Toughening Ionogel via Side-Chain Liquid Crystal-Induced Microphase Separation

Ionogels, owing to their excellent ionic conductivity, thermal stability, and nonvolatility, are compelling candidates for flexible ionotronic devices. However, developing ionogels that simultaneously combine a high mechanical performance with intelligent sensing capabilities remains a challenge. To address this, a side-chain liquid crystal-induced microphase separation strategy is proposed for toughening ionogels. This approach employs a one-pot, UV-triggered copolymerization of side-chain liquid crystal monomer and polymerizable ionic liquid monomer in the nonpolymerizable ionic liquid to fabricate a tough ionogel with tunable side-chain liquid crystal-induced microphase separation, thereby achieving tunable mechanical properties. By regulating the concentration of side-chain liquid crystal monomer, the toughened ionogel achieves a tensile strength of 1.65 MPa, a fracture toughness of 4 MJ m–3, and an elongation at break of 360%. In the toughened ionogel, the side-chain liquid crystal-induced microphase separated domains provide physical cross-link that contribute to network reinforcement, whereas the poly(ionic liquid)-rich domains maintain flexibility and enable ion transport. Furthermore, toughened ionogel-based strain sensors were fabricated, which exhibited high sensitivity and robust cycling stability, enabling real-time monitoring of physiological signals and making them suitable for wearable sensing applications. This microphase separation enabled reinforcement strategy is broadly applicable, opening an avenue for tailoring the microstructure and properties of ionogels through molecular design.