Preparation and characterization of conductive and stretchable MXene-based nanocomposite hydrogels initiated by metal ions

Conductive hydrogels are emerging as an advanced electronic platform for wearable sensors by synergizing the advantageous features of conductivity and flexibility. Especially conductive polymer hydrogels have widespread applications in the fields of catalysis, biomedicine, monitoring, and wearable electronic skin owing to the outstanding strain sensitivity and resilience thereof. Nevertheless, how to maintain the conductivity of hydrogels and electronic skins under strain or deformation remains a significant challenge. To tackle the said bottleneck, a multiple H-bonding MXene-based conductive hydrogel was established in the present study. With the participation of MXene and Fe2+ ions, the hydrogel network was strengthened, which might be attributed to the H-bonding among the polymer chain, MXene, and Fe2+ ions. Meanwhile, the elongation at break and compression modulus of Poly(vinyl alcohol) (PVA)- M3F hydrogels increased to 513% and 85.6kPa compared with the initial PVA hydrogel, respectively. After incorporating Fe2+ ions, the PVA-M3F hydrogels exhibited greater conductivity, which was 7.9 x 10(-4)S/cm. Notably, the PVA-M3F hydrogels displayed good resilience, leading to stable conductivity and strain sensitivity. Subsequently, a finger joint was designed to verify the maintenance of conductivity and monitoring behaviors. PVA-M3F conductive hydrogel was found to possess an outstanding capability for electrical signals feedback and was expected to be applied to electronic sensors or monitors. In summary, the introduction of MXene and Fe2+ ions into PVA hydrogels can not only tune the conductivity but also have promising prospects as a countermeasure for wearable electronics.