A Semi-Interpenetrating Poly(Ionic Liquid) Network-Driven Low Hysteresis and Transparent Hydrogel as a Self-Powered Multifunctional Sensor

Conductive hydrogels are gaining significant attention as promising candidates for the fabrication materials for flexible electronics. Nevertheless, improving the tensile properties, hysteresis, durability, adhesion, and electrochemical properties of these hydrogels remains challenging. This work reports the development of a novel semi-interpenetrating network poly(ionic liquid) hydrogel named PATV, via the in situ polymerization of acrylamide, N -[Tris(hydroxymethyl)methyl] acrylamide, and 1-vinyl-3-butylimidazolium tetrafluoroborate. The density functional theory calculations reveal that the poly(ionic liquid) in the hydrogel network acts as physical cross–linking points to construct hydrogen-bond networks. Furthermore, the hydrogen-bond networks dissipate energy efficiently and quickly, and thus stress concentration and hysteresis are avoided. The prepared hydrogel has a low hysteresis (9%), high tensile properties (900%), fast response (180 ms), high sensitivity (gauge factor = 10.4, pressure sensitivity = 0.14 kPa −1 ), and wide sensing range (tensile range: 1–600%, compression range: 0.1–20 kPa). A multifunctional sensor designed based on the designed hydrogel enables real-time, rapid, and stable response-ability for the detection of human movement, facial expression recognition, pronunciation, pulse, handwriting, and Morse code encryption. Furthermore, the assembled triboelectric nanogenerator displays an excellent energy harvesting capability, thus highlighting its potential application in self-powered flexible wearable electronic devices.