High-strength, ultra-tough and recyclable MXene-composited organohydrogels with integrated multiple functions for wearable sensors

Abstract

Multifunctional conductive hydrogels are widely used as promising candidates for flexible sensors. For these applications, gels with integrated multiple performances, particularly the combination of high mechanical strength and recyclability, are highly desirable but can be rarely achieved in one gel. Here, a MXene-composited organohydrogel is prepared by a facile freezing–thawing process with the incorporation of tannic acid-modified MXene (TA@MXene) into a poly(vinyl alcohol) (PVA) network in glycerol/water solvent. The introduction of TA can largely improve the stability of MXene in aqueous solution, and meanwhile induces the formation of abundant hydrogen bonds between PVA chains and TA@MXene. The obtained organohydrogel exhibits high tensile strength (3.55 MPa), ultrahigh toughness (9.93 MJ m⁻³), superior anti-freezing ability (−40 °C), good long-term stability (≥20 days), and remarkable ultraviolet (UV) light filtering capabilities. Interestingly, owing to the reversibility of non-covalent crosslinked structures, the organohydrogel can be recycled and reused by a hot melting–cooling process. Moreover, the organohydrogel-based wearable sensors show high strain sensitivity in a large strain range, which can be used to monitor various human movements and physiological activities, even under harsh conditions or after recycling. This work gives new perspectives for the preparation of high-strength and recyclable gels with multiple functions for flexible sensors.