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.