Quantifying force-induced bond dissociation in metal-coordinate gels under steady shear flow*

The dynamic nature of the bonds in associating polymer networks has led to its use in the design of tough and self-healing hydrogels. While the ability of the materials to regain its original stiffness after a recovery period has been documented, such data provides no information on the molecular level processes occurring as the network is damaged, and subsequently as it heals. In this work, the non-linear response of a model associative network, consisting of linear side-functionalized chains, with nickel-terpyridine complexation as the crosslinking group was investigated. With a custom-built setup, force-induced bond dissociation was quantitatively measured through fluorescence measurements, as the network was strained under steady shear. The measured fraction of dissociated bonds is compared to predictions of several models from transient network theory.