Self-Healable, Recyclable, and Ultrastrong Adhesive Ionogel for Multifunctional Strain Sensor

Abstract

Flexible electronic materials have aroused significant interest due to the need for flexible electronics in a variety of applications. However, several obstacles such as low mechanical properties, interfacial adhesion problems, and nonreusability hinder their rapid development. Here, an ionogel was developed by a onestep photopolymerization of an ionic liquid (IL) with the CC bond of 1-vinyl-3-butylimidazolium tetrafluoroborate in another ionic liquid solution of 1-butyl-3-methylimidazolium tetrafluoroborate without a chemical cross-linker. The poly(ionic liquid) and the ionic liquid (PIL/IL) were highly compatible and resulted in an extremely uniform, stable, and optically transparent PIL/IL ionogel. In addition, this method also avoided complicated solvent replacement in the preparation processes of common ionogels. Our experimental and theoretical results showed that the reported ionogel integrated excellent mechanical properties, ultrastrong adhesive, self-healability, and recyclability. These remarkable advantages were benefited from the strong electrostatic force and other noncovalent bond interactions in the ionogel system. The unique ionogel presented in this study is therefore an ideal candidate material for self-adhesive and reusable wearable electronics.

Highly Stretchable, Fast Self-Healing, and Waterproof Fluorinated Copolymer Ionogels with Selectively Enriched Ionic Liquids for Human-Motion Detection

“…Skin-inspired wearable sensors that imitate human skin perception characteristics have drawn intensive attention due to their application prospects in the emerging fields of health monitoring, − soft robotics, − and human–machine interfaces. , Skin-inspired wearable sensors can be generally categorized into two types of electronic skins (e-skins) , and ionic skins (i-skins). − Unlike the e-skins using electric conductors that transduce response signals by electronic conduction, i-skins, using ionic conductors that sense external stimuli based on ionic conduction, are promising to achieve the functions of human skin due to the advantages of transparency, intrinsic stretchability, and high sensitivity. − However, i-skins are practically faced with complex deformation or continuous mechanical loading, requiring ionic conductors with high stretchability and mechanical robustness. , Moreover, high stability under high moistures and water environments is another important property for the durability of i-skins. Thus, the development of ionic conductors with extensive stretchability, high mechanical elasticity, and unique underwater stability is significant for the development of next-generation skin-inspired sensors.…”

Highly Stretchable, Adhesive Ionic Liquid-Containing Nanocomposite Hydrogel for Self-Powered Multifunctional Strain Sensors with Temperature Tolerance

“…It was worth noting that the P­(AAm- co -HEA)/Laponite XLG ionogel could still adhere to two pieces of steel under water and bear a weight of 100 g. Moreover, it was easy to adhere to human skin and fit different angles of the joint, reflecting the potential as a sensor for detecting joint movements (Figure S17). The excellent adhesion of the ionogel is probably attributed to various supramolecular interactions like hydrogen bonding, electronic interactions, and van der Waals interactions between the P­(AAm- co -HEA)/Laponite XLG ionogel and various contact substrates. , Subsequently, the P­(AAm- co -HEA)/Laponite XLG ionogels were adhered to the surfaces of two pieces of materials (glass, plastic, aluminum, and cooper) to form a contact area. The adhesive strength was quantitatively studied by a lap shear test.…”

“…The excellent adhesion of the ionogel is probably attributed to various supramolecular interactions like hydrogen bonding, electronic interactions, and van der Waals interactions between the P(AAm-co-HEA)/ Laponite XLG ionogel and various contact substrates. 37,39 Subsequently, the P(AAm-co-HEA)/Laponite XLG ionogels were adhered to the surfaces of two pieces of materials (glass, plastic, aluminum, and cooper) to form a contact area. The adhesive strength was quantitatively studied by a lap shear test.…”

“…Generally speaking, the 3D polymer networks can provide good mechanical behavior and good integrity. Meanwhile, ionic liquids present ionic conductivity, thermal and chemical stability, nonflammability, and nonvolatility, which provide a wide working range for the ionogel device. , However, ionogels usually suffer from limited stretchability and self-adhesion, which hinder their applications . Nie and co-workers reported a robust double-network ionogel as a high-performance strain bimodal sensor with a wide sensing temperature range from 60 to −30 °C .…”

Photopolymerizable Ionogel with Healable Properties Based on Dioxaborolane Vitrimer Chemistry

“…Imparting ionogels with healing ability seems to be a promising approach because of their capability to repair mechanically induced damage. Hydrogen bonds, ionic bonds, and metal–ligand coordination have all been explored to develop healable ionogels [ 10 , 11 , 12 , 13 ]. Even though ionic and hydrogen bonds have been shown to demonstrate effective self-healing properties, these physical networks are generally vulnerable to heat, water, and other polar solvents.…”