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

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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.