Collaborative Research: Friction in Flatland - Contact, Adhesion, and Friction of 2D Materials

二维材料是具有原子到纳米级厚度的层状材料。它们正越来越多地被探索和用于利用材料的分层结构的多种应用。然而，层与层之间界面的性质仍然知之甚少，部分原因是与在非常小的长度尺度上直接测量这些性质相关的挑战。本项目的目标是从根本上了解材料特性，包括组成、物相和结晶度对界面接触、粘合和摩擦等关键特性的影响。这将产生广泛的技术影响，因为需要对层状材料进行研究，以优化和改变它们在依赖这些关键性能才能有效发挥作用的应用中的使用。这项研究的重点是与当前和新兴应用相关的层状材料，包括汽车、航空航天和电子行业中的应用，从而促进科学进步，促进国家健康、繁荣和福利，保障国防安全。该项目的研究目标将得到一些活动的补充，这些活动侧重于为代表不足的群体的学生提供机会，包括让加州大学默塞德分校的大量拉美裔人口参与进来，以及利用宾夕法尼亚大学成功的外展计划。该团队还将在PI公共和青年接触的记录的基础上，与大学前的观众接触。这个项目将集中在过渡金属二盐基化物的纳米级界面接触、粘合和摩擦行为，包括二硫化钼。对这些材料的研究将通过最佳匹配的原子力显微镜和加速分子动力学模拟来进行，利用PI的独特能力。最佳匹配允许通过实验验证模拟，并通过模拟以原子解析的细节充分探索实验结果。利用最新开发的技术，在探头尖端和衬底上涂覆定义明确的超薄过渡金属二卤化物，将能够隔离自配对和异质结构界面的成分、物相和结晶度的影响。这一新的方法将对过渡金属二卤化物界面的机械性能产生基本的见解，这些界面是合理和预测性设计材料、器件和由这些材料组成的系统所需的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Two-dimensional materials are layered materials having atomic- to nano-scale thickness. They are increasingly being explored and used for a multitude of applications that take advantage of the materials' layered structure. However, the properties of the interfaces between the layers are still poorly understood, due in part to challenges associated with direct measurement of such properties at very small length scales. The goal of this project is to obtain a fundamental understanding of the effect of material properties, including composition, phase, and crystallinity, on the critical properties of interfacial contact, adhesion, and friction. This will have broad technological impact, since investigation of layered materials is needed to optimize and transform their use in applications that rely on these critical properties to function effectively. The focus of this research is on layered materials that are relevant to current and emerging applications, including those in the automotive, aerospace, and electronics industries, thereby promoting the progress of science; advancing the national health, prosperity, and welfare; and securing the national defense. The research objectives of this project will be complemented by activities focused on providing opportunities for students from underrepresented groups, including involving the large Hispanic population at University of California Merced and leveraging successful outreach programs at University of Pennsylvania. The team will also engage with pre-college audiences, building on the PIs' track records of public and youth engagement.This project will focus on the nanoscale interfacial contact, adhesion, and friction behavior of transition metal dichalcogenides, including molybdenum disulfide. Research on these materials will be carried out through optimally-matched atomic force microscopy and accelerated molecular dynamics simulations, taking advantage of the unique capabilities of the PIs. Optimal matching allows simulations to be validated by experiments, and experimental findings to be fully explored in atomically-resolved detail by simulations. Availability of probe tips and substrates coated with well-defined, ultrathin transition metal dichalcogenides using recently developed techniques will enable isolation of the effects of composition, phase, and crystallinity for both self-mated and heterostructure interfaces. This novel approach will yield fundamental insights into the mechanical properties of transition metal dichalcogenide interfaces that are needed for rational and predictive design of materials, devices, and systems composed of these materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.