Highly Stretchable, Transparent, Solvent-Resistant Multifunctional Ionogel with Underwater Self-Healing and Adhesion for Wearable Strain Sensors and Barrier-Free Information Transfer.

Ionogels with excellent deformability, high ionic conductivity, and a sensitive stimulus response have been widely used and rapidly developed in flexible wearable systems. However, previously reported ionogels are mainly limited to atmospheric environments applications and have difficulty meeting the requirements of solvent-resistant, self-healing, and adhesion properties in underwater environments. Herein, a multifunctional ionogel capable of underwater applications is prepared by one-step photoinitiated polymerization of a fluorine-containing monomer (2,2,3,4,4,4-hexafluorobutyl acrylate, HFBA) and acrylic acid (AA) in a hydrophobic ionic liquid ([EMIM][TFSI]). The dynamic physical interactions of hydrogen bonds and ionic dipoles endow the ionogel with remarkable transparency, tunable mechanical properties, and underwater self-healing properties. Moreover, the fluoropolymer matrix offers high resistance to water and various solvents and exhibits strong underwater adhesion on different substrates. Thus, the sensor based on the ionogel exhibits excellent sensing properties, including high sensitivity, fast response, and superior durability. In particular, the ionogel can be used as a wearable underwater sensor to perform barrier-free information transfer. This study provides a design idea for the development of underwater flexible strain sensors.