In Situ Modification to Reinforce Isoprene Rubber by Sacrificial Bonds

Functionalization and reinforcement of polymers by introducing dynamic sacrificial bonds have attracted increasing attention. In this contribution, the in situ modification of isoprene rubber by the formation of sacrificial bonds during vulcanization has been investigated. The sacrificial bonds were formed by in situ introduction of hydrogen bonds and metal–ligand motifs, which became part of the vulcanized isoprene rubber network by reaction of the former with the vulcanizing agent. The introduction of three-component modifiers (nadic anhydride (NA), 2-aminopyrimidine (AP), and ZnCl2) and the molar ratio of these components can greatly affect the tensile strength and modulus of the vulcanized rubber. Under the external load, the sacrificial bonds preferentially rupture prior to the covalent network and facilitate rubber chain orientation, resulting in high fracture energy. In addition, the dynamic behavior of the sacrificial bonds and the hysteresis behavior of the vulcanized rubbers were studied.