Article

A highly stretchable autonomous self-healing elastomer

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Abstract

It is a challenge to synthesize materials that possess the properties of biological muscles—strong, elastic and capable of self-healing. Herein we report a network of poly(dimethylsiloxane) polymer chains crosslinked by coordination complexes that combines high stretchability, high dielectric strength, autonomous self-healing and mechanical actuation. The healing process can take place at a temperature as low as −20 °C and is not significantly affected by surface ageing and moisture. The crosslinking complexes used consist of 2,6-pyridinedicarboxamide ligands that coordinate to Fe(III) centres through three different interactions: a strong pyridyl–iron one, and two weaker carboxamido–iron ones through both the nitrogen and oxygen atoms of the carboxamide groups. As a result, the iron–ligand bonds can readily break and re-form while the iron centres still remain attached to the ligands through the stronger interaction with the pyridyl ring, which enables reversible unfolding and refolding of the chains. We hypothesize that this behaviour supports the high stretchability and self-healing capability of the material.

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Acknowledgements

This work was partially supported by the Major State Basic Research Development Program (Grant No. 2013CB922100 and Grant No. 2011CB808704), Air Force Office of Scientific Research (FA9550-15-1-0106) and Samsung Electronics. F.L. thanks the Swiss National Science Foundation for an Early Mobility Postdoc grant. We thank J. Ma for helpful discussions on the DFT calculations and X. R. Lu, J. C. Lai, X. Y. Jia and J. F. Mei for assistance in the synthesis and characterization of the model complex.

Author information

Author notes

    • Cheng-Hui Li
    •  & Chao Wang

    These authors contributed equally to this work

Affiliations

  1. Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA

    • Cheng-Hui Li
    • , Chao Wang
    • , Franziska Lissel
    •  & Zhenan Bao
  2. State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China

    • Cheng-Hui Li
    • , Jing-Lin Zuo
    • , Peng Zheng
    •  & Xiao-Zeng You
  3. Department of Chemistry, University of California Riverside, Riverside, California 92521, USA

    • Chao Wang
  4. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA

    • Christoph Keplinger
  5. Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA

    • Christoph Keplinger
  6. Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA

    • Christoph Keplinger
  7. Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, USA

    • Lihua Jin
    •  & Christian Linder
  8. National Laboratory of Solid State Microstructure, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China

    • Yang Sun
    •  & Yi Cao

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Contributions

C.-H.L., C.W. and Z.B. conceived, designed and directed the project; C.-H.L., C.W., C.K., Y.S., P.Z., Y.C. and F.L. performed the experiments; C.-H.L., C.W., C.K., Y.S., P.Z., Y.C., F.L., J.-L.Z, X.-Z.Y., L.J., C.L. and Z.B. analysed the data; C.-H.L., C.W. and Z.B. wrote the paper. All the authors discussed the results and commented on the manuscript.

Competing interests

Stanford University has filed a provisional application for a patent based on this technology that names C.H.L., C.W. and Z.B. as inventors.

Corresponding author

Correspondence to Zhenan Bao.

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