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Chemical upcycling of commodity thermoset polyurethane foams towards high-performance 3D photo-printing resins

Nature Chemistry volume 15, pages 1773–1779 (2023)Cite this article

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Abstract

Polyurethane thermosets are indispensable to modern life, but their widespread use has become an increasingly pressing environmental burden. Current recycling approaches are economically unattractive and/or lead to recycled products of inferior properties, making their large-scale implementation unviable. Here we report a highly efficient chemical strategy for upcycling thermoset polyurethane foams that yields products of much higher economic values than the original material. Starting from a commodity foam, we show that the polyurethane network is chemically fragmented into a dissolvable mixture under mild conditions. We demonstrate that three-dimensional photo-printable resins with tunable material mechanical properties—which are superior to commercial high-performance counterparts—can be formulated with the addition of various network reforming additives. Our direct upcycling of commodity foams is economically attractive and can be implemented with ease, and the principle can be expanded to other commodity thermosets.

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Fig. 1: The chemical fragmentation and upcycling mechanism of commodity PUF.
Fig. 2: Upcycling towards reconfigurable tough elastomer.
Fig. 3: Upcycling towards digital light 3D printing.
Fig. 4: Upcycling with recyclable TMG and batch-to-batch consistency.

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Data availability

The data used in this paper are available as Supplementary Data 1 and are also available via Figshare (https://doi.org/10.6084/m9.figshare.23244287). Source data are provided with this paper.

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Acknowledgements

This work is funded by National Natural Science Foundation of China (no. 52033009 to T.X. and no. 52103292 to Z.F.) and China Postdoctoral Science Foundation (no. 2021M692761 to Z.L.). The authors thank S. Jie and J. He for their assistance in performing gel permeation chromatography and FTIR analysis at the State Key Laboratory of Chemical Engineering (Zhejiang University).

Author information

Author notes

  1. These authors contributed equally: Zenghe Liu, Zizheng Fang, Ning Zheng.

Authors and Affiliations

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

    Zenghe Liu, Zizheng Fang, Ning Zheng, Kexuan Yang, Zhuo Sun, Sujing Li, Wei Li & Tao Xie

  2. ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China

    Zenghe Liu & Zizheng Fang

  3. Ningbo Research Institute, Zhejiang University, Ningbo, China

    Zhuo Sun & Jingjun Wu

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  1. Zenghe Liu
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Contributions

T.X. conceived the concept, directed the project and wrote the manuscript. Z.L., Z.F. and N.Z. designed and performed the experiments, with assistance from J.W., and Z.S. K.Y., S.L. and W.L. conducted the life cycle assessment. All authors participated in result analysis and discussion.

Corresponding author

Correspondence to Tao Xie.

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Competing interests

A patent application (ZL202110660721.5) has been granted for Zhejiang University. The inventors are T.X., N.Z., Z.L., Z.F. and Q. Zhao. This patent covers the general concept of chemical upcycling of polyurethane foam including the approach reported in this paper. The remaining authors declare no competing interests.

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Nature Chemistry thanks Haritz Sardon and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Swelling kinetics of PUF.

In the absence of TBD, the PUF reaches swelling equilibria at 25 °C and 120 °C, which proves that it does not dissolve in DMF.

Source data

Extended Data Fig. 2 Stress-strain curves of the compression molded PUF film, the first, and the second regenerated elastomers.

The first regenerated elastomer possesses a superior mechanical property than the compression molded PUF film, and can be further made into a new mechanically different material by another round of recycling.

Source data

Extended Data Fig. 3 Stress-strain curves of the compression molded PUF film, the first, and the second regenerated 3D printed materials.

The first regenerated 3D printed material possesses a superior mechanical property than the compression molded PUF film, and can be further made into a new mechanically different material by another round of recycling.

Source data

Supplementary information

Supplementary Information

Supplementary Figs. 1–29 and Tables 1–6.

Supplementary Video 1

Chemical fragmentation of PUF.

Supplementary Data 1

All raw data for supplementary figures.

Source data

Source Data Fig. 2

Source data for Fig. 2b.

Source Data Fig. 3

Source data for Fig. 3c–e.

Source Data Fig. 4

Source data for Fig. 4.

Source Data Extended Data Fig. 1

Source data for Extended Data Fig. 1.

Source Data Extended Data Fig. 2

Source data for Extended Data Fig. 2.

Source Data Extended Data Fig. 3

Source data for Extended Data Fig. 3.

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Liu, Z., Fang, Z., Zheng, N. et al. Chemical upcycling of commodity thermoset polyurethane foams towards high-performance 3D photo-printing resins. Nat. Chem. 15, 1773–1779 (2023). https://doi.org/10.1038/s41557-023-01308-9

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