Hofmeister effect-inspired Ti3C2Tx MXene-based robust, multifunctional hydrogels

Developing multifunctional hydrogels with high strength, toughness, and conductivity is critical for various applications in soft robots, wearable devices, and human–computer interfaces. Inspired by the Hofmeister effect, a type of composite hydrogels was prepared using a freezing and salting-out approach, which combines transition metal carbide/nitride (MXene) and polyvinyl alcohol (PVA). The hydrogels exhibited great mechanical strength and toughness, and high conductivity, conferring its application as a multifunctional strain sensor. In addition, the synergy of highly conductive MXene, water-enriched porous structure, and sufficient MXene-PVA interfaces contributes to the controllable and high electromagnetic interference shielding effectiveness of 43–93 dB at thickness of 1.5–8.5 mm. Combined with the facile and scalable preparation approach for rational design of the MXene, PVA, water, and porous structure in the hydrogels, this work thus demonstrates the robust, ultra-flexible and electrically conductive multifunctional hydrogels for applications in Internet of Things, next-generation wearable electronics, electromagnetic protection, and smart devices.