中的扩散障碍、附着力促进以及控制界面上的热传输。评估和预测自组装膜的粘合性能对于在这些和未来的应用中成功发挥作用至关重要。该研究项目将为两名研究生和一名暑期本科生提供培训，他们将受益于真正的多学科教育，即材料科学、固体力学和化学，并将有机会参加外联活动。

The research objective of this grant is to establish fundamental relationships between molecular scale surface modification and macroscale interfacial adhesion and fracture. The research program will emphasize the development of integrated, multiscale experimental and numerical tools to characterize, model, and ultimately expand understanding of how self-assembled monolayers (SAMs) can be exploited to control mechanisms of interfacial failure, with emphasis on the high strain rate regime at which experimental conditions and molecular-level models can be directly related. The experimental assessment of the strength and toughness of the SAM-mediated interfaces will be achieved through advances in high strain rate, laser-induced dynamic delamination methods. To support the experiments and provide insight on the interfacial failure processes, advanced modeling tools combining molecular dynamics models and a continuum-level multiscale cohesive framework will be developed, validated, and applied. The novel integration of MD and continuum-level cohesive models of delamination will deliver important insights on the molecular tailoring of adhesion properties in delamination events.The research project will have significant educational and technological impact. SAMs are increasingly used in a wide range of technological applications, including lubricants in MEMS, diffusion barriers in microelectronics, adhesion promotion, and for control of heat transport across interfaces. Assessing and predicting the adhesion properties of SAMs are critical for successful performance in these and future applications. This research project will provide training for two graduate students and one summer undergraduate research student, who will benefit from a truly multidisciplinary education in materials science, solid mechanics, and chemistry and will have the opportunity to participate in outreach activities.