Mass-Produced Chemically Recyclable Aromatic Polymers with Exceptional Strength and Stability

Developing chemically recyclable polymers that offer ultrahigh mechanical strength, exceptional chemical stability, mild recycling conditions, and scalability for mass production remains a significant challenge. This study presents a novel class of chemically recyclable plastics, synthesized at kilogram scale in the laboratory, by reversibly cross-linking aromatic polyamide macromonomers with boroxines, imine bonds, and hydrogen bonds. These plastics, denoted as PA-B₃O₃, exhibit an impressive tensile strength of 142.1 MPa, a Young's modulus of 2.39 GPa, a glass transition temperature of ∼211.6 °C, and outstanding chemical resistance to acidic/basic aqueous solutions and organic solvents. PA-B₃O₃ plastics can be depolymerized in a mixed solvent of <i>N</i>,<i>N</i>-dimethylacetamide and aqueous HCl solution, allowing for efficient recovery of the original amino-terminated polyamide (PA-NH₂) via precipitation in selective solvents, even when mixed with polymer waste streams. This study represents a significant advancement toward the practical application of mechanically robust, chemically resistant, and recyclable polymers.