Fabrication of an ultralight flame-induced high conductivity hybrid sponge based on poly (vinyl alcohol)/silver nitrate composite

Abstract

In this study, we presented a novel fire alarm device based on poly (vinyl alcohol) (PVA)/silver nitrate (AgNO3) composite embedded in the structural template of melamine (ME) sponge. By using water as a benign solvent, the chelated PVA/AgNO3 hybrid solution was absorbed into ME sponge, and then the ultralight ME monolith containing PVA/AgNO3 was obtained after removing the solvent. When exposed to flame, monodispersive silver nanoparticles (Ag NPs) were synthesized by reducing AgNO3 with PVA. The porous ME sponge acted as a structure-directing template during the in situ reduction process, leading to the controlled formation of a connected network for Ag NPs. Finally, the electrical resistance of the monolith suddenly dropped by 8 orders of magnitude in less than 15s after flaming, which was due to the formation of a conductive path built by the neck formation of Ag NPs. This ultralight conductive monolith based on Ag NPs via flame-induced reduction of AgNO3 could have broad applications in civil, military and aerospace fields.