A co-assembly strategy for the construction of robust, recyclable and multifunctional crosslinked metal–organic polyhedra using aromatic polyamides

Metal-organic polyhedra (MOP)-based composites have emerged as promising candidates for various applications owing to their unique structure. However, the construction of strong and recyclable MOP-based composites with novel functionalities is challenging. Herein, by using telechelic aromatic polyamides as macromolecular ligands, crosslinked MOP polyamides (LODA-MOPs) were constructed <i>via</i> coordination with copper ions (Cu²⁺). Isophthalic acids were further introduced to co-assemble with the macromolecular ligands, with the aim of tailoring the crosslinked structure and increasing the fraction of MOPs. The LODA-MOPs showed excellent mechanical properties that surpassed those of other MOP-based composites as well as exhibited good chemical/thermal resistance owing to the optimized crosslinked structure and robust polyamide matrix. The ligand exchange capability of MOPs permits recycling of the LODA-MOPs, as confirmed by the identical structure and properties of recycled samples. The polar groups in MOPs and loosened chain packing endow LODA-MOPs with intense and rapid humidity responsiveness, which is nearly 20 times that of linear polyamides, making them good candidates for humidity actuators. The crosslinking with MOPs also significantly improves the dielectric constant, breakdown strength and energy density when utilized in energy storage devices. Furthermore, the improved performance by using LODA-MOPs as a negative-charge layer in TENG systems is demonstrated.