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

非技术描述：一种由二维石墨烯薄片组装而成的新型碳纤维最近被开发出来，它具有更高的导热系数，但与传统的碳纤维相比，其机械性能较差。石墨烯纤维的内部结构没有得到很好的表征，对热机械性能的影响也没有完全了解。这个项目的目标是对纤维内部结构的基本了解，重点放在分子取向和宏观有序上，并建立工艺-结构-性能的关联。这些见解可能会使高性能石墨烯纤维的开发成为可能，并释放其技术应用的潜力，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、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在创新和制造方面的竞争力至关重要。这个项目吸引了高中生、本科生和研究生参与研究。通过与当地社区的合作和学术推广活动(包括Summer@Rensselaer)，特别努力让未被充分代表的高中生群体参与进来。技术细节：拟议的项目基于碳纤维的传统智慧，在这些智慧中，纤维结构，特别是石墨烯片材的分子取向、石墨烯微区及其宏观有序性决定了机械强度、杨氏模量和热/电性能。为了对纤维结构有一个基本的了解，并建立工艺-结构-性能之间的关系，研究了流体辅助组装过程中氧化石墨烯胶体溶液和前驱体氧化石墨烯纤维的分子取向。石墨烯纤维的宏观有序化受后加工、碳化和石墨化的控制。人们正在探索它们对热机械性能的影响。通过控制流体流辅助组装过程和优化纤维结构，可以显著提高宏观石墨烯纤维的性能。利用微流控技术组装二维石墨烯薄片可能会为制造高性能碳纤维提供新的科学依据。

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.