DMREF: A Fundamental Approach to Study the Effect of Structural and Chemical Composition in Functionalized Graphene Materials

该项目的中心目标是通过以多尺度和协同的方式结合理论、建模和实验来建立材料设计的范式转变，以最大限度地提高纳米复合材料的强度和韧性，这种材料模仿使用石墨烯氧化物的天然珍珠层的性能。预计具有最佳重叠几何结构的石墨烯氧化物薄片将通过可调化学结合在一起，模拟珍珠层。具体地说，这项研究将通过对单个原子薄片及其交联元的强度和刚度的研究来表征多层纳米复合材料系统的变形机制。本项目旨在加深对范德华相互作用、氢键以及化学交联、构象和几何组装在调节基于石墨烯氧化物的纳米复合材料的力学行为中所起的作用的基本了解。功能化石墨烯片材和宏观氧化石墨烯材料的力学性能将通过一系列迭代的合成-组装-建模循环进行优化。基于MEMS技术和原子力显微镜的新型纳米力学测试方法将被应用于测量具有砖瓦状分层结构的少层石墨烯氧化物材料的力学行为。将探索新的交联剂，如硫醇胺，通过共价键的断裂和重整，显著改善剪切相互作用的控制。将探索不同层之间的几何重叠和板材的构象。原位电子显微镜力学测试，以获得多个长度尺度上的原子和微尺度特征，再加上使用从头计算和半经验方法的计算建模，将量化控制载荷传递机制的界面强度和变形。开发的洞察力将被用于指导宏观纳米复合材料的合成，该材料利用石墨烯的强度和受自然启发的分级组装结构。预计预测和定制基于石墨烯的纳米复合材料力学性能的标准的开发将适用于广泛的纳米复合材料，并将优化具有分层结构的材料的设计过程，这些材料包括刚性构建块和延展性交联元素。这些下一代合成材料对于航空航天、卫星、汽车、军事和医疗保健行业的进步至关重要。这项研究还将作为研究生和博士后研究员在基于结构的材料设计的关键前沿以及在合成、建模和分层测量领域的跨学科科学研究艺术方面的优秀培训平台。

The central goal of this project is to establish a paradigm shift in material design by combining theory, modeling, and experimentation in a multiscale and synergistic manner to maximize the strength and toughness of nanocomposite materials that emulate the performance of natural nacre using graphene oxide. It is expected that graphene oxide sheets with optimal overlap geometry, bonded together by tunable chemistry, will mimic nacre. Specifically, this research will lead to characterization of the deformation mechanisms of multilayer nanocomposite systems through studies of the strength and stiffness of both the individual atomically thin sheets as well as their crosslinking elements. This project aims to develop a fundamental understanding of the roles that van der Waals interactions, hydrogen bonds, and chemical crosslinking, conformation, and geometrical assembly play in modulating the mechanical behavior of nanocomposite materials based on graphene oxide. The mechanical performance of functionalized graphene sheets and macroscopic oxidized-graphene materials will be optimized through a series of iterative synthesis-assembly-modeling cycles. Novel nanoscale mechanical testing methods based on MEMS technologies and AFM will be applied to measure the mechanical behavior of few-layer graphene oxide materials with "brick-and-mortar" like hierarchical structures. New crosslinking chemistries, such as thiol-amines, will be explored to impart significant improvements in controlling shear interactions through covalent bond breaking and reformation. Varying geometrical overlap between layers and conformations of the sheets will be explored. In-situ electron microscopy mechanical testing, to yield atomic and micro-scale characteristics on multiple length scales, coupled with computational modeling using ab initio and semi-empirical methods, will quantify the interface strength and deformation governing load-transfer mechanisms. The developed insight will then be used to guide the synthesis of a macroscopic nanocomposite material that takes advantage of the strength of graphene and the hierarchically assembled structures inspired by Nature.It is expected that the development of criteria for predicting and tailoring the mechanical properties of graphene oxide-based nanocomposite materials will be transferable to a wide range of nanocomposites and will optimize the design process of materials with hierarchical structure that incorporate stiff building blocks and ductile crosslinking elements. These next-generation synthetic materials are essential for advances in the aerospace, satellite, automotive, military, and healthcare industries. The research also will serve as an excellent training platform for graduate students and postdoctoral fellows in the critical frontier of structure-based material design and in the art of interdisciplinary scientific research in the areas of synthesis, modeling, and hierarchical measurements.