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Nanostructured block copolymer muscles

Nature Nanotechnology volume 17, pages 752–758 (2022)Cite this article

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Abstract

High-performance actuating materials are necessary for advances in robotics, prosthetics and smart clothing. Here we report a class of fibre actuators that combine solution-phase block copolymer self-assembly and strain-programmed crystallization. The actuators consist of highly aligned nanoscale structures with alternating crystalline and amorphous domains, resembling the ordered and striated pattern of mammalian skeletal muscle. The reported nanostructured block copolymer muscles excel in several aspects compared with current actuators, including efficiency (75.5%), actuation strain (80%) and mechanical properties (for example, strain-at-break of up to 900% and toughness of up to 121.2 MJ m−3). The fibres exhibit on/off rotary actuation with a peak rotational speed of 450 r.p.m. Furthermore, the reported fibres demonstrate multi-trigger actuation (heat and hydration), offering switchable mechanical properties and various operating modes. The versatility and recyclability of the polymer fibres, combined with the facile fabrication method, opens new avenues for creating multifunctional and recyclable actuators using block copolymers.

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Fig. 1: Fibre fabrication through SPC of hydrogels created from self-assembled ABA triblock copolymers.
Fig. 2: SAXS and WAXS characterizations of strain-processed fibres indicate that the structure is highly aligned and consists of alternating crystalline and amorphous domains.
Fig. 3: Strained fibres exhibit exceptional mechanical and actuation properties.
Fig. 4: Reversible and rotational actuation properties of strained fibres.

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Data availability

The datasets that support the finding of this study are available in ScholarSphere repository with the identifier(s) https://doi.org/10.26207/tvbb-rf14. Source data are provided with this paper.

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Acknowledgements

This work was supported by the Air Force Office of Scientific Research under the Young Investigator Prize (award 18RT0680, R.J.H.), the National Science Foundation through the DMREF programme (CMMI 2119717, R.J.H.) and the Materials Research Institute seed grant from The Pennsylvania State University (R.J.H.). M.K. was supported by National Science Foundation grant CBET 1946392 and DMREF programme CMMI 1627197. V.G. was supported in part by the Welch Foundation (grant F-1599). This research used the Complex Materials Scattering beamline of the National Synchrotron Light Source II, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract number DE-SC0012704. TEM, SEM, SAXS and WAXS measurements were taken at the Materials Characterization Lab (MCL) in the Materials Research Institute (MRI) at The Pennsylvania State University.

Author information

Authors and Affiliations

  1. South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou, China

    Chao Lang

  2. Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA

    Chao Lang, Elisabeth C. Lloyd, Kelly E. Matuszewski, Yifan Xu & Robert J. Hickey

  3. Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou, China

    Chao Lang

  4. McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA

    Venkat Ganesan & Manish Kumar

  5. Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX, USA

    Rui Huang

  6. Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX, USA

    Manish Kumar

  7. Materials Research Institute, The Pennsylvania State University, University Park, PA, USA

    Robert J. Hickey

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Contributions

C.L., M.K. and R.J.H. conceived the research. C.L. developed, prepared and characterized materials. C.L. measured mechanical and actuation properties. E.C.L. and Y.X. conducted X-ray measurements. C.L. and K.E.M. analysed actuation properties using video analysis. V.G. and R.H. developed the mechanical property model. C.L., M.K. and R.J.H. wrote the manuscript. R.J.H. supervised the research. All authors read and commented on the manuscript.

Corresponding author

Correspondence to Robert J. Hickey.

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The authors declare no competing interests.

Peer review

Peer review information

Nature Nanotechnology thanks Xuanhe Zhao and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–22 and Tables 1–5.

Supplementary Video 1

Linear actuation by heating.

Supplementary Video 2

Linear actuation by hydration.

Supplementary Video 3

An umbrella that automatically opens when applying water.

Supplementary Video 4

Rotational actuation by hydration.

Supplementary Video 5

Rotational actuation by heating.

Source data

Source Data Fig. 1

Source data for Fig. 1d

Source Data Fig. 2

Source data for Figs. 2e–g, k

Source Data Fig. 3

Source data for Figs. 3a–f

Source Data Fig. 4

Source data for Figs. 4a–c,f

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Lang, C., Lloyd, E.C., Matuszewski, K.E. et al. Nanostructured block copolymer muscles. Nat. Nanotechnol. 17, 752–758 (2022). https://doi.org/10.1038/s41565-022-01133-0

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