Healable, Recyclable, and Mechanically Tough Polyurethane Elastomers with Exceptional Damage Tolerance

TLDR

Elastomers are essential for tires, seals, and shock absorbers, yet sustainable variants that combine healing, recycling, damage tolerance, high strength, elasticity, and toughness remain elusive because these properties are mutually exclusive. The study aims to fabricate healable, recyclable, and mechanically tough polyurethane elastomers with exceptional damage tolerance by coordinating multiblock PDMS/PCL polymers with Zn²⁺ ions. Dynamic hierarchical domains formed by bipyridine–Zn²⁺ coordination, hydrogen‑bonded carbamate crosslinks, and crystallized PCL segments act as rigid nanofillers that enhance toughness and fracture energy while enabling healing and recycling. The resulting elastomers achieve a tensile strength of ~52.4 MPa, toughness of ~363.8 MJ m⁻³, and fracture energy of ~192.9 kJ m⁻².

Abstract

Abstract There is a huge requirement of elastomers for use in tires, seals, and shock absorbers every year worldwide. In view of a sustainable society, the next generation of elastomers is expected to combine outstanding healing, recycling, and damage‐tolerant capacities with high strength, elasticity, and toughness. However, it remains challenging to fabricate such elastomers because the mechanisms for the properties mentioned above are mutually exclusive. Herein, the fabrication of healable, recyclable, and mechanically tough polyurethane (PU) elastomers with outstanding damage tolerance by coordination of multiblock polymers of poly(dimethylsiloxane) (PDMS)/polycaprolactone (PCL) containing hydrogen and coordination bonding motifs with Zn 2+ ions is reported. The organization of bipyridine groups coordinated with Zn 2+ ions, carbamate groups cross‐linked with hydrogen bonds, and crystallized PCL segments generates phase‐separated dynamic hierarchical domains. Serving as rigid nanofillers capable of deformation and disintegration under an external force, the dynamic hierarchical domains can strengthen the elastomers and significantly enhance their toughness and fracture energy. As a result, the elastomers exhibit a tensile strength of ≈52.4 MPa, a toughness of ≈363.8 MJ m −3 , and an exceptional fracture energy of ≈192.9 kJ m −2 . Furthermore, the elastomers can be conveniently healed and recycled to regain their original mechanical properties and integrity under heating.