Mechanically-robust phosphorus-contained ionogels by UV-curing for fire warning sensor and fire protection

Owing to their superior environmental stability and conductivity, Ionogels have emerged as strong competitors to hydrogels in flexible conductive materials. However, their practical applications are hindered by inadequate mechanical properties. Herein, we report a mechanically robust ionogel synthesized via photo-initiated free radical polymerization of acrylamide (Am) and hydroxyethyl acrylate (HEA) in the ionic liquid 1-butyl-3-methylimidazolium dihydrogen phosphate ([BMIm][DHP]). The resulting Am-co-HEA ionogel exhibits a microphase-separated structure, achieving a maximum tensile strength of 17.41 ± 1.268 MPa. By modulating the content of ionic liquid, the ionogel demonstrates a synergistic enhancement of strength and toughness (tensile strength: 8.11 ± 0.34 MPa, elongation at break: 748 ± 111%) and favorable ionic conductivity (1.19 mS/m), alongside dual responsiveness to mechanical strain and temperature variations. Furthermore, the Am-co-HEA ionogel exhibits enhanced fire safety and can be applied as a flame-retardant and alarm-integrated multifunctional coating on wood surfaces. The ionogel coating enables wooden strips to achieve the UL-94 V-0 rating while elevating the LOI to 31%. Upon flame exposure, the coating rapidly responds to fire threats, thereby significantly improving the fire safety of combustible wood materials.