Efficient flame-retardant and multifunctional conductive flax fabric for intelligent fire protection and human motion monitoring

Highly sensitive intelligent fire-warning sensors with multifunctionality for early fire monitoring are imperative to improve the flammability of flax fabrics in this age of intelligence. Herein, a novel high flame resistance multifunctional intelligent hydrophobic fumed silica/polydopamine/poly(3,4-ethylenedioxithiophene): poly(styrenesulfonate)@graphene oxide@carboxymethyl chitosan@flax fabric (Hf-SiO2/PDA/PGO@CCS@FF) fabric with temperature sensing, fire alarm, piezoresistive sensing and hydrophobic property was prepared via a facile low-temperature evaporation-induced self-assembly method. The obtained Hf-SiO2/PDA/PGO@CCS@FF exhibited excellent and accurate temperature sensing performance benefiting from the high conductivity of poly(3,4-ethylenedioxithiophene): poly(styrenesulfonate) (PEDOT: PSS). When being burned, the fire alarm system could be quickly and repeatedly triggered 3 times in less than 5 s. More importantly, Hf-SiO2/PDA/PGO@CCS@FF showed outstanding flame retardancy to ensure repeated warning. The limiting oxygen index (LOI) of Hf-SiO2/PDA/PGO@CCS@FF was up to 33.6%. After the vertical burning test, Hf-SiO2/PDA/PGO@CCS@FF could self-extinguish and the char length of only 17 mm. Meanwhile, the heat release rate (HRR) and total heat release (THR) of Hf-SiO2/PDA/PGO@CCS@FF reduced by 47.1% and 51.8%, respectively. Using the low surface energy effect of thin Hf-SiO2, the excellent hydrophobic properties was obtained with the water contact angle of 127° and sliding angle of 27°. Besides, the prepared Hf-SiO2/PDA/PGO@CCS@FF fabric was integrated into the fire suit for detecting multiple human motions. The research proposed a simple and facile approach to prepare intelligent early warning temperature sensors for temperature sensing and flame safety, showing attractive prospects in the field of fire proof and temperature detection.