A promising solution to address the challenges in plastics sustainability is to replace current polymers with chemically recyclable ones that can depolymerize into their constituent monomers to enable the circular use of materials. Despite some progress, few depolymerizable polymers exhibit the desirable thermal stability and strong mechanical properties of traditional polymers. Here we report a series of chemically recyclable polymers that show excellent thermal stability (decomposition temperature >370 °C) and tunable mechanical properties. The polymers are formed through ring-opening metathesis polymerization of cyclooctene with a trans-cyclobutane installed at the 5 and 6 positions. The additional ring converts the non-depolymerizable polycyclooctene into a depolymerizable polymer by reducing the ring strain energy in the monomer (from 8.2 kcal mol–1 in unsubstituted cyclooctene to 4.9 kcal mol–1 in the fused ring). The fused-ring monomer enables a broad scope of functionalities to be incorporated, providing access to chemically recyclable elastomers and plastics that show promise as next-generation sustainable materials.
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Crystallographic data for the structures in this Article have been deposited at the Cambridge Crystallographic Data Centre (CCDC) under deposition nos 2032007 (2), 2032008 (6) and 2032009 (10). Copies of data can be obtained free of charge from www.ccdc.cam.ac.uk/structures/. All other data supporting the findings of this study are available within the Article and its Supplementary Information. Source data are provided with this paper.
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This work is supported by the University of Akron. The computational resources were provided by Extreme Science and Engineering Discovery Environment (TG-CHE190099). The single-crystal structures were characterized with an X-ray diffractometer supported by the National Science Foundation (CHE-0840446 to C.J.Z.). We thank S. Wang for helpful discussion and K. Williams-Pavlantos and C. Wesdemiotis for conducting the MS analysis.
The authors declare no competing interests.
Peer review information Nature Chemistry thanks Frank Leibfarth and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Materials and instrumentation, synthesis, details for polymerization and depolymerization, Supplementary Figs. 1–103, Supplementary Tables 1–5.
CIF file for 2; (CCDC reference: 2032007).
CIF file for 6; (CCDC reference: 2032008).
CIF file for 10; (CCDC reference: 2032009).
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Sathe, D., Zhou, J., Chen, H. et al. Olefin metathesis-based chemically recyclable polymers enabled by fused-ring monomers. Nat. Chem. 13, 743–750 (2021). https://doi.org/10.1038/s41557-021-00748-5