Roles of Ionic Liquids in Adjusting Nature of Ionogels: A Mini Review

Abstract

Over the past two decades, the unique features of ionic liquids (ILs) drive their exploration and exploitation in gel field and endow the gels with many excellent properties including thermal stability, antifreezing capability, mechanical strength, self-healing, conductivity, and antibacterial performance. As promising functional materials, ionogels have attracted remarkable interest in various applications including flexible electronics, energy storage, and biomedical applications. This review aims to give a detailed overview of the recent advances in developing of IL-based task-specific ionogels. The effects of ILs on the ionogels' formation and structure modification and their promotion on elevating these gel properties from the viewpoint of fundamental to the application are comprehensively discussed. The different interactions also discussed between ILs and other components in forming ionogels, such as hydrogen bond, electrostatic interaction, host-guest interaction, IL-philic and IL-phobic interaction, and introduced ILs' dissolvability to biomass; and the unique capability of ionogels owing to ILs, such as conductivity, electrochemical stability, thermal stability, and antibacterial ability. Finally, the future challenges and perspectives of ionogels are outlooked.

Soret Effect of Ionic Liquid Gels for Thermoelectric Conversion

“…In an ionogel, the ionic liquid is immobilized by the solid networks formed by the gelator . Various materials such as polymers, supermolecules, and nanoparticles can be used as the gelator materials of ionogels. − Scheme presents the chemical structures of some representative polymers as the gelator of ionogels. The microstructure of the solid networks in ionogels can be affected by the chemical structure and loading of the gelator.…”

“…This can affect the thermoelectric properties, including the ionic Seebeck coefficient and ionic conductivity, and the mechanical properties. 30 Ionogels are usually prepared from a solution of an ionic liquid and a polymer gelator through solution processing. Figure 2a presents the photo of an ionogel with 1-ethyl-3-methylimidazolium dicyanamide (EMIM:DCA) immobilized by poly-(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP).…”

“…The microstructure of the solid networks in ionogels can be affected by the chemical structure and loading of the gelator. This can affect the thermoelectric properties, including the ionic Seebeck coefficient and ionic conductivity, and the mechanical properties …”

A pH-Sensitive, Stretchable, Antibacterial Artificial Tongue Based on MXene Cross-Linked Ionogel

“…Therefore, it is a huge challenge to construct a framework system that can not only retain water but also possess excellent properties. Ionogel, a hydrogel-like gel material with a designable mechanism formed by confinement in a three-dimensional cross-linked network through distinct internal interactions, presents good properties, including higher ionic conductivity, enhanced antibacterial ability, improved thermal stability, , and antifreezing ability. , Furthermore, the ionic liquid in the ionogel has a lower vapor pressure, which ensures that the water in the whole system is not volatile and better solves the problem of water loss in the hydrogel . Also, the strong hydrogen bond interactions and electrostatic interactions provide guarantees for constructing high-strength ionogels. − …”

Ultra-stretchable, Antifatigue, Adhesive, and Self-Healing Hydrogels Based on the Amino Acid Derivative and Ionic Liquid for Flexible Strain Sensors

“…Ionic liquids (ILs), organic salt with a low melting point, have unique physical and chemical properties such as high ion conductivity, electrochemical stability, and wide-electrochemical windows. − Therefore, by incorporating ionic liquid into the hydrogel matrix, hydrogels became conductive and suitable for sensing materials . In this work, arginine derivative monomers and ionic liquid imidazolium salt-derived monomers were introduced into a hydrogel system by one-pot copolymerization.…”