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 considerablewaste of resources and severe environmental pollution. Closed-looprecycling of plastics in an energy-saving and easy-to-conduct wayremains an ongoing challenge. Herein, closed-loop recyclablesupramolecular plastics with high mechanical robustness and excellentthermal stability are fabricated via dynamically cross-linking phenyl-boronic acid-terminated poly(aryl ether ketone) oligomers and smallorganic molecules with boroxines, denoted as PAEK-CB. Dependingon the feed molar ratio of the monomers, the PAEK-CB plastics canexhibit a tensile strength of similar to 46.7 MPa and a Young's modulus of similar to 1.21 GPa. Owing to the dynamic nature of boroxines, the PAEK-CB plastics can be depolymerized in theN-methylpyrrolidone/ethanol mixture solvent. Thus, the monomers can be easily andefficiently 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

Automated summary

This study presents a physically-recyclable plastic material, PAEK-CB, with high mechanical strength. The monomers of the material can be easily recovered and reused through depolymerization in a solvent, enabling closed-loop recycling of the plastic.