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Metallosupramolecular High-Density Polyethylene as a Recyclable and Self-Healing Plastic
Summary
Researchers synthesized a mechanically robust metallosupramolecular polyethylene that mimics the performance of conventional high-density polyethylene while enabling rapid thermal self-healing and recyclability through reversible metal-ligand bonds. This addresses one of the core barriers to plastic circularity—the chemical inertness of polyethylene backbones—and could reduce the volume of PE waste that ultimately fragments into environmental microplastics.
Polyethylene (PE) is among the most widely used commodity materials, yet its chemically inert carbon-carbon backbones make recycling and reprocessing extremely challenging. In contrast, supramolecular polymers (SMPs) are inherently recyclable and reprocessable due to the presence of noncovalent bonds, which also confer attractive properties such as self-healing and stimuli responsiveness. However, achieving mechanical properties in SMPs comparable to those of conventional covalent polymers such as PE remains a major challenge. Here, we report a modular strategy for constructing mechanically robust metallosupramolecular polyethylene (MSPE) via metal-ligand chain extension of low-molecular-weight telechelic polyethylene motifs. Telechelic PE (TPE) analogues were synthesized via catalytic ring-opening metathesis polymerization of cis-cyclooctene in the presence of a chain-transfer agent bearing the metal-binding ligand 2,6-bis(1′-methylbenzimidazolyl)pyridine, followed by hydrogenation. Subsequent chain extension with zinc(II) bis(trifluoromethanesulfonyl)imide produced semicrystalline MSPE. By tuning the molecular weight of the TPEs and MSPEs’ processing conditions, materials with thermomechanical and mechanical properties closely resembling those of conventional high-density polyethylene were obtained. Importantly, dynamic metal-ligand interactions enable rapid thermal self-healing, recycling, and reusability, without loss of mechanical performance. This work establishes a design paradigm for high-performance supramolecular materials and offers a promising pathway toward recyclable commodity plastics with dynamic functionality.