Highly Thermally Conductive and Mechanically Strong Graphene Fibers: From Molecular Orientation to Macroscopic Ordering

非技术描述：最近开发了一种由二维石墨烯片组装的新型碳纤维，其具有更高的热导率，但与传统碳纤维相比，其机械性能较差。石墨烯纤维的内部结构尚未得到很好的表征，并且对热机械性能的伴随影响尚未完全了解。该项目的目标是对纤维内部结构的基本理解，重点是分子取向和宏观有序性，并建立工艺-结构-性能的相关性。这些见解可能有助于开发高性能石墨烯纤维，并释放其技术应用潜力，例如，作为纤维增强复合材料的结构部件。新的纤维结构和性能、具有成本效益和环境友好的生产以及劳动力发展对于碳纤维行业的创新和制造竞争力至关重要。该项目吸引高中生、本科生和研究生参与研究。通过与当地社区的合作和学术外联活动，特别努力让代表性不足的高中生群体参与进来（包括Summer@Rensselaer）。技术支持：所提出的项目是基于碳纤维的传统智慧，其中纤维结构，特别是石墨烯片的分子取向，石墨域及其宏观有序性决定了机械强度，杨氏模量，和热/电性能。为了实现对纤维结构的基本理解并建立工艺-结构-性质相关性，在流体流动辅助组装期间研究氧化石墨烯胶体溶液和前体氧化石墨烯纤维的分子取向。石墨烯纤维的宏观有序化通过制造后碳化和石墨化来控制。它们对热机械性能的影响正在探索中。通过控制流体流动辅助组装过程和优化纤维结构，可以显着改善宏观石墨烯纤维的性能。二维石墨烯片的微流体使能组装可以使制造高性能碳纤维的新科学成为可能。

NON-TECHNICAL DESCRIPTION: A new type of carbon fibers assembled from two-dimensional graphene sheets was recently developed with higher thermal conductivity, but with inferior mechanical properties in comparison to conventional carbon fibers. The internal structure of the graphene fibers is not well characterized and the concomitant impact on thermal-mechanical properties are not fully understood. This project targets fundamental understanding of the inner fiber structure with a focus on molecular orientation and macroscopic ordering and establishing the process-structure-property correlation. These insights may enable the development of high performance graphene fibers and unlock their potential for technology applications, e.g., as structural components in fiber-reinforced composites. New fiber structures and properties, cost-effective and environmentally-benign production, and workforce development are critical for competitiveness in innovation and manufacturing in carbon fiber industries. This project engages high-school, undergraduate and graduate students in research. Special efforts are made to involve underrepresented groups of high-school students through collaborations with local communities and academic outreach activities (including Summer@Rensselaer).TECHNICAL DETAILS: The proposed project is based on the conventional wisdoms for carbon fibers in which the fiber structure, particularly molecular orientation of graphene sheets, graphitic domains and their macroscopic ordering determine mechanical strength, Young's modulus, and thermal/electrical properties. To achieve a fundamental understanding of the fiber structure and establish the process-structure-property correlation, molecular orientation of the graphene oxide colloidal solution and the precursor graphene oxide fiber is investigated during fluid flow-assisted assembly. Macroscopic ordering of the graphene fibers is controlled by post fabrication carbonization and graphitization. Their impact on thermal-mechanical properties are being explored. By controlling the fluid flow-assisted assembly process and optimizing fiber structures, properties of the macroscopic graphene fibers can be dramatically improved. The microfluidics-enabled assembly of two-dimensional graphene sheets may enable new science for fabricating high performance carbon fibers.