Facile construction of a flexible smart core-sheath flax yarns with temperature-responsive resistance for ultra-fast fire-alarm response

In order to improve the fire safety of combustible materials in daily life, the intelligent sensor with high sensitivity and wireless remote warning ability is urgently needed for early real-time fire detection. Herein, the intelligent core-sheath flax-GO/CS/PDA yarn prepared using the electrostatic interaction between graphene oxide (GO) sheets, chitosan (CS) molecules and polydopamine (PDA). According to the rapid reduction of resistance of GO stimulated at high temperature, it is reduced to reduced GO (rGO), forming a conductive network circuit. Due to the effective protection of the GO/CS/PDA layer on the flax yarn, it prevents the exchange of heat and oxygen, and improves the thermal stability and flame retardant of flax yarn. What's more, in the case of assembling 1 trilayer, the prepared intelligent core-sheath yarns achieve sensitive fire warning response time (∼3 s). The results show that the prepared core-sheath flax-GO/CS/PDA intelligent yarn have excellent flame retardancy and super-fast fire response speed at low temperature (<300 ℃). More importantly, the signal processing information received by the fire alarm device is transmitted to the wireless communication device via Bluetooth. Therefore, when the abnormal temperature is detected, the communication equipment will immediately emit an alarm sound. This study provides a new strategy and foresight for realizing the ideal fire performance and real-time temperature warning response time based on GO, and expands the application of GO network in early fire detection and wireless sensor warning.