Simultaneously enhancing the mechanical robustness and conductivity of ionogels by in situ formation of coordination complexes as physical crosslinks

Abstract

Ionogels with environmental tolerance have recently emerged as promising candidates for use in flexible electronics. However, a challenge still exists in simultaneously enhancing the mechanical robustness and conductivity of ionogels. In this paper, we demonstrate a facile and fast novel strategy for forming a high-strength metal-coordinated solvent-free ionogel through in situ polymerization in one pot. The resulting iongel exhibits high tensile strength (5.68 MPa) and elongation at break (600%) due to the presence of imidazole nitrogen–Ni²⁺ coordination complexes as physical crosslinks. Furthermore, the conductivity of the ionogel is increased to 68.63 × 10⁻³ S m⁻¹ by incorporating metal ions as conductive fillers, which is 10 times higher than that of the ionogel without metal ions prepared under the same conditions. The strategy, based on the universal coordination between imidazole nitrogen and multivalent metal ions, is highly versatile and can be applied to a wide range of metal ions (Co²⁺/Zn²⁺). The ionogel can be utilized in the assembly of strain sensing and humidity sensors for human health monitoring. Additionally, its fast photo curing properties make it suitable as a 3D printing ink for customizing tough pressure sensors with microstructures, demonstrating its potential as an engineering material and wearable sensor.