expansion coefficient in a wide temperature range. [2] CFs can not only be used as efficient thermal-management materials to maintain the functionality and reliability of microelectronic components with high heat flux, but also be used as high-performance composites for thermal protection of flight devices in the aerospace field. [3] In spite of their wide uses, the specific pitch-based CFs are the only commercial species of highly thermally conductive CFs with high cost. [4] As a comparison, the other commercial PAN-based CFs have strong mechanical properties but poor thermal conductivity due to their limited graphitic crystallinity, determining their confined application as lightweight structural materials. [2a,5] In this context, it is necessary to expand alternative sources of highly thermally conductive fibers beyond the sole pitch-based CFs. [2b,6] An intuitive option is translating PAN-based CFs to highly thermally conductive species, but remains a forbidden task that is challenged by the intrinsic incompatibility between the 1D topology of linear polymers and the 2D topology of target graphitic crystallinity. [5b,7] The thermal conductivity of graphitic materials is determined by their complicated nano textures and spans a wide range from ≈6 W m −1 K −1 in glassy carbon to ≈2000 W m −1 K −1 in pyrolytic graphite at room temperature. [8] In principle, the Highly thermally conductive carbon fibers (CFs) have become an important material to meet the increasing demand for efficient heat dissipation. To date, high thermal conductivity has been only achieved in specific pitch-based CFs with high crystallinity. However, obtaining high graphitic crystallinity and high thermal conductivity beyond pitch-CFs remains a grand challenge. Here, a 2D-topology-seeded graphitization method is presented to mediate the topological incompatibility in graphitization by seeding 2D graphene oxide (GO) sheets into the polyacrylonitrile (PAN) precursor. Strong mechanical strength and high thermal conductivity up to 850 W m −1 K −1 are simultaneously realized, which are one order of magnitude higher in conductivity than commercial PAN-based CFs. The self-oxidation and seeded graphitization effect generate large crystallite size and high orientation to far exceed those of conventional CFs. Topologically seeded graphitization, verified in experiments and simulations, allows conversion of the non-graphitizable into graphitizable materials by incorporating 2D seeds. This method extends the preparation of highly thermally conductive CFs, which has great potential for lightweight thermal-management materials.

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Natural materials teach that mechanical dissipative interactions relieve the conflict between strength and toughness and enable fabrication of strong yet tough artificial materials. Replicating natural nacre structure has yielded rich biomimetic materials; however, stronger interlayer dissipation still waits to be exploited to extend the performance limits of artificial nacre materials. Here, we introduce strong entanglement as a new artificial interlayer dissipative mechanism and fabricate entangled nacre materials with superior strength and toughness, across molecular to nanoscale nacre structures. The entangled graphene nacre fibers achieved high strength of 1.2 GPa and toughness of 47 MJ/m3, and films reached 1.5 GPa and 25 MJ/m3. Experiments and simulations reveal that strong entanglement can effectively dissipate interlayer energy to relieve the conflict between strength and toughness, acting as natural folded proteins. The strong interlayer entanglement opens up a new path for designing stronger and tougher artificial materials to mimic but surpass natural materials.