Supramolecular Ionic Gels for Stretchable Electronics and Future Directions
Shunsuke Yamada, T. Honda
Abstract
Ionic gels (IGs), ionic liquids (ILs) dispersed in polymers, exhibit extremely low vapor pressure, electrochemical and thermal stability, and excellent mechanical characteristics; therefore, they are used for fabricating stretchable sensors, electrochemical transistors, and energy storage devices. Although such characteristics are promising for flexible and stretchable electronics, the mechanical stress-induced ruptured covalent bonds forming polymer networks cannot recover owing to the irreversible interaction between the bonds. Physical cross-linking via noncovalent bonds enables the interaction of polymers and ILs to form supramolecular IGs (SIGs), which exhibit favorable characteristics for wearable devices that conventional IGs with noncovalent bonds cannot achieve. Herein, we review recent material designs and interactions used for fabricating SIGs, such as ionic interactions and hydrogen bonding. We present SIG characteristics achieved via the interaction of polymers and ILs, such as extreme toughness, self-healing capability, and self-adhesion favorable for human body sensors. We conclude this Perspective by discussing the potential of SIGs as a power source for implants, wearable devices, and environmental sensing applications.