Thermal-responsive, self-healable, self-adhesive and degradable MXene-based ionic hydrogels for multifunctional sensors

Conductive hydrogels combining thermal responsiveness, stretchability, adhesiveness, self-healing, reusability, and degradability are highly desirable for next-generation wearable and multifunctional devices; however, achieving these properties in a single system remains challenging. Herein, we report a multifunctional hydrogel constructed from polyvinyl alcohol (PVA), borax, and MXene nanosheets and an ionic liquid monomer of tetrabutylphosphonium styrene sulfonate (PSS). The resulting PVA–borax–ionic liquid–MXene hydrogel (PBILM) exhibited a distinct lower critical solution temperature (LCST)-type phase transition behavior, enabling thermal responsiveness from 20 to 60 °C. The incorporation of MXenes enhances both the electrical conductivity and self-healing efficiency via dynamic interactions with the polymer network. The obtained PVA-Borax-MXene-Ionic Liquid (PBILM) hydrogel demonstrates rapid gelation (within 10 s), excellent thermal responsiveness, fast self-healing capabilities, extreme stretchability (>2000 %), strong adhesion, and degradability. These features make it highly versatile for detecting various external stimuli and human movements, including handwriting, Morse code signals, and joint motion monitoring. Furthermore, the PBILM hydrogel exhibited swift degradation in H 2 O 2 solution (within 62 min), deionized (DI) water (H 2 O) (within 6 h) and phosphate-buffered saline (PBS) solution (within 24 h), ensuring an environmentally friendly profile with minimal ecological impact. This study offers a promising strategy for developing smart, degradable, and multifunctional hydrogels for wearable electronics, as well as environmentally sustainable applications such as agricultural carriers or water treatment. • A novel MXene-based hydrogel uses a thermoresponsive ionic liquid matrix. • The hydrogel shows self-healing, self-adhesion, and extreme stretchability (>2000 %). • Rapid degradability in water enables environmentally friendly sensing applications. • Exhibits reversible transparency and thermal sensitivity from 20 °C to 60 °C. • Demonstrates potential in wearable sensors, data encryption, and information display.