Polysaccharide/Ti3C2Tx MXene adhesive hydrogels with self-healing ability for multifunctional and sensitive sensors

Integrating functionalities such as adhesiveness, self-healing, and conductivity on a polysaccharide-based hydrogel is highly desirable for ever-expanding practical applications, but there is always a challenge. Herein, an elaborately designed nanocomposite hydrogel is fabricated by the addition of highly conductive Ti3C2Tx MXene nanosheets into chondroitin sulfate (CS)/N, N-dimethylamino ethyl acrylate (DMAEA-Q) hydrogel network. Owing to the introduction of sulfonated Ti3C2Tx MXene nanosheets, the as-prepared nanocomposite hydrogels exhibit excellent stretchability (> 5000% strain), rapid self-healing ability (< 60 s), and high adhesiveness (≈ 100 kPa). The proposed hydrogel demonstrates an outstanding electrical conductivity up to 5.33 S/m, allowing real-time monitoring of the bending and stretching movements and full recovery. Furthermore, the SMC hydrogels exhibit fast and stable photothermal conversion performance due to the inherent photothermal behavior. Notably, multifunctional SMC hydrogels present real-time and reversible humidity sensing upon H2O-induced swelling/contraction of nanochannels between the Ti3C2Tx MXene interlayers, enabling respiration monitoring applications.