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The role of polymer mechanochemistry in responsive materials and additive manufacturing

Nature Reviews Materials volume 6, pages 84–98 (2021)Cite this article

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Abstract

The use of mechanical forces to chemically transform polymers dates back decades. In recent years, the use of mechanochemistry to direct constructive transformations in polymers has resulted in a range of engineered molecular responses that span optical, mechanical, electronic and thermal properties. The chemistry that has been developed is now well positioned for use in materials science, polymer physics, mechanics and additive manufacturing. Here, we review the historical backdrop of polymer mechanochemistry, give an overview of the existing toolbox of mechanophores and associated theoretical methods, and speculate as to emerging opportunities in materials science for which current capabilities are seemingly well suited. Non-linear mechanical responses and internal, amplifying stimulus–response feedback loops, including those enabled by, or coupled to, microstructured metamaterial architectures, are seen as particularly promising.

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Fig. 1: Examples of mechanochromism in polymeric materials.
Fig. 2: Representative molecular mechanisms for mechanochromism.
Fig. 3: Visualizing mechanochemical reactions with single-molecule force spectroscopy.
Fig. 4: Stress-induced crosslinking in polymer solutions and polymer networks triggered by mechanophore activation.
Fig. 5: Mechanically triggered transition from insulating to semiconducting properties in materials by the unzipping of a poly(ladderene) mechanophore.
Fig. 6: Examples of mechanophores that release small molecules.
Fig. 7: Structured objects that show a mechanochemical response.

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Acknowledgements

This effort was supported by the US Army Research Laboratory and the Army Research Office under grant W911NF-17-1-0595 to N.B., A.J.B., S.L.C., A.N. and D.W.S. A.J.B. gratefully acknowledges support from the Yamamoto family.

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Authors and Affiliations

  1. Department of Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA, USA

    Maroun Abi Ghanem, Reza Behrou & Nicholas Boechler

  2. Department of Chemistry, University of Washington, Seattle, WA, USA

    Amrita Basu & Alshakim Nelson

  3. Department of Chemistry, University of Wisconsin–Madison, Madison, WI, USA

    Andrew J. Boydston, Brock E. Lynde & Hang Shen

  4. Department of Chemistry, Duke University, Durham, NC, USA

    Stephen L. Craig & Yangju Lin

  5. Department of Mechanical Engineering, University of Washington, Seattle, WA, USA

    Duane W. Storti

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  1. Maroun Abi Ghanem
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Contributions

N.B., A.J.B., S.L.C., A.N. and D.W.S. made substantial contributions to discussion of content, writing and editing of the manuscript. M.A.G., A.B., R.B., Y.L., B.E.L. and H.S. made substantial contributions to the writing.

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Correspondence to Nicholas Boechler, Andrew J. Boydston, Stephen L. Craig, Alshakim Nelson or Duane W. Storti.

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Ghanem, M.A., Basu, A., Behrou, R. et al. The role of polymer mechanochemistry in responsive materials and additive manufacturing. Nat Rev Mater 6, 84–98 (2021). https://doi.org/10.1038/s41578-020-00249-w

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