Fabrication of Polyurea-Based Ionogels for Strain Sensing with High Conductivity, Flame Retardancy, and...

Flexible sensors used under high temperatures and open flames are in high demand in fire rescue and similar scenarios, yet related research remains limited. An intrinsic flame-retardant polyurea-based ionogel with high ionic conductivity and room-temperature self-healing ability is developed in this work. Reactive ionic liquid (IL) containing phosphorus/nitrogen (P/N) flame-retardant groups and dynamic disulfide bonds is covalently incorporated into the polyurea backbone as a chain extender, constructing a dynamic network. The ionic conductivity of the ionogel is as high as 0.169 S/m, with a tensile strength of 2.2 MPa and an elongation at break of 1027%. Meanwhile, 99.5% of the tensile strength is recovered at room temperature after 24 h of self-healing. The polyurea-based ionogel containing P/N groups is intrinsically flame retardant, as evidenced by a limiting oxygen index of 28.8%, a UL-94 V-0 rating, and significantly suppressed heat and smoke release. The flexible strain sensor monitors human motions, even under high temperatures or fire exposure. This work provides a solution for the applications of intelligent sensing devices for fire rescue under high-risk conditions.