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Reprocessable and ultratough epoxy thermosetting plastic

Nature Sustainability (2024)Cite this article

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Abstract

Due to their exceptional manufacturability and excellent mechanical properties, epoxy thermosets are one of the most widely used plastics, finding many industrial applications. However, the crosslinked polymer network renders them inherently brittle and not recyclable, raising sustainability concerns. Here we show epoxy thermosets with combined high toughness and reprocessability by innovating the chemistry of curing, a crosslinking process in polymers. Specifically, taking advantage of a one-pot epoxy curing mechanism with a boronic-ester-containing aromatic diamine crosslinker and an aliphatic monoamine, the stepwise reaction of the amines affords unique nanoscale phase separation. As a result, the epoxy thermoset exhibits maximum elongation of 375% and tensile toughness of 108.4 MJ m−3, more than one order of magnitude higher than that of the conventional counterparts. Moreover, the introduced dynamic boronic ester bonds endow the thermoset with unusual reprocessability for extended service life, while other properties are not compromised notably after four cycles. The feasibility to simultaneously overcome the two major bottlenecks for epoxy thermosets opens opportunities to recycle and reinvent other industrially relevant plastics.

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Fig. 1: Synthesis and mechanical properties of the epoxy thermoset.
Fig. 2: Thermal and mechanical properties of the epoxy thermosets.
Fig. 3: Microstructural characterization and toughening mechanism of EP-25.
Fig. 4: Reprocessing performance of EP-25.

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Data availability

All data that support the findings of this study are available as Source data Figs. 1–4 and Supplementary_data_set. They are also available via Figshare (https://doi.org/10.6084/m9.figshare.25425292). Source data are provided with this paper.

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Acknowledgements

This research was supported by the National Natural Science Foundation of China (grant numbers U23A2098 (T.X.), 52322307 (N.Z.), 22275162 (N.Z.) and 22288102 (T.X.)). We thank N. Zheng, L. Xu, H. Li and S. Shen for their assistance in performing SEM and DMA tests at the State Key Laboratory of Chemical Engineering (Zhejiang University) and L. Chen for performing near-infrared analyses at the State Key Laboratory of Extreme Photonics and Instrumentation (Zhejiang University).

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Author notes

  1. These authors contributed equally: Wenxuan Wu, Haijun Feng.

Authors and Affiliations

  1. State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China

    Wenxuan Wu, Haijun Feng, Lulin Xie, Ning Zheng & Tao Xie

  2. School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, In-situ Center for Physical Science, and Center of Hydrogen Science, Shanghai Jiao Tong University, Shanghai, China

    Anyang Zhang & Feng Liu

  3. College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou, China

    Zenghe Liu

  4. Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China

    Tao Xie

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Contributions

N.Z. and T.X. conceived the idea and supervised the project. W.W. and H.F. conducted the experiments with assistance from L.X. and Z.L. The SAXS data were analysed by A.Z. and F.L. The paper was written by W.W., N.Z. and T.X.

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Correspondence to Ning Zheng or Tao Xie.

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Nature Sustainability thanks Xinli Jing, Jian-Bo Zhu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Materials, SAXS data analysis, Supplementary Tables 1–6, Figs. 1–13 and additional references.

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Supplementary Data Set 1

Source data for Supplementary Figs. 1–13, source figures for TEM and SEM.

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Source Data Fig. 1

Statistical source data.

Source Data Fig. 2

Statistical source data.

Source Data Fig. 3

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Source Data Fig. 4

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Wu, W., Feng, H., Xie, L. et al. Reprocessable and ultratough epoxy thermosetting plastic. Nat Sustain (2024). https://doi.org/10.1038/s41893-024-01331-9

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