Fe³⁺-, pH-, Thermoresponsive Supramolecular Hydrogel with Multishape Memory Effect

Poor, nontunable mechanical properties as well as finite shape memory performance pose a barrier to shape memory hydrogels to realize practical applications. Here, a new shape memory hydrogel with tunable mechanical properties and multishape memory effect was presented. Three programmable reversible systems including PBA-diol ester bonds, AAc-Fe³⁺, and coil-helix transition of agar were applied to memorize temporary shapes and endow the hydrogel with outstanding multishape memory functionalities. Moreover, through changing the cross-linking densities, the mechanical properties of the as-prepared hydrogel can be adjusted.