Mechanically Robust Supramolecular Plastics with Energy-Saving and Highly Efficient Closed-Loop Recyclability

Conventional plastics are usually incinerated or dumped in landfills and oceans after usage, leading to a considerable waste of resources and severe environmental pollution. Closed-loop recycling of plastics in an energy-saving and easy-to-conduct way remains an ongoing challenge. Herein, closed-loop recyclable supramolecular plastics with high mechanical robustness and excellent thermal stability are fabricated via dynamically cross-linking phenylboronic acid-terminated poly(aryl ether ketone) oligomers and small organic molecules with boroxines, denoted as PAEK-CB. Depending on the feed molar ratio of the monomers, the PAEK-CB plastics can exhibit a tensile strength of ∼46.7 MPa and a Young's modulus of ∼1.21 GPa. Owing to the dynamic nature of boroxines, the PAEK-CB plastics can be depolymerized in the N-methylpyrrolidone/ethanol mixture solvent. Thus, the monomers can be easily and efficiently recovered on their solubility difference in ethanol. The recovered monomers with high purity and isolated yields (>90% during the five recycling processes) can be used to remanufacture the PAEK-CB plastics without losing their original mechanical performance during five polymer–monomer–polymer cycles. The mild recycling condition allows for the selective recovery of the PAEK-CB plastic from daily produced plastic waste streams, meaning a further step toward developing closed-loop recycling plastic in the future.