A ceramifiable organic-inorganic fire extinguishing hybrid coating capable of cyclic fire-warning

•A fire-retardant fire-alarm GTi@GMP coating has been prepared.•GTi@GMP coating shows good ceramic charring capability.•150-μm-thick coating enables RPUF to reach a UL-94 V0 rating and 77% CO reduction.•RPUF@GTi@GMP shows a rapid fire-alarm response and a cyclic warning performance.•GTi@GMP improves compressive strength and maintains thermal insulation of RPUF. Lightweight and thermally insulating rigid polyurethane foam (RPUF) features various important industrial applications, but intrinsic flammability extremely restricts its practical use. The development of multifunctional coating that combines traditional passive fire retardancy and active fire alarm response has been proven to be a promising method to improve the fire safety of RPUF. Herein, we rationally construct organic-inorganic hybrid coatings with a flame-retardant layer and a temperature-sensitive layer by using poly (vinyl alcohol) (PVA), TiO2, graphite nanoplates (GNs), glass powders (GPs), and copper phytate modified mica (MP) as building blocks. The resultant RPUF achieves a V-0 rating during vertical burning with a limiting oxygen index of up to 31.5 vol.%, in addition to reduced heat and CO yield by 24.0% and 77.0%. Moreover, the coated foam shows a rapid fire-alarm response of ∼8 s upon flame attack and displays a good fire cyclic warning performance. Furthermore, the thermal insulation property is well-preserved even when exposed to ∼1100 °C flame due to the good ceramic charring capability. This work provides a promising strategy for the creation of fire-proof coatings for RPUF, which hold great promise for many industrial applications.