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.
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
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.
Rochman, C. M. et al. Classify plastic waste as hazardous. Nature 494, 169–171 (2013).
The New Plastics Economy: Rethinking the Future of Plastics and Catalysing Action (Ellen MacArthur Foundation, 2017).
Haider, T. P., Völker, C., Kramm, J., Landfester, K. & Wurm, F. R. Plastics of the future? The impact of biodegradable polymers on the environment and on society. Angew. Chem. Int. Ed. 58, 50–62 (2019).
Ignatyev, I. A., Thielemans, W. & Vander Beke, B. Recycling of polymers: a review. ChemSusChem 7, 1579–1593 (2014).
Tang, X. & Chen, E. Y. X. Toward infinitely recyclable plastics derived from renewable cyclic esters. Chem 5, 284–312 (2019).
Coates, G. W. & Getzler, Y. D. Y. L. Chemical recycling to monomer for an ideal, circular polymer economy. Nat. Rev. Mater. 5, 501–516 (2020).
Snow, R. D. & Frey, F. E. The reaction of sulfur dioxide with olefins: the ceiling temperature phenomenon. J. Am. Chem. Soc. 65, 2417–2418 (1943).
Dainton, F. S. & Ivin, K. J. Reversibility of the propagation reaction in polymerization processes and its manifestation in the phenomenon of a ‘ceiling temperature’. Nature 162, 705–707 (1948).
McCormick, H. W. Ceiling temperature of α-methylstyrene. J. Polym. Sci. 25, 488–490 (1957).
North, A. M. & Richardson, D. Entropy of stereoregularity in aldehyde polymerization. Polymer 6, 333–338 (1965).
Park, C. W. et al. Thermally triggered degradation of transient electronic devices. Adv. Mater. 27, 3783–3788 (2015).
Feinberg, A. M. et al. Cyclic poly(phthalaldehyde): thermoforming a bulk transient material. ACS Macro Lett. 7, 47–52 (2018).
Tran, H. et al. Stretchable and fully degradable semiconductors for transient electronics. ACS Cent. Sci. 5, 1884–1891 (2019).
Zhu, J.-B., Watson, E. M., Tang, J. & Chen, E. Y. X. A synthetic polymer system with repeatable chemical recyclability. Science 360, 398–403 (2018).
Grubbs, R. H. Olefin metathesis. Tetrahedron 60, 7117–7140 (2004).
Grubbs, R. H. & Khosravi, E. Handbook of Metathesis: Polymer Synthesis 2nd edn, Vol. 3 (Wiley, 2015).
Monfette, S. & Fogg, D. E. Equilibrium ring-closing metathesis. Chem. Rev. 109, 3783–3816 (2009).
Neary, W. J. & Kennemur, J. G. Polypentenamer renaissance: challenges and opportunities. ACS Macro Lett. 8, 46–56 (2019).
Myers, S. B. & Register, R. A. Synthesis of narrow-distribution polycyclopentene using a ruthenium ring-opening metathesis initiator. Polymer 49, 877–882 (2008).
Neary, W. J. & Kennemur, J. G. Variable temperature ROMP: leveraging low ring strain thermodynamics to achieve well-defined polypentenamers. Macromolecules 50, 4935–4941 (2017).
Schleyer, P. v. R., Williams, J. E. & Blanchard, K. R. Evaluation of strain in hydrocarbons. The strain in adamantane and its origin. J. Am. Chem. Soc. 92, 2377–2386 (1970).
Hejl, A., Scherman, O. A. & Grubbs, R. H. Ring-opening metathesis polymerization of functionalized low-strain monomers with ruthenium-based catalysts. Macromolecules 38, 7214–7218 (2005).
Martinez, H., Ren, N., Matta, M. E. & Hillmyer, M. A. Ring-opening metathesis polymerization of 8-membered cyclic olefins. Polym. Chem. 5, 3507–3532 (2014).
Walker, R., Conrad, R. M. & Grubbs, R. H. The living ROMP of trans-cyclooctene. Macromolecules 42, 599–605 (2009).
You, W., Padgett, E., MacMillan, S. N., Muller, D. A. & Coates, G. W. Highly conductive and chemically stable alkaline anion exchange membranes via ROMP of trans-cyclooctene derivatives. Proc. Natl Acad. Sci. USA 116, 9729–9734 (2019).
