Supramolecular Mismatch Elevates the Flow Transition Temperature of Ionogels

ABSTRACT Ionogels, formed by integrating polymer networks with ionic liquids (ILs), are promising for flexible electronics and ionotronic devices, yet their practical application is often limited by poor high‐temperature stability arising from low flow transition temperatures ( T f ), which are commonly reduced upon incorporation of ILs. Here, we report a supramolecular mismatch strategy that fundamentally elevates the T f of polyurethane‐based ionogels, effectively suppressing thermal softening under heating. By introducing mismatched supramolecular chain extenders into the polymer backbone, the resulting ionogels exhibit a markedly increased T f of up to 151°C and a substantially expanded operating temperature window approaching 200°C. Rheological measurements reveal a markedly higher loss modulus for the mismatched ionogel at elevated temperatures, indicating enhanced internal friction that stabilizes the network against thermal flow. Importantly, this strategy mitigates the disruptive effect of ILs on polymer–polymer interactions while maintaining high ionic conductivity and optical transparency. Beyond thermal stability, the ionogels also display good elasticity, self‐healing capability, and stable sensing performance at elevated temperatures. This work establishes supramolecular mismatch as a powerful design principle for overcoming the intrinsic thermal limitations of ionogels, enabling their use in wide‐temperature‐range soft electronic and sensing applications.