Coordination cross-linking of XNBR induced by different central ions

Metal–ligand bonding, as a tunable and reversible non-covalent interaction, is believed to improve composites' recyclability and self-healing ability. In this work, we prepared coordinated Carboxylated nitrile-butadiene rubber (XNBR) composites by mixing metal ions with NBR and hot pressing. X-ray photoelectron spectroscopy and infrared spectroscopy were used to characterize the metal-NBR complexes. The Arrhenius equation and bond valence-bond length theory also calculated the bonding capacity and bond energy to analyze the effect of coordination bonds on the self-repair of the materials in combination with the mechanical properties and molecular orbital theory. The results showed that Mg²⁺ didn’t react with cyano groups in coordination reactions. Cu²⁺ and Zn²⁺ coordinated with cyano groups at different temperatures. A comparison of the ligand bond energy and strength reveals that [Zn²⁺-N_B] was easier to form than [Cu³⁺-N_B]. The overall mechanical properties were improved due to non-covalent interactions, especially the self-repairing properties, which reached 93%. Therefore, the prepared XNBR/metal ions can play a significant role in practical applications in the industrial field.

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