Synthetic structural materials with exceptional mechanical performance suffer from either large weight and adverse environmental impact (for example, steels and alloys) or complex manufacturing processes and thus high cost (for example, polymer-based and biomimetic composites)1,2,3,4,5,6,7,8. Natural wood is a low-cost and abundant material and has been used for millennia as a structural material for building and furniture construction9. However, the mechanical performance of natural wood (its strength and toughness) is unsatisfactory for many advanced engineering structures and applications. Pre-treatment with steam, heat, ammonia or cold rolling10,11,12,13,14,15,16,17,18,19,20,21 followed by densification has led to the enhanced mechanical performance of natural wood. However, the existing methods result in incomplete densification and lack dimensional stability, particularly in response to humid environments14, and wood treated in these ways can expand and weaken. Here we report a simple and effective strategy to transform bulk natural wood directly into a high-performance structural material with a more than tenfold increase in strength, toughness and ballistic resistance and with greater dimensional stability. Our two-step process involves the partial removal of lignin and hemicellulose from the natural wood via a boiling process in an aqueous mixture of NaOH and Na2SO3 followed by hot-pressing, leading to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres. This strategy is shown to be universally effective for various species of wood. Our processed wood has a specific strength higher than that of most structural metals and alloys, making it a low-cost, high-performance, lightweight alternative.

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We thank R. Briber for suggestions and R. J. Bonenberger for help with mechanical tests. We acknowledge the support of the Maryland NanoCenter and its AIMLab. J.S. acknowledges financial support from the China Scholarship Council.

Author information

Author notes

    • Jianwei Song
    • , Chaoji Chen
    • , Shuze Zhu
    •  & Mingwei Zhu

    These authors contributed equally to this work.


  1. Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA

    • Jianwei Song
    • , Chaoji Chen
    • , Mingwei Zhu
    • , Jiaqi Dai
    • , Yiju Li
    • , Yudi Kuang
    • , Yongfeng Li
    • , Yonggang Yao
    • , Amy Gong
    •  & Liangbing Hu
  2. Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, USA

    • Shuze Zhu
    • , Upamanyu Ray
    • , Nelson Quispe
    • , Hugh A. Bruck
    • , Zheng Jia
    •  & Teng Li
  3. Department of Aerospace Engineering, University of Maryland, College Park, Maryland 20742, USA

    • Ulrich H. Leiste
  4. Forest Products Laboratory, USDA Forest Service, Madison, Wisconsin 53726, USA

    • J. Y. Zhu
  5. Department of Mechanical Engineering, University of California Merced, Merced, California 95343, USA

    • Azhar Vellore
    •  & Ashlie Martini
  6. Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA

    • Heng Li
    •  & Marilyn L. Minus


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J.S., C.C., S.Z. and M.Z. contributed equally to this work. L.H., J.S., C.C. and M.Z. contributed to the initiating idea. J.S. and C.C. contributed to the wood densification and mechanical measurements. Yo.L., U.R., Z.J., N.Q., U.H.L., H.A.B. and T.L. contributed to the mechanical tensile and ballistic tests. J.D. and Y.K. contributed to the 3D illustrations. Yi.L., C.C., Y.Y. and A.G. contributed to characterization via SEM. J.Y.Z. performed the compositional analysis. A.V. and A.M. contributed to the indentation and scratch hardness tests. S.Z. and T.L. contributed to both mechanical simulations and analysis. H.L. and M.L.M. contributed to XRD measurement and analysis. T.L., L.H., J.S. and C.C. contributed to the writing of the paper. All authors contributed to commenting on the final manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Teng Li or Liangbing Hu.

Reviewer Information Nature thanks A. Cloutier, S. Eichhorn and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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  1. 1.

    High-speed slow motion videos of ballistic tests

    Top: natural wood; Middle: monolayer densified wood; Bottom: laminated densified wood.

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