Effect of Coordination Sacrificial Bond Strength on Toughening Properties of Polyesters

Abstract

By the coordination of dangling terpyridine (TPY) ligands with transition metal ions to form supramolecular crosslinking points as sacrificial bonds (SBs), a double-cross-linked system is constructed from the physically cross-linked semicrystalline polyesters. The mechanical properties are greatly enhanced, and the effect of coordination interaction strength on the toughening effect has been investigated by using different ions (Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ). It shows that stronger coordination bonds provide a larger Young's modulus, but not for strength and toughness, which increase first and then decrease after achieving a maximum value at an optimal SB strength. This is due to the properties estimated at different strains, where the supramolecular and physically cross-linking points behave differently. Our results demonstrate that SB strength is not the higher, the better, which should be useful for the design of strong and tough materials.