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Proton-triggered topological transformation in superbase-mediated selective polymerization enables access to ultrahigh-molar-mass cyclic polymers

Nature Chemistry (2024)Cite this article

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Abstract

The selective synthesis of ultrahigh-molar-mass (UHMM, >2 million Da) cyclic polymers is challenging as an exceptional degree of spatiotemporal control is required to overcome the possible undesired reactions that can compete with the desired intramolecular cyclization. Here we present a counterintuitive synthetic methodology for cyclic polymers, represented here by polythioesters, which proceeds via superbase-mediated ring-opening polymerization of gem-dimethylated thiopropiolactone, followed by macromolecular cyclization triggered by protic quenching. This proton-triggered linear-to-cyclic topological transformation enables selective, linear polymer-like access to desired cyclic polythioesters, including those with UHMM surpassing 2 MDa. In addition, this method eliminates the need for stringent conditions such as high dilution to prevent or suppress linear polymer contaminants and presents the opposite scenario in which protic-free conditions are required to prevent cyclic polymer formation, which is capitalized to produce cyclic polymers on demand. Furthermore, such UHMM cyclic polythioester exhibits not only much enhanced thermostability and mechanical toughness, but it can also be quantitatively recycled back to monomer under mild conditions due to its gem-disubstitution.

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Fig. 1: Proton-triggered cyclization versus in-polymerization cyclization.
Fig. 2: Evidence for the controlled synthesis l- and c-P3T(Me)2P.
Fig. 3: Comparative characterizations of linear (orange lines) and cyclic (purple lines) P3T(Me)2P prepared by different quenching methods.
Fig. 4: Thermal, rheological and mechanical properties of c-P3T(Me)2P.
Fig. 5: Chemical recycling to monomer.

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Full experimental details and the data supporting the findings of this study are available within the article and its Supplementary Information. Source data are provided with this paper.

References

  1. Tezuka, Y. Topological Polymer Chemistry: Progress of Cyclic Polymers in Syntheses, Properties, and Functions (Word Scientific, 2012).

  2. Miao, Z. et al. Cyclic polyacetylene. Nat. Chem. 13, 792–799 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  3. Bielawski, C. W., Benitez, D. & Grubbs, R. H. An ‘endless’ route to cyclic polymers. Science 297, 2041–2044 (2002).

    Article  CAS  PubMed  Google Scholar 

  4. Haque, F. M. & Grayson, S. M. The synthesis, properties and potential applications of cyclic polymers. Nat. Chem. 12, 433–444 (2020).

    Article  CAS  PubMed  Google Scholar 

  5. Laurent, B. A. & Grayson, S. M. An efficient route to well-defined macrocyclic polymers via ‘click’ cyclization. J. Am. Chem. Soc. 128, 4238–4239 (2006).

    Article  CAS  PubMed  Google Scholar 

  6. Sun, P., Chen, J., Liu, J. A., & Zhang, K. Self-accelerating click reaction for cyclic polymer. Macromolecules 50, 1463–1472 (2017).

    Article  CAS  Google Scholar 

  7. Kapnistos, M. et al. Unexpected power-law stress relaxation of entangled ring polymers. Nat. Mater. 7, 997–1002 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Pasquino, R. et al. Viscosity of ring polymer melts. ACS Macro Lett. 2, 874–878 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Doi, Y. et al. Melt rheology of ring polystyrenes with ultrahigh purity. Macromolecules 48, 3140–3147 (2015).

    Article  CAS  Google Scholar 

  10. Gambino, T., Martínez de Ilarduya, A., Alegría, A. & Barroso-Bujans, F. Dielectric relaxations in poly(glycidyl phenyl ether): effects of microstructure and cyclic topology. Macromolecules 49, 1060–1069 (2016).

    Article  CAS  Google Scholar 

  11. Ziebarth, J. D. et al. Comparison of critical adsorption points of ring polymers with linear polymers. Macromolecules 49, 8780–8788 (2016).

    Article  Google Scholar 

  12. Kammiyada, H., Ouchi, M. & Sawamoto, M. A study on physical properties of cyclic poly(vinyl ether)s synthesized via ring-expansion cationic polymerization. Macromolecules 50, 841–848 (2017).

