Self-healable recyclable thermoplastic polyurethane elastomers: Enabled by metal–ligand bonds between the cerium(III) triflate and phloretin

This study initially developed highly efficient self-healing materials with cerium(III) triflate [Ce(SO3CF3)3] as the metal center and phloretin as the ligand to synthesize a self-healable polyurethane elastomer with excellent self-healable and mechanical properties. Nuclear magnetic resonance data from experimental research on the self-healing mechanism indicated that Ce(SO3CF3)3 and phloretin could effectively form coordination bonds. Then, the hydroxyl group (−OH) on the para position of the phloretin reacted with the isocyanate group in the polyurethane prepolymer to form coordination-bond-facilitated self-healable polyurethane elastomers. An optimal sample (PUPC-2) with high tensile strength (5.17 Mpa) and high stretchability (1,415.7%), ideal toughness (35.08 MJ m−3), and remarkable healing efficiency (near to 100% healed after 48 h at room temperature) was obtained. In addition, the PUPC sample also exhibited good thermoplasticity, which means that the self-healable polyurethane elastomer can be recycled. These excellent performances ensure that the self-healable thermoplastic polyurethane elastomers have a wide range of practical applications. Therefore, a flexible conductive electrode with a self-healable capacity was obtained by compositing the PUPC-2 sample with flexible graphene-based conductive paper, which demonstrated good potential for application in the field of wearable devices and flexible electronics.