Recyclable, tough, bioinspired metal-coordination epoxy thermoset capable of intelligent temperature detection

Traditional epoxy thermosets are of technological significance for composite materials and smart device. But unsatisfactory degradability and extensibility limit its further development. For the thermosetting polymer, most properties can be achieved by engineering the cross-linked points and molecular chain structure. Inspired by the mussel, the epoxy network containing abundant imidazole-metal coordination bonds was constructed via designing a hardener similar to histidine. Those sacrificial coordination crosslinks provided high-efficiency access to energy dissipation, improving material's stiffness and extensibility simultaneously. Optimal tensile toughness and impact strength were up to 15.92 MJ/m3 and 15.17 KJ/m2, which were about 4.7 and 1.8 folds of Neat EP. Notedly, such epoxy thermosets with reversible coordination motifs and flexible molecular chain were capable of thermal-driven shape memorizing and programming repeatedly. Based on this special feature, the intelligent temperature warning sensor was designed successfully, which embodied good sensitivity and demonstrated rapid detection response time within ∼1s. Meanwhile, the pH-susceptive motifs (imine bonds and coordination bonds) allowed the epoxy networks to be decomposed quickly, so as to realize the efficiently recycling of high-value Au particles. This work provided a flexible and practical platform for the exploration of multifunction and intellectualization of conventional thermosetting materials.