Graphene oxide/polyethyleneimine/hydroxyapatite nanowire composite paper: Unexpected mechanical robustness after fire attacking and fire alarm application

Recently, graphene oxide (GO)-based fire alarm systems have been well developed due to their rapid response to the flame. However, the GO-based fire alarm systems still suffer from low thermal stability and mechanical fragility in the flame, resulting in a short alarm time and unreliable warning. Herein, we have developed a composite paper composed of polyethyleneimine (PEI)-modified GO and hydroxyapatite (HAP) nanowires. The results demonstrate that PEI molecules are powerful to improve thermal stability and flame retardancy of GO and thus increase alarm time, while HAP nanowires with intrinsic nonflammability act as a stable fire-resistant framework to ensure the structural integrity of the composite paper after fire attacking. As a result, the GO/PEI/HAP composite paper shows the continuous fire warning, and particularly, maintains its mechanical strength mostly and high flexibility after fire attacking. This work provides an instructive guideline to design reliable GO-based fire alarm systems.