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

石墨烯是碳的一种二维(2D)形式，自2004年发现以来，由于其惊人的电学、机械和热学性质，引起了极大的兴奋。然而，实现石墨烯大规模可制造性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采用。石墨烯气凝胶是一类由2D石墨烯薄片共价交联形成三维(3D)结构的材料，在很大程度上保留了其石墨烯构建块的许多非凡特性，但尺寸仅受合成过程中使用的容器的限制。在这项工作中，将研究在重力(地球上)和微重力(国际空间站)条件下基于石墨烯的水凝胶合成。通过在国际空间站进行微重力实验，将阻止重力驱动的过程，如沉积和浮力驱动的对流，并将首次分离和研究有助于石墨烯气凝胶组装的潜在现象(例如随机布朗运动)。这一合作计划还旨在接触到小学生、本科生、研究生和普通公众，以提高对纳米技术和航空航天工程领域以及学术界职业生涯的认识。为了扩展空间产生的气凝胶的知识，我们将比较微重力合成的石墨烯气凝胶和地球合成的气凝胶的性质。目标有两个：(1)研究在重力存在下石墨烯气凝胶(GA)合成的生长行为(交联、团聚、干燥)；(2)研究和解释基于微重力的合成对气体的三维(3D)细观结构和多种物理性质(热传输、机械行为和电学特性)的影响。最终，这项工作将为石墨烯气凝胶(和其他气凝胶)的工程设计奠定基础，这些气凝胶具有高度均一的微结构和相应的优异的电、机械和热性能，使各种地球和空间应用得以实现，如超轻结构材料、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能会使国际空间站的研究人员能够直接使用材料和设备，并用于未来的太空任务。这一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智力优势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.