ISS: Collaborative Research: Examination of the Multi-physical Properties of Microgravity-synthesized Graphene Aerogels

石墨烯是一种二维形式的碳，自2004年被发现以来，由于其惊人的电学、机械和热性能，它引起了极大的兴奋。然而，石墨烯在实现大规模可制造性方面的困难阻碍了其在纳米电子、电池、传感和复合材料等目标应用中的大规模应用。石墨烯气凝胶是一类由二维石墨烯片共价交联成三维（3D）结构的材料，在很大程度上保留了石墨烯构建块的许多非凡特性，但仅受合成过程中使用的容器的大小限制。在这项工作中，将研究重力（在地球上）和微重力（在国际空间站，ISS）条件下石墨烯基水凝胶的合成。通过在国际空间站上的微重力实验，重力驱动的过程（如沉降和浮力驱动的对流）将被阻碍，并且有助于石墨烯气凝胶组装的潜在现象（如随机布朗运动）将首次被分离和研究。这项合作计划还旨在让小学生、本科生、研究生和公众提高对纳米技术和航空航天工程领域以及学术界职业的认识。为了扩展太空生产气凝胶的知识，我们将比较微重力合成的石墨烯气凝胶与地球合成的气凝胶的性质。目的有两个：(1)研究石墨烯气凝胶（GA）合成在重力存在之外的生长行为（交联、团聚、干燥）；(2)研究和解释微重力合成对气体三维细观结构和多物理性质（热输运、力学行为和电学特征）的影响。最终，这项工作将为石墨烯气凝胶（以及其他气凝胶）的工程设计奠定基础，这些气凝胶具有高度均匀的微观结构和相应的优越的电学、机械和热性能，从而实现各种各样的地球和空间应用，如超轻型结构材料、超级电容器和电池电极、储氢和水处理膜。此外，在国际空间站上生产气凝胶可以使国际空间站研究人员直接使用材料和设备，并用于未来的太空任务。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。

Graphene, a two-dimensional (2D) form of carbon, has generated extreme excitement since its discovery in 2004, due to its startling electrical, mechanical, and thermal properties. Yet, difficulties in realizing large-scale manufacturability of graphene has hindered mass adoption into target applications such as nanoelectronics, batteries, sensing and composites. Graphene aerogels, a class of materials made of 2D graphene sheets covalently crosslinked into a three-dimensional (3D) structure, largely retain many of the extraordinary properties of their graphene building blocks but are limited in size only by the container used during synthesis. In this work, graphene-based hydrogel synthesis in gravity (on Earth) and microgravity (on the International Space Station, ISS) conditions will be examined. Through experimentation in microgravity on the ISS, gravity-driven processes such as sedimentation and buoyancy-driven convection will be hindered, and underlying phenomena contributing to graphene aerogel assembly (e.g., random Brownian motion) will be isolated and investigated for the first time. This collaborative program also aims to reach elementary school students, undergraduate students, graduate students and the general public to raise awareness of the fields of nanotechnology and aerospace engineering, as well as careers in academia. To extend the knowledge of space-produced aerogel, we will compare the properties of microgravity-synthesized graphene aerogels to Earth-synthesized aerogels. The objectives are two-fold: (1) to study the growth behavior (cross-linking, agglomeration, drying) of graphene aerogels (GA) synthesis outside the presence of gravity; and (2) to examine and explain the influence of microgravity-based synthesis on the 3-dimensional (3D) mesostructure and multi-physical properties (thermal transport, mechanical behavior, and electrical characteristics) of GAs. Ultimately, this work will provide the foundation for engineering of graphene aerogels (and other aerogels) with highly homogenous microstructures and correspondingly superior electrical, mechanical, and thermal properties to enable a wide variety of Earth and space applications, such as, ultra-lightweight structural materials, supercapacitor and battery electrodes, hydrogen storage, and water treatment membranes. In addition, in-space production of aerogels on the ISS may enable direct use of materials and devices by ISS researchers and for future space missions.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.