Correlation between solvent composition and materials properties of organohydrogels prepared by solvent displacement

Abstract

Owing to their tunable functionality, structural flexibility, and biocompatibility, gels are widely utilized as active materials in applications, such as biomedical, sensors, and energy devices. Especially hydrogels, generally comprised of water over 80 vol%, are emphasized as attractive candidates for suggested applications. However, most devices based on hydrogels suffer from drying and freezing under practical operation environments. To overcome these issues, organohydrogels are proposed as good alternatives with improved durability. Although many organohydrogels with various polymer networks are reported, the effects of solvent system design on the properties of organohydrogels are still not conclusive. Here, we investigated the correlation between the solvent system design of organohydrogels and their properties, particularly in terms of rheological characteristics and ion conductivity. With increasing ethylene glycol content, the shear storage modulus and complex viscosity of the organohydrogels decrease sharply, possibly owing to the decrease in metal-carboxylate coordination in the gel network. The ion conductivity of the organohydrogels gradually decreases with increasing ethylene glycol content, owing to the ion conductivity trends of pure water and pure ethylene glycol ionic solution. Insight into the correlation between the solvent system design and properties of organohydrogels will enable the preparation of optimal organohydrogels for various processes and applications.