Design of Nitrile Rubber with High Strength and Recycling Ability Based on Fe3+–Catechol Group Coordination

In this work, nitrile rubber (NBR) with high strength and recycling ability was designed based on the interaction between metal ions and ligands. Herein, we first epoxidized the nitrile rubber latex through the peroxyformic acid method. Dopamine was then grafted onto the epoxidized nitrile rubber via the ring-opening reaction followed by the introduction of Fe3+, which formed Fe3+–catechol group coordination bonds and acted as dynamic cross-linking points to connect separate NBR molecules. The NBR exhibited valuable mechanical properties due to the formation of the Fe3+–catechol group coordination bonds. For example, the tensile strength of modified NBR with 2.5 phr Fe3+ reached 8.93 MPa, which was far higher than that of most reported noncovalent supramolecular rubbers. Meanwhile, the reversible association–dissociation behavior of the Fe3+–catechol group coordination bonds endows NBR with excellent recycling ability (about 90% performance retention rate), which is considerably distinguished from that of conventional vulcanized rubber. The design of the recyclable cross-linked NBR with considerable mechanical properties is significantly meaningful in resource savings and environmentally friendly performance.