European Polymer Journal, 2019, vol 116pp. 201-209
Polychaete worms display a remarkable jaw structure, where a gradient in metal-ligand coordination down the length of the jaw results in a shift from hard to soft mechanics. To mimic these gradient structures, a Zn-coordinated supramolecular polymer is crosslinked into a covalent matrix to afford supramolecular semi-interpenetrating networks (SIPNs). These SIPN materials exhibit improved mechanics with a lower supramolecular content (30?wt%), allowing for energy dissipation through cavitation to increase material toughness. The shift in mechanical behavior is further attributed to the morphology, where the size of the phase-separated droplets and nature of the continuous phase in these SIPNs contributes to the material mechanics. Furthermore, chemical gradients are applied to these systems through exposure to a competitive ligand, offering control over the localization of supramolecular interactions. These materials offer a framework to mediate mechanics while maintaining the ability to program gradient supramolecular interactions.