Cyclic polymers are topologically interesting and envisioned as a lubricant material. However, scalable synthesis of pure cyclic polymers remains elusive. The most straightforward way is to recover a used catalyst after the synthesis of cyclic polymers and reuse it. Unfortunately, this is demanding because of the catalyst’s vulnerability and inseparability from polymers, which reduce the practicality of the process. Here we develop a continuous circular process, where polymerization, polymer separation and catalyst recovery happen in situ, to dispense a pure cyclic polymer after bulk ring-expansion metathesis polymerization of cyclopentene. It is enabled by introducing silica-supported ruthenium catalysts and newly designed glassware. Different depolymerization kinetics of the cyclic polymer from its linear analogue are also discussed. This process minimizes manual labour, maximizes the security of vulnerable catalysts and guarantees the purity of cyclic polymers, thereby showcasing a prototype of a scalable access to cyclic polymers with increased turnovers (≥415,000) of precious catalysts.
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R. H. Grubbs passed away on 19th December 2021 and was a corresponding author when the article was first submitted. This work is financially supported by the National Science Foundation (CHE#1807154) and the Creative Research Initiative Grant. N. Hart at Caltech Glass Shop is gratefully acknowledged for the glass blowing. S. Hwang at Caltech Solid State NMR Facility is thanked for the solid-state NMR. We thank NCIRF at Seoul National University for supporting headspace gas chromatography–mass spectrometry experiments. Y. Xu (Peking University), J. H. Ko (Caltech), J.-A. Song (Samsung), Y.-J. Jang (University of Minnesota) and D. Allen (Materia) are acknowledged for helpful discussions.
The authors declare no competing interests.
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Yoon, KY., Noh, J., Gan, Q. et al. Scalable and continuous access to pure cyclic polymers enabled by ‘quarantined’ heterogeneous catalysts. Nat. Chem. 14, 1242–1248 (2022). https://doi.org/10.1038/s41557-022-01034-8