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Mechanically triggered heterolytic unzipping of a low-ceiling-temperature polymer

Abstract

Biological systems rely on recyclable materials resources such as amino acids, carbohydrates and nucleic acids. When biomaterials are damaged as a result of aging or stress, tissues undergo repair by a depolymerization–repolymerization sequence of remodelling. Integration of this concept into synthetic materials systems may lead to devices with extended lifetimes. Here, we show that a metastable polymer, end-capped poly(o-phthalaldehyde), undergoes mechanically initiated depolymerization to revert the material to monomers. Trapping experiments and steered molecular dynamics simulations are consistent with a heterolytic scission mechanism. The obtained monomer was repolymerized by a chemical initiator, effectively completing a depolymerization–repolymerization cycle. By emulating remodelling of biomaterials, this model system suggests the possibility of smart materials where aging or mechanical damage triggers depolymerization, and orthogonal conditions regenerate the polymer when and where necessary.

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Figure 1: GPC studies of sonicated polymers.
Figure 2: Mechanistic studies by ab initio steered molecular dynamics calculations
Figure 3: GPC data for linear trapping experiments with increasing sonication time.
Figure 4: Depolymerization–repolymerization of PPA in THF.

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Acknowledgements

This material is based on work supported by the Air Force Office of Scientific Research Discovery Program (grant no. 392 AF FA9550-10-1-0255), the National Science Foundation (CHE-1300313), the US Army Research Laboratory, the US Army Research Office (grant no. W911NF-07-1-0409) and the Department of Defense (Office of the Assistant Secretary of Defense for Research and Engineering) through an NSSEFF fellowship. J.A.K. acknowledges the Springborn Endowment for a graduate fellowship and funding for materials as part of the Center for Electrical Energy Storage, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (award no. DOE ANL 9F-31921J). G.I.P. and A.J.B. acknowledge support from the University of Washington, University of Washington Royalty Research Fund, and US Army Research Office Young Investigator Program (grant no. W911NF-11-1-0289). H.J.K. holds a Career Award at the Scientific Interface from the Burroughs Wellcome Fund.

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J.S.M., T.J.M., A.J.B. and S.R.W. directed the research. J.S.M., A.J.B., C.E.D. and P.A.M. conceived the idea. C.E.D., G.I.P., J.A.K. and P.A.M. performed the experiments. H.J.K. and B.D.M. conducted the theoretical studies. All authors participated in writing the manuscript.

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Correspondence to Jeffrey S. Moore.

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Diesendruck, C., Peterson, G., Kulik, H. et al. Mechanically triggered heterolytic unzipping of a low-ceiling-temperature polymer. Nature Chem 6, 623–628 (2014). https://doi.org/10.1038/nchem.1938

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