Highly Stretchable, Low-Hysteresis, and Adhesive TA@MXene-Composited Organohydrogels for Durable Wearable Sensors

As wearable sensors advance rapidly, demands for multifunctional conductive soft materials are ever higher, including high stretchability, resilience, adhesiveness and stability, simultaneously in one material, for stable long-term use. Nanocomposite hydrogels incorporating conductive two-dimensional (2D) nanofillers, such as MXene-composited gels, emerge as promising candidates. Yet, fulfilling all above requirements, particularly large stretchability with low hysteresis, remains a challenge, owing to the easy oxidation and weak interactions of MXene nanosheets with polymer chains. Herein, an interfacial engineering strategy is proposed, where tannic acid (TA) with high-density hydroxyl groups is introduced to encapsulate MXene into a stable TA@MXene nano-motif and meanwhile increase the hydrogen-bonding interactions between TA@MXene and polymer network. By incorporating TA@MXene into poly(hydroxyethyl acrylate) (PHEA) network in a glycerol/water binary solvent, the obtained organohydrogel exhibits integrated properties of high stretchability (>500%) with low hysteresis (<3%), superior fatigue resistance (consistent hysteresis over 500 cycles at 300% strain), good adhesiveness, along with long-term stability (>7 days) and antifreezing abilities (−40 °C). Such organohydrogels demonstrate superior strain-sensitivity and thermosensitive capacities, enabling accurate and reliable detection of human movements, electrocardiogram signals, and body temperature. This general approach of stabilizing nanomaterials while effectively enhancing nanomaterial-polymer bonding is applicable for synthesizing diverse high-performance nanocomposited gels.