Abstract
Van der Waals (vdW) materials consisting of two-dimensional (2D) building blocks have strong in-plane covalent bonding and weak interlayer interactions. While monolayer 2D materials exhibit impressive fracture resistance, as demonstrated in hexagonal boron nitride (h-BN), preserving these remarkable properties in vdW materials remains a challenge. Here we reveal an anomalous mechanical interlayer coupling that involves interlayer-friction toughening and edge-reconstruction embrittlement during the fracture of multilayer h-BN. Both asynchronous and synchronous fracture modes and their flaw-size dependence are identified. Edge reconstruction in the synchronous fracture mode can eliminate a toughening mechanism induced by lattice asymmetry in monolayer h-BN, leading to embrittlement of the multilayer h-BN, while the asynchronous fracture mode results in greater fracture resistance. Such findings will provide fundamental guidelines for engineering interlayer interactions in vdW materials including heterostructures and layered architectures for better mechanical and functional performances.
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Data availability
The data that support the findings of this study are available from the corresponding authors on reasonable request.
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The code that supports the findings of this study is available from the corresponding authors on reasonable request.
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Acknowledgements
We acknowledge the financial support by the US Department of Energy, Office of Basic Energy Sciences under grant DE-SC0018193. H.G. acknowledges a start-up grant from Nanyang Technological University (002479-00001) and Agency for Science, Technology and Research (A*STAR). During the revision of this manuscript, the affiliation of H.G. has changed to Mechano-X Institute, Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing, China.
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Z.S., B.Z. and Y.Y. conceived the project. B.Z., Y.Y. and J.L. designed the experiments and analysed the data. Z.S. and H.G. performed simulations and analysed the results. G.G., Y.H. and D.T. performed TEM analysis. Q.F., B.S., D.S., Q.A. and X.Z. helped with the sample preparation and characterization. Y.Z. performed digital image correlation. T.T. and K.W. performed material synthesis. Z.S., B.Z., Y.Y. supervised by N.P.P., B.W.S., J.L. and H.G. drafted the manuscript with inputs, discussion and approval from all co-authors.
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Nature Materials thanks Zonghoon Lee, Arend van der Zande and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Supplementary Sections 1–9, Figs. 1–11, Tables 1–3 and References.
Supplementary Video 1
In situ tension of MBN ribbon with no precrack.
Supplementary Video 2
In situ tension of MBN ribbon with precrack length of ~0.61 μm.
Supplementary Video 3
In situ tension of MBN ribbon with precrack length of ~0.86 μm.
Supplementary Video 4
In situ tension of MBN ribbon with precrack length of ~1.65 μm.
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Song, Z., Zhang, B., Yang, Y. et al. Flaw-size-dependent mechanical interlayer coupling and edge-reconstruction embrittlement in van der Waals materials. Nat. Mater. 24, 1554–1560 (2025). https://doi.org/10.1038/s41563-025-02194-x
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DOI: https://doi.org/10.1038/s41563-025-02194-x