    Article  CAS  Google Scholar 

  13. Chen, B., Jerger, K., Frechet, J. M. & Szoka, F. C. Jr. The influence of polymer topology on pharmacokinetics: differences between cyclic and linear PEGylated poly(acrylic acid) comb polymers. J. Control. Release 140, 203–209 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Nasongkla, N. et al. Dependence of pharmacokinetics and biodistribution on polymer architecture: effect of cyclic versus linear polymers. J. Am. Chem. Soc. 131, 3842–3843 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Yamamoto, T. & Tezuka, Y. Cyclic polymers revealing topology effects upon self-assemblies, dynamics and responses. Soft Matter 11, 7458–7468 (2015).

    Article  CAS  PubMed  Google Scholar 

  16. Arno, M. C. et al. Exploiting topology-directed nanoparticle disassembly for triggered drug delivery. Biomaterials 180, 184–192 (2018).

    Article  CAS  PubMed  Google Scholar 

  17. Natansohn, A. & Rochon, P. Photoinduced motions in azo-containing polymers. Chem. Rev. 102, 4139–4175 (2002).

    Article  CAS  PubMed  Google Scholar 

  18. Xu, X. et al. The first example of main-chain cyclic azobenzene polymers. Macromol. Rapid Commun. 31, 1791–1797 (2010).

    Article  CAS  PubMed  Google Scholar 

  19. Hoskins, J. N. & Grayson, S. M. Synthesis and degradation behavior of cyclic poly(ε-caprolactone). Macromolecules 42, 6406–6413 (2009).

    Article  CAS  Google Scholar 

  20. Williams, R. J., Dove, A. P. & O’Reilly, R. K. Self-assembly of cyclic polymers. Polym. Chem. 6, 2998–3008 (2015).

    Article  CAS  Google Scholar 

  21. Josse, T., De Winter, J., Gerbaux, P. & Coulembier, O. Cyclic polymers by ring-closure strategies. Angew. Chem. Int. Ed. 55, 13944–13958 (2016).

    Article  CAS  Google Scholar 

  22. Chang, Y. A. & Waymouth, R. M. Recent progress on the synthesis of cyclic polymers via ring-expansion strategies. J. Polym. Sci., Part A: Polym. Chem. 55, 2892–2902 (2017).

    Article  CAS  Google Scholar 

  23. Wang, T.-W. & Golder, M. R. Advancing macromolecular hoop construction: recent developments in synthetic cyclic polymer chemistry. Polym. Chem. 12, 958–969 (2021).

    Article  CAS  Google Scholar 

  24. Yoon, K. Y. et al. Scalable and continuous access to pure cyclic polymers enabled by ‘quarantined’ heterogeneous catalysts. Nat. Chem. 14, 1242–1248 (2022).

    Article  CAS  PubMed  Google Scholar 

  25. Boydston, A. J., Xia, Y., Kornfield, J. A., Gorodetskaya, I. A. & Grubbs, R. H. Cyclic ruthenium-alkylidene catalysts for ring-expansion metathesis polymerization. J. Am. Chem. Soc. 130, 12775–12782 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Sarkar, S. et al. An OCO3− trianionic pincer tungsten(VI) alkylidyne: rational design of a highly active alkyne polymerization catalyst. J. Am. Chem. Soc. 134, 4509–4512 (2012).

    Article  CAS  PubMed  Google Scholar 

  27. Gonsales, S. A. et al. Highly tactic cyclic polynorbornene: stereoselective ring expansion metathesis polymerization of norbornene catalyzed by a new tethered tungsten-alkylidene catalyst. J. Am. Chem. Soc. 138, 4996–4999 (2016).

    Article  CAS  PubMed  Google Scholar 

  28. Roland, C. D., Li, H., Abboud, K. A., Wagener, K. B. & Veige, A. S. Cyclic polymers from alkynes. Nat. Chem. 8, 791–796 (2016).

    Article  CAS  PubMed  Google Scholar 

  29. Wang, T. W., Huang, P. R., Chow, J. L., Kaminsky, W. & Golder, M. R. A cyclic ruthenium benzylidene initiator platform enhances reactivity for ring-expansion metathesis polymerization. J. Am. Chem. Soc. 143, 7314–7319 (2021).

    Article  CAS  PubMed  Google Scholar 

  30. McGraw, M. L., Clarke, R. W. & Chen, E. Y.-X. Synchronous control of chain length/sequence/topology for precision synthesis of cyclic block copolymers from monomer mixtures. J. Am. Chem. Soc. 143, 3318–3322 (2021).

