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Completely recyclable biopolymers with linear and cyclic topologies via ring-opening polymerization of γ-butyrolactone


Ring-opening polymerization (ROP) is a powerful synthetic methodology for the chemical synthesis of technologically important biodegradable aliphatic polyesters from cyclic esters or lactones. However, the bioderived five-membered γ-butyrolactone (γ-BL) is commonly referred as ‘non-polymerizable’ because of its low strain energy. The chemical synthesis of poly(γ-butyrolactone) (PγBL) through the ROP process has been realized only under ultrahigh pressure (20,000 atm, 160 °C) and only produces oligomers. Here we report that the ROP of γ-BL can, with a suitable catalyst, proceed smoothly to high conversions (90%) under ambient pressure to produce PγBL materials with a number-average molecular weight up to 30 kg mol–1 and with controlled linear and/or cyclic topologies. Remarkably, both linear and cyclic PγBLs can be recycled back into the monomer in quantitative yield by simply heating the bulk materials at 220 °C (linear polymer) or 300 °C (cyclic polymer) for one hour, which thereby demonstrates the complete recyclability of PγBL.

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Figure 1: Proposed mechanism and employed catalysts for the ROP of γ-BL.
Figure 2: MALDI-TOF mass spectra of PγBLs.
Figure 3: PγBLs with different topologies.
Figure 4: Thermodynamics of the γ-BL polymerization.
Figure 5: PγBL topology, thermal stability, intrinsic viscosity and dynamic mechanical behaviour.
Figure 6: Thermal recyclability of linear and cyclic PγBL.


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This work was supported by the National Science Foundation (NSF-1300267).

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M.H. and E.Y.-X.C. conceived the idea and designed the experiments. M.H. performed the experiments. M.H. and E.Y.C. co-wrote the manuscript and participated in data analyses and discussions. E.Y.-X.C. directed the project.

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Correspondence to Eugene Y.-X. Chen.

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The authors declare no competing financial interests.

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Hong, M., Chen, EX. Completely recyclable biopolymers with linear and cyclic topologies via ring-opening polymerization of γ-butyrolactone. Nature Chem 8, 42–49 (2016).

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