Environmentally adaptive self-healing hydrogels via multiscale control of water molecules for human-machine interaction

Self-healing hydrogels can autonomously restore their structural integrity and functionality after injury. However, their self-repair capability is often compromised by water evaporation at high temperatures (> 30 °C) or crystallization at cryogenic conditions (< −20 °C). Here, we introduce a “Li + -hydration-coordination synergistic water-locking” strategy, which immobilizes water molecules within the hydrogel network via water-locking structures formed by a robust hydration shell ([Li(H 2 O) 4 ] + ) and polymer-ionic-water complexes ([Li(CO-PAM)(H 2 O) 4 ] + ). Under this water-locking mode, the Li + -hydrogels maintain their softness even under harsh enviromental conditions, which facilitates the dynamic reconfiguration of self-healing bonds within the polymer network. As a result, the healed Li + -hydrogels exhibit a stretchability/tensile strength of up to 780 %/30 kPa, 1024 %/193 kPa, and 620 %/525 kPa at −60 °C, 25 °C, and 80 °C, corresponding to healing efficiencies of 75 %, 98 %, and 60 %, respectively. Additionally, it also demonstrates wide strain-sensing range (0.1 %–600 %), rapid response time (80 ms) and excellent cycle stability (2000 cycles), which can be successfully employed in human-machine interaction. This strategy establishes a design paradigm for environmentally adaptive composite materials through multiscale control of ion-mediated water molecules.