A Waterproof Ion‐Conducting Fluorinated Elastomer with 6000% Stretchability, Superior Ionic Conductivity, and Harsh Environment Tolerance

Abstract The development of ionic conductors with extreme stretchability, superior ionic conductivity, and harsh‐environment resistance is urgent while challenging because the tailoring of these performances is mutually exclusive. Herein, a hydrophobicity‐constrained association strategy is presented for fabricating a liquid‐free ion‐conducting fluorinated elastomer (ICFE) with microphase‐separated structures. Hydrophilic nanodomains with long‐range ordering and selectively enriched Li ions provided high‐efficient conductive pathways, yielding impressive room‐temperature ionic conductivity of 3.5 × 10 –3 S m –1 . Hydrophobic nanodomains with abundant and reversible hydrogen bonds endow the ICFE with superior damage‐tolerant performances including ultrastretchability (>6000%), large toughness (17.1 MJ m –3 ) with notch insensitivity, antifatigue ability, and high‐efficiency self‐healability. Due to its liquid‐free characteristic and surface‐enriched hydrophobic nanodomains, the ICFE demonstrates an extreme temperature tolerance (−20 to 300 °C) and unique underwater resistance. The resultant ICFE is assembled into a proof‐of‐concept skin‐inspired sensor, showing impressive capacitive sensing performance with high sensitivity and wide‐strain‐range linearity (gauge factor to 1.0 in a strain range of 0–350%), excellent durability (>1000 cycles), and unique waterproofness in monitoring of complex human motions. It is believed that the hydrophobicity‐constrained association method boosts the fabrication of stretchable ionic conductors holding a great promise in skin‐inspired ionotronics with harsh‐environment tolerance.