CAREER: Deformation and interfacial slip in two-dimensional material heterostructures

这个教师早期职业发展（Career）项目将探索摩擦的基本极限，以及如何利用由二维材料组成的原子膜的纳米级界面上的滑移。膜的一个重要功能是通过引入界面滑移或面外皱缩来减轻应力。二维界面也显示出新兴的纳米级特性，如超润滑，其中摩擦减少了100倍。然而，界面上的滑动和超润滑如何影响由多种材料异质结构制成的纳米级膜的力学性能还不是很清楚。这项研究的成功将导致电子材料的设计，积极利用滑移和变形，变得比最先进的可拉伸技术（如硅微机电系统或有机电子）柔韧性高10-100倍。由2D材料制成的可滑动设备在可穿戴电子产品中应用于低占地面积，低功耗传感器，可调谐信号处理器或能量收集系统。作为项目的一部分，PI还将创建一个基于项目的教育推广活动，学生将设计一个激光表演，并将其送到主要是少数民族人口的学校，以及为代表性不足的群体举办的STEM夏令营。PI将继续为本科生（包括代表性不足的少数民族）创造研究指导机会，并引入一门新的基于项目的纳米工程课程。二维材料异质结构中共价键的缺乏和范德华界面的不对称结构导致了材料的超润滑和层间滑动。本课程将研究在剪切、弯曲和拉伸下，层间摩擦和滑移对二维异质结构的影响。目的1将通过原子尺度模拟和多尺度建模，为非相称异质结构界面上的摩擦、粘附、滑移和超润滑的量化奠定理论基础。目的2将通过由二维异质结构构建的滑动微柱和横向力显微镜测量力，实验探索剪切作用下不适应界面的摩擦。目标3和目标4将分别研究二维薄膜和共振鼓面中滑移的影响。这些结果有望揭示层间排列和超润滑之间的相互作用，当光滑滑动或粘滑发生时，以及滑移介导的纳米力学尺度规律和模量。这些新知识将用于预测和设计二维异质结构原子膜的柔韧性，处于技术和应用的前沿。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development (CAREER) Program project will explore the fundamental limits of friction and how to utilize slip at nanoscale interfaces in atomic membranes composed of two dimensional materials. An important capability of membranes is to relieve stress through the introduction of interfacial slip or out-of-plane crumpling. Two-dimensional interfaces also display emergent nanoscale properties like superlubricity where the friction decreases by a factor of 100. Yet, it is not well understood how slip and superlubricity at interfaces affects the mechanics of nanoscale membranes made from heterostructures of multiple materials. The success of this study will lead to the design of electronic materials which actively utilize slip and deformation to become 10-100 times more pliable than state of the art stretchable technologies like silicon microelectromechanical systems or organic electronics. Slippable devices made from 2D materials have applications as low-footprint, low power sensors, tunable signal processors, or energy harvesting systems in wearable electronics. As part of the project, the PI will also create a project-based educational outreach activity in which students will design a laser light show and deliver them to schools with primarily minority populations and summer STEM camps for underrepresented groups. The PI will continue creating research mentoring opportunities for undergraduates including underrepresented minorities and introduce a new project-based nanoscale engineering course.The lack of covalent bonds and the incommensurate structure at van der Waals interfaces in 2D materials heterostructures leads to superlubricity and easy slip between layers. This program will examine the impact of interlayer friction and slip on 2D heterostructures under shear, bending, and tensioning. Objective 1 will build a theoretical foundation to quantify friction, adhesion, slip and superlubricity at incommensurate heterostructure interfaces through atomic scale simulation and multiscale modeling. Objective 2 will experimentally probe the friction of incommensurate interfaces under shear by sliding micropillars built from 2D heterostructures and measuring the forces with lateral force microscopy. Objectives 3 and 4 will respectively study the impact of slip in crumpled 2D membranes and resonant drumheads. These results are anticipated to reveal the interplay between interlayer alignment and superlubricity, when smooth sliding or stick-slip occurs, and slip-mediated nanomechanical scaling laws and moduli. The new knowledge will be used to predict and design the pliability of 2D heterostructure atomic membranes lying at the forefront of technologies and applications.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.