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

二维材料是具有原子至纳米尺度厚度的层状材料。它们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，层之间的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。该项目的目标是获得对材料特性（包括成分、相和结晶度）对界面接触、粘附和摩擦的关键特性的影响的基本理解。这将产生广泛的技术影响，因为需要对分层材料进行研究，以优化和改变它们在依赖这些关键特性的应用中的使用。该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，从而促进科学进步;促进国家健康，繁荣和福利;并确保国防。该项目的研究目标将得到补充，重点是为代表性不足的群体的学生提供机会的活动，包括涉及加州默塞德大学的大量西班牙裔人口，并利用宾夕法尼亚大学的成功推广计划。该团队还将与大学前的观众接触，建立在PI的公众和青年参与的跟踪记录上。该项目将专注于过渡金属二硫属化物（包括二硫化钼）的纳米级界面接触，粘附和摩擦行为。 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进行，利用PI的独特功能。最佳匹配允许通过实验验证模拟，并通过模拟在原子分辨率的细节中充分探索实验结果。使用最近开发的技术涂覆有良好定义的、非线性过渡金属二硫属化物的探针尖端和衬底的可用性将使得能够隔离自配对和异质结构界面的组合物、相和结晶度的影响。这种新的方法将产生基本的洞察过渡金属二硫属化物接口的材料，设备和系统组成的这些material.This奖项反映了NSF的法定使命的合理和预测设计所需的机械性能，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.