Tough Hydrogels Designed for a Stretch-Induced Decrease in Electrical Resistance Using Tandem Host-Guest and Ionic Cross-Linking.

Developing hydrogels that simultaneously exhibit mechanical toughness, interfacial adhesion, and a stretch-induced decline in electrical resistance remains a key challenge for soft and stretchable devices. Here, we present a supramolecular hydrogel system based on a tandem cross-linking strategy, formed through host-guest complexation between β-cyclodextrin (β-CD) and hydrophobic anions (TFSI- or NFO-), followed by sequential ionic interactions between anions and imidazolium polycations. The supramolecular hydrogels formed stable networks with enhanced mechanical strength, moderate swelling, and tunable adhesion, governed by the alkyl chain length of polycations, counteranions, and matrix polymers. Under tensile strain, the tandem cross-linked hydrogels exhibited a distinctive reduction in resistance, attributed to the sacrificial dissociation of dynamic cross-links that increase the anion mobility and facilitate ion transport. This supramolecular approach provides a versatile platform for designing robust, multifunctional hydrogels suited for mechanically demanding and stimuli-responsive applications with strong potential in flexible and wearable electronics.