    Article  CAS  PubMed  Google Scholar 

  31. McGraw, M. L. et al. Mechanism of spatial and temporal control in precision cyclic vinyl polymer synthesis by Lewis pair polymerization. Angew. Chem. Int. Ed. 61, e202116303 (2022).

    Article  CAS  Google Scholar 

  32. Song, Y., He, J., Zhang, Y., Gilsdorf, R. A. & Chen, E. Y.-X. Recyclable cyclic bio-based acrylic polymer via pairwise monomer enchainment by a trifunctional Lewis pair. Nat. Chem. 15, 366–376 (2023).

    Article  CAS  PubMed  Google Scholar 

  33. Culkin, D. A. et al. Zwitterionic polymerization of lactide to cyclic poly(lactide) by using N-heterocyclic carbene organocatalysts. Angew. Chem. Int. Ed. 46, 2627–2630 (2007).

    Article  CAS  Google Scholar 

  34. Guo, L., Lahasky, S. H., Ghale, K. & Zhang, D. N-heterocyclic carbene-mediated zwitterionic polymerization of N-substituted N-carboxyanhydrides toward poly(alpha-peptoid)s: kinetic, mechanism, and architectural control. J. Am. Chem. Soc. 134, 9163–9171 (2012).

    Article  CAS  PubMed  Google Scholar 

  35. Brown, H. A. & Waymouth, R. M. Zwitterionic ring-opening polymerization for the synthesis of high molecular weight cyclic polymers. Acc. Chem. Res. 46, 2585–2596 (2013).

    Article  CAS  PubMed  Google Scholar 

  36. Piedra-Arroni, E., Ladaviere, C., Amgoune, A. & Bourissou, D. Ring-opening polymerization with Zn(C6F5)2-based Lewis pairs: original and efficient approach to cyclic polyesters. J. Am. Chem. Soc. 135, 13306–13309 (2013).

    Article  CAS  PubMed  Google Scholar 

  37. Reisberg, S. H., Hurley, H. J., Mathers, R. T., Tanski, J. M. & Getzler, Y. D. Y. L. Lactide cyclopolymerization kinetics, X-ray structure, and solution dynamics of (tBu-SalAmEE)Al and a cautionary tale of polymetalate formation. Macromolecules 46, 3273–3279 (2013).

    Article  CAS  Google Scholar 

  38. Asenjo-Sanz, I., Veloso, A., Miranda, J. I., Pomposo, J. A. & Barroso-Bujans, F. Zwitterionic polymerization of glycidyl monomers to cyclic polyethers with B(C6F5)3. Polym. Chem. 5, 6905–6908 (2014).

    Article  CAS  Google Scholar 

  39. Hong, M. & Chen, E. Y.-X. Completely recyclable biopolymers with linear and cyclic topologies via ring-opening polymerization of gamma-butyrolactone. Nat. Chem. 8, 42–49 (2016).

    Article  CAS  PubMed  Google Scholar 

  40. 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).

    Article  CAS  PubMed  Google Scholar 

  41. Naruse, K., Takasu, A. & Higuchi, M. Direct observation of a cyclic vinyl polymer prepared by anionic polymerization using N-heterocyclic carbene and subsequent ring-closure without highly diluted conditions. Macromol. Chem. Phys. 221, 2000004 (2020).

    Article  CAS  Google Scholar 

  42. Li, H., Ollivier, J., Guilaume, S. M. & Carpentier, J.-F. Tacticity control of cyclic poly(3-thiobutyrate) prepared by ring-opening polymerization of racemic β-thiobutyrolactone. Angew. Chem. Int. Ed. 58, 618–623 (2022).

    Google Scholar 

  43. Hong, M. & Chen, E. Y.-X. Chemically recyclable polymers: a circular economy approach to sustainability. Green Chem. 19, 3692–3706 (2017).

    Article  CAS  Google Scholar 

  44. 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).

    Article  CAS  Google Scholar 

  45. Jehanno, C. et al. Critical advances and future opportunities in upcycling commodity polymers. Nature 603, 803–814 (2022).

    Article  CAS  PubMed  Google Scholar 

  46. Abel, B. A., Snyder, R. L. & Coates, G. W. Chemically recyclable thermoplastics from reversible-deactivation polymerization of cyclic acetals. Science 373, 783–789 (2021).

