In Situ Mineralization for the Mechanical Reinforcement of Metal-Coordinate Polymer Hydrogels

Metal-coordination interactions are promising chemical motifs for the design of bioinspired polymeric materials that mimic the mechanical performance of biogenic materials such as the arthropod fangs and mussel byssal threads. Building upon the use of such motifs for the design of associative polymer gels, we demonstrate a bioinspired strategy to introduce additional mechanical reinforcement and novel functionalities into metal-coordinate hydrogels, by using the strongly metal-coordinating ligands as templates for the mineralization of metallic nanoparticles in the hydrogels <i>in situ. </i>We demonstrate ability to induce significant mineralization of iron oxide nanoparticles in a catechol-based polymer network, which results in significant stiffening (surpassing that arising from metal-ion coordination alone) as well as magneto-responsivity in the hydrogel. These findings further advance our utilization of metal-coordination interactions in bioinspired soft materials, and offer promise for their use in technological areas such as soft robotics, energy harvesting, and medicine.