Thermoreversible Nitrile Rubber Based on the Dual Role of Zinc Chloride.

A strategy for the preparation of thermoreversible nitrile rubber is demonstrated by introducing zinc chloride into sulfur‐cured nitrile rubber to form metal coordination bonds, thereby constructing a dynamic double‐crosslinking network as a potential solution for the severe environmental burden. In this study, the crosslinking structure and the mechanism of reprocessing are investigated by X‐ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy, revealing that the crosslinking network is formed by monosulfide bonds, disulfide bonds, polysulfide bonds, and Zn2+‐cyanide coordination bonds generated from zinc chloride that interact with the cyano groups on the nitrile rubber. Zinc chloride plays a dual role during the reprocessing process. On one hand, it participates in the cleavage/recombination of Zn2+‐cyanide coordination bonds. On the other hand, it catalyzes the disulfide exchange reaction in the sulfur crosslinking system, enabling the recycled nitrile rubber to possess recyclability. Due to the double‐crosslinking structure accompanied by the dual role of zinc chloride, nitrile rubber exhibits superior mechanical properties and impressive recyclability. The tensile strength and elongation at break of the double‐crosslinking nitrile rubber reach 5.59 MPa and 387%, respectively, stronger than those of sulfur‐cured nitrile rubber, maintaining 116.5% and 115.0% after the recycling process. [ABSTRACT FROM AUTHOR]