    Article  CAS  PubMed  Google Scholar 

  47. Haussler, M., Eck, M., Rothauer, D. & Mecking, S. Closed-loop recycling of polyethylene-like materials. Nature 590, 423–427 (2021).

    Article  PubMed  Google Scholar 

  48. Jung, M. E. & Piizzi, G. gem-Disubstituent effect: theoretical basis and synthetic applications. Chem. Rev. 105, 1735–1766 (2005).

    Article  CAS  PubMed  Google Scholar 

  49. Zhou, L. et al. Chemically circular, mechanically tough and melt-processable polyhydroxyalkanoates. Science 380, 64–69 (2023).

    Article  CAS  PubMed  Google Scholar 

  50. Xiong, W. et al. Geminal dimethyl substitution enables controlled polymerization of penicillamine-derived β-thiolactones and reversed depolymerization. Chem. 6, 1831–1843 (2020).

    Article  CAS  Google Scholar 

  51. Stellmach, K. A. et al. Modulating polymerization thermodynamics of thiolactones through substituent and heteroatom incorporation. ACS Macro Lett. 11, 895–901 (2022).

    Article  CAS  PubMed  Google Scholar 

  52. Li, X. L., Clarke, R. W., Jiang, J. Y., Xu, T. Q. & Chen, E. Y.-X. A circular polyester platform based on simple gem-disubstituted valerolactones. Nat. Chem. 15, 278–285 (2023).

    Article  CAS  PubMed  Google Scholar 

  53. Vazdar, K. et al. Design of novel uncharged organic superbases: merging basicity and functionality. Acc. Chem. Res. 54, 3108–3123 (2021).

    Article  CAS  PubMed  Google Scholar 

  54. Schmitt, M., Faliveve, L., Caporaso, L., Cavallo, L. & Chen, E. Y.-X. High-speed organocatalytic polymerization of a renewable methylene butyrolactone by a phosphazene superbase. Polym. Chem. 5, 3261–3270 (2014).

    Article  CAS  Google Scholar 

  55. Sweeny, W. & Casey, D. J. Propiothiolactone polymers. US patent 3,367,921A (1965).

  56. Kumaki, J., Nishikawa, Y. & Hashimoto, T. Visualization of single-chain conformations of a synthetic polymer with atomic force microscopy. J. Am. Chem. Soc. 118, 3321–3322 (1996).

    Article  CAS  Google Scholar 

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Acknowledgements

Funding was provided by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Materials and Manufacturing Technologies Office (AMMTO) and Bioenergy Technologies Office (BETO). This work was performed as part of the Bio-Optimized Technologies to keep Thermoplastics out of Landfills and the Environment (BOTTLE) Consortium and was supported by AMMTO and BETO under Contract DE-AC36-08GO28308 with the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC. The BOTTLE Consortium includes members from Colorado State University. The work by L.T.R. and E.Y.-X.C. was supported by the US National Science Foundation (grant no. NSF-2305058). We thank R. R. Gowda for dn/dc measurements.

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  1. Department of Chemistry, Colorado State University, Fort Collins, CO, USA

    Li Zhou, Liam T. Reilly, Changxia Shi, Ethan C. Quinn & Eugene Y.-X. Chen

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Contributions

E.Y.-X.C. conceived the project and directed the research. L.Z., L.T.R., C.S. and E.C.Q. designed and conducted experiments and analysed the results. L.Z. wrote the initial paper, L.T.R. and E.C.Q. contributed to subsequent versions. E.Y.-X.C. edited the initial and subsequent versions and reviewed the entire paper.

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Correspondence to Eugene Y.-X. Chen.

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E.Y.-X.C. and L.Z. are named inventors on a pending PCT/US patent application (2023/021512) submitted by Colorado State University, which covers chemically circular polymers. The other authors declare no competing interests.

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Nature Chemistry thanks Matthew Golder, Sophie Guillaume, Julia Pribyl Ham and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Zhou, L., Reilly, L.T., Shi, C. et al. Proton-triggered topological transformation in superbase-mediated selective polymerization enables access to ultrahigh-molar-mass cyclic polymers. Nat. Chem. (2024). https://doi.org/10.1038/s41557-024-01511-2

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