Ultra-stretchable and highly tough ionogels with underwater repeatable adhesion and anti-swelling capacity for real-time motion detection, signal transmission and electrochemical monitoring platforms

Hydrophobic ionogels have received growing interest as a flexible underwater sensing material. However, it remains a significant challenge to improve the tensile properties, prolonged underwater repeatable adhesion, and multifunctionality of the hydrophobic ionogel due to the restricted selection of monomers and curing strategies. Herein, a hydrophobic multifunctional fluorine-rich ionogel with ultra-stretchability and superior long-term underwater repeatable adhesion is designed by virtue of the introduction of a rigid and flexible macromolecular cross-linker and a structure of rigid cationic imidazole-benzene rings in a hydrophobic ionic liquid monomer. The macromolecular cross-linker significantly improves the mechanical properties of the ionogel because of the reduction in stress concentration. And the structure of short imidazole-benzene rings with high rigidity exposes a larger amount of adhesion groups on the surface of the ionogels compared to the flexible groups, leading to enhanced long-term underwater repeatable adhesion performance of the ionogel. The ionogels are applied to real-time monitoring of exposure to water, underwater swimming motion monitoring, underwater Morse code transmission and electrochemical monitoring platforms. And this work is expected to provide ideas for the multifunctionalization of underwater sensing technology and the integration of functional units in underwater flexible electronic skin.