Tough Ionogels by Tuning Interactions Between Solvent and Polymer Networks

Ionogels are compelling materials for technological devices due to their excellent ionic conductivity, thermal and electrochemical stability, and non-volatility. However, most existing ionogels suffer from low strength and toughness. Here, we report simple one-step methods to achieve ultra-tough and stretchable ionogels by tuning solvents (<i>i.e.</i>, ionic liquids)-polymer chains dipole-dipole interactions. In poor solvents, the polymer chains in the network can form phase separation that act as sacrificial bonds to toughen the ionogel. By contrast, in good solvents, the polymer chains are highly solvated and can form strong interactions (noncovalent crosslinks) with the solvent. These noncovalent interactions can be broken to dissipate energy and thus toughen the ionogels. The ionogels achieved by these strategies showed extremely high fracture strength (10-80 MPa), fracture energy (~24 kJ m⁻²) and Young’s modulus (50-1,000 MPa), while being highly stretchable (400-800% strain) and having self-healing and shape-memory properties. Importantly, these strategies are proved to be generalized, which offer a promising way to tough ionogel and may help to expand their applications.