Construction of high-strength, super-adhesive conductive hydrogel based on dopamine-modified carboxymethyl cellulose under the multi-effect of iron ions

Based on conductive hydrogels, flexible wearable sensors struggle to balance high mechanical strength with strong adhesion properties. This study employed dopamine-modified carboxymethyl cellulose (CMC-DA), acrylamide (AM), and hexadecyl methacrylate (HMA) to construct a double-network hydrogel with hydrophobic associations and complexation structures. In the preparation process, Fe 2+ initially complexes with the catechol groups in DA-CMC, thereby protecting them from oxidation by ammonium persulfate (APS). Subsequently, APS and N,N,N′,N′-tetramethylenediamine (TMEDA) are employed to initiate a hydrophobic association system involving acrylamide (AM) and hydroxyethyl methacrylate (HMA). Concurrently, Fe 2+ released from the complexation equilibrium undergoes a redox reaction with APS. The generated Fe 3+ ions, which exhibit enhanced complexation capabilities, facilitate the formation of a more robust complexation gel network with CMC-DA. Consequently, the resulting dual-network gel demonstrates exceptional mechanical properties, electrical conductivity, and self-recovery performance, along with strong adhesion. This study also expands the potential applications of hydrogels in flexible wearable sensors.