Peeling–Stiffening Self‐Adhesive Ionogel with Superhigh Interfacial Toughness

Abstract Self‐adhesive materials that can directly adhere to diverse solid surfaces are indispensable in modern life and technologies. However, it remains a challenge to develop self‐adhesive materials with strong adhesion while maintaining its intrinsic softness for efficient tackiness. Here, a peeling–stiffening self‐adhesive ionogel that reconciles the seemingly contradictory properties of softness and strong adhesion is reported. The ionogel contains two ionophilic repeating units with distinct associating affinities, which allows to adaptively wet rough surface in the soft dissipating state for adhering, and to dramatically stiffen to the glassy state upon peeling. The corresponding modulus increases by 117 times driven by strain‐rate‐induced phase separation, which greatly suppresses crack propagation and results in a super high interfacial toughness of 8046 J m −2 . The self‐adhesive ionogel is also transparent, self‐healable, recyclable, and can be easily removed by simple moisture treatment. This strategy provides a new way to design high‐performance self‐adhesive materials for intelligent soft devices.