Double-Cross-Linked and Stretchable Ionogels with Tunable Mechanics and Ionic Conductivity for Thermal and Mechanical Sensors.

Ionogels have emerged as promising materials for flexible sensors due to excellent thermal stability, high ionic conductivity, and nonvolatility. However, the high ionic liquid content required for optimal conductivity usually compromises the mechanical integrity of the ionogels. Here, we present a strategy through copolymerization of amino-terminated liquid crystalline poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) and flexible poly(acrylic acid) (PAA), which forms a double-cross-linked ionogel that effectively couples high ionic conductivity with enhanced mechanical properties. By enabling stress transfer between the rigid and soft segments, this approach allows PBDT segments to align under deformation, simultaneously boosting ionic conductivity (1.6 mS cm) and mechanical modulus (43 MPa); meanwhile, the PAA segments offer high flexibility with 900% elongation in the ionogels. The ionogels exhibit exceptional durability over numerous stretching cycles at different strain levels, while maintaining strong thermal sensitivity across a broad temperature range (-60 to 140 °C), making them well-suited for real-time monitoring in diverse environments. This advancement not only overcomes the longstanding trade-off of modulus and conductivity in ionogels but also shows the promise of polymeric ionogels for next-generation sensing technologies.