You, W., Hugar, K. M. & Coates, G. W. Synthesis of alkaline anion exchange membranes with chemically stable imidazolium cations: unexpected cross-linked macrocycles from ring-fused ROMP monomers. Macromolecules 51, 3212–3218 (2018).
Scherman, O. A., Walker, R. & Grubbs, R. H. Synthesis and characterization of stereoregular ethylene-vinyl alcohol copolymers made by ring-opening metathesis polymerization. Macromolecules 38, 9009–9014 (2005).
Hsu, T.-G. et al. A polymer with “locked” degradability: superior backbone stability and accessible degradability enabled by mechanophore installation. J. Am. Chem. Soc. 142, 2100–2104 (2020).
Asaoka, S., Horiguchi, H., Wada, T. & Inoue, Y. Enantiodifferentiating photocyclodimerization of cyclohexene sensitized by chiral benzenecarboxylates. J. Chem. Soc. Perkin Trans. 2, 737–747 (2000).
Maeda, H. et al. Synthesis and photochemical properties of stilbenophanes tethered by silyl chains. Control of (2π + 2π) photocycloaddition, cis−trans photoisomerization, and photocyclization. J. Org. Chem. 70, 9693–9701 (2005).
Xu, Y., Smith, M. D., Krause, J. A. & Shimizu, L. S. Control of the intramolecular [2+2] photocycloaddition in a bis-stilbene macrocycle. J. Org. Chem. 74, 4874–4877 (2009).
Poplata, S., Tröster, A., Zou, Y.-Q. & Bach, T. Recent advances in the synthesis of cyclobutanes by olefin [2 + 2] photocycloaddition reactions. Chem. Rev. 116, 9748–9815 (2016).
Feist, J. D. & Xia, Y. Enol ethers are effective monomers for ring-opening metathesis polymerization: synthesis of degradable and depolymerizable poly(2,3-dihydrofuran). J. Am. Chem. Soc. 142, 1186–1189 (2020).
Royzen, M., Yap, G. P. A. & Fox, J. M. A photochemical synthesis of functionalized trans-cyclooctenes driven by metal complexation. J. Am. Chem. Soc. 130, 3760–3761 (2008).
Neary, W. J., Isais, T. A. & Kennemur, J. G. Depolymerization of bottlebrush polypentenamers and their macromolecular metamorphosis. J. Am. Chem. Soc. 141, 14220–14229 (2019).
Badamshina, E. R. et al. Investigation of the mechanism of polypentenamer degradation in the presence of metathesis catalysts. Polym. Sci. USSR 24, 164–170 (1982).
Prelog, V. Conformation and reactivity of medium-sized ring compounds. Pure Appl. Chem. 6, 545–560 (1963).
Burevschi, E., Peña, I. & Sanz, M. E. Medium-sized rings: conformational preferences in cyclooctanone driven by transannular repulsive interactions. Phys. Chem. Chem. Phys. 21, 4331–4338 (2019).
Liu, H. et al. Dynamic remodeling of covalent networks via ring-opening metathesis polymerization. ACS Macro Lett. 7, 933–937 (2018).
Stalpaert, M. et al. Olefins from biobased sugar alcohols via selective, ru-mediated reaction in catalytic phosphonium ionic liquids. ACS Catal. 10, 9401–9409 (2020).
Sutthasupa, S., Shiotsuki, M. & Sanda, F. Recent advances in ring-opening metathesis polymerization, and application to synthesis of functional materials. Polym. J. 42, 905–915 (2010).
Caruso, M. M. et al. Mechanically-induced chemical changes in polymeric materials. Chem. Rev. 109, 5755–5798 (2009).
Feringa, B. L. The art of building small: from molecular switches to motors (Nobel Lecture). Angew. Chem. Int. Ed. 56, 11060–11078 (2017).
Walczak, M. A. A., Krainz, T. & Wipf, P. Ring-strain-enabled reaction discovery: new heterocycles from bicyclo[1.1.0]butanes. Acc. Chem. Res. 48, 1149–1158 (2015).
Agard, N. J., Prescher, J. A. & Bertozzi, C. R. A strain-promoted [3 + 2] azide−alkyne cycloaddition for covalent modification of biomolecules in living systems. J. Am. Chem. Soc. 126, 15046–15047 (2004).
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.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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).
About this article
Cite this article
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