Hybrid double-network dual-crosslinked hydrogel with self-healing ability and mechanical stability. Synthesis, characterization and application for motion sensors

The growing list of potential applications of soft materials increases the demand for, among others, new multifunctional hydrogels. We propose a hybrid double-network hydrogel based on synthetic poly(acrylic acid) and alginate, a natural polymer. These polymer networks were double crosslinked: chemically and physically. The ferrous ion was used to catalyze the decomposition of the initiator and later, after its oxidation by the initiator to the ferric ion, was coordinated by the carboxylic groups of the polymer networks and acted as a physicochemical crosslinker. The composition of the hydrogel was optimized to get improved mechanical and electrical properties, and the self-healing ability. The introduction of the coordination bond between Fe3+ and the carboxylic groups of AA and alginate molecules created the ability of self-healing of the hydrogels; they could regenerate without any external stimulus and regain their electrical conductivity and mechanical properties.