US-Ireland R&D Partnership: Mechanics of the Formation and Function of 2D Material Pleats

实现纳米材料巨大潜力的一个核心挑战是，它们难以控制、操纵，也难以大规模生产成有用的结构和设备。这在一定程度上是由于小尺寸，它们相互粘在一起的倾向，以及它们对热振动的敏感性。因此，了解这些效应背后的纳米级力是很重要的，包括附着力和摩擦力。发展这种知识的关键在于理解和利用这些力量的有益方面。其中一个例子是自组装现象，纳米级材料将自己组织成有序的结构。该奖项支持的研究旨在了解在这种特别引人注目的行为中，力是如何协同作用的：原子薄的二维材料的长折叠褶的自发形成，可以用一个简单的放大镜看到。实验和模拟将被用来了解是什么控制和驱动这个过程，由一个跨学科的合作者团队进行，他们将结合他们独特和理想的专业知识来解决这个问题。目标是揭示控制这些褶皱形成的机械原理。这项工作具有广泛的科学和技术影响，因为它侧重于这些材料的基本力学，但着眼于控制它们的组装和构造成有用的结构和设备。该奖项还将通过培训本科生、研究生和博士后研究人员来支持教育推广。这将包括在合作实验室之间进行指导的国际人员交流；让K-12学生和公众参与外展活动；并为研究人员开发了一个关于这些材料的纳米级力学的在线短期课程。二维材料褶皱是最近发现的长而折叠的结构。它们的形成是通过用纳米压头尖端刺穿衬底支撑的二维材料（如石墨烯）来触发的。接下来是二维材料的折叠带的后续生长，高达10微米。然而，人们对这些非凡结构的基本力学知之甚少。虽然已经开发了一个连续水平的模型，可以对褶皱的形成提供一些定性的见解，但对控制这种现象的机制还没有原子水平的理解。该项目通过对褶皱形成的力学及其形成后的力学特性进行自动信息调查来解决这一差距。要做到这一点，需要将材料合成、纳米力学表征、原子和粗粒度模拟结合起来。来自美国、爱尔兰共和国和英国北爱尔兰的跨学科合作团队将利用他们独特的专业知识组合来解决这个问题。主要目标是揭示控制褶皱成核、生长和与环境相互作用的基本机械原理。这项工作的长期、广泛的影响将是建立从广泛和不断增长的二维和薄材料阵列中制造有用设备的设计原则。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。

A central challenge in fulfilling the tremendous potential of nanoscale materials is that they are hard to control, manipulate, and mass-produce into useful structures and devices. This is in part due to the small size, their tendency to stick to one another, and their susceptibility to thermal vibrations. Thus, it is important to understand the nanoscale forces behind these effects, including adhesion and friction. The key to developing this knowledge lies in understanding and taking advantage of the beneficial aspects of these forces. One such case is the phenomenon of self-assembly, where nanoscale materials organize themselves into ordered structures. This award supports research which aims to understand how forces conspire in a particularly striking case of such behavior: the spontaneous formation of long, folded pleats of atomically thin, two-dimensional materials that can be seen with a simple magnifying glass. Experiments and simulations will be used to understand what controls and drives this process, conducted by an interdisciplinary team of collaborators who will combine their unique and ideal expertise to tackle the problem. The goal is to uncover the mechanical principles governing the formation of these pleats. The work has broad scientific and technological impact, as it focuses on the fundamental mechanics of these materials but with a view toward controlling their assembly and construction into useful structures and devices. The award will also support educational outreach by training undergraduate, graduate, and postdoctoral researchers. This will include mentored international personnel exchanges between the collaborators’ laboratories; engaging K-12 students and the public in outreach events; and developing an online short course for researchers about the nanoscale mechanics of these materials. Two-dimensional material pleats are long, folded structures that have been recently discovered. Their formation is triggered by puncturing a substrate-supported two-dimensional materials like graphene with a nanoindenter tip. This is followed by subsequent growth of a folded ribbon of the two-dimensional material, up to 10’s of micrometers. However, little is known about the fundamental mechanics of these remarkable structures. While a continuum-level model has been developed that gives some qualitative insight into pleat formation, there is no atomistic-level understanding of the mechanisms that govern the phenomenon. This project addresses this gap by performing an atomistically-informed investigation of the mechanics of pleat formation and their mechanical properties once formed. Doing this requires an effort that integrates material synthesis, nanomechanical characterization, and atomistic and coarse-grained simulations. An interdisciplinary team of collaborators from the US, the Republic of Ireland, and Northern Ireland, UK will use their unique combination of expertise to tackle this problem. The primary goal is to uncover the fundamental mechanical principles governing pleat nucleation, growth, and interaction with the environment. A long-term, broad impact of this work will be to establish design principles for fabricating useful devices from the wide and growing array of two-dimensional and thin 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.