Biomimetic, mechanically strong and sensitive cyclic fire warning sensor based on high-concentration exfoliated MoS2 and poly-p-phenylene benzobisoxazole film

Abstract

The design and development of fire alarm sensors (FAS) with early fire warning and flame-retardant functions are significant in monitoring critical fire risks of combustible material. However, FAS with high flexibility, strength, environmental resistance, high temperature resistance, and sensitive fire detection still face challenges. In this work, we report a green and simple tannic acid-assisted mechanical exfoliation method to prepare few-layer modified molybdenum disulfide (TA-MoS₂) nanosheets, which exhibit good dispersibility in water and polar organic solvents. Subsequently, the sol-gel and low-temperature self-assembly methods were used to prepare biomimetic TA-MoS₂/p-phenylene benzobisoxazole (PBO) films with a biomimetic nacre structure. The films exhibit excellent flexibility and strength, with a tensile strength of 177.9 MPa. Besides, the films can maintain good integrity after folding and ultrasonic treatment. In addition, the film has excellent flame retardancy and can maintain good structural and dimensional stability under long-term (>500 s) flame attack. More importantly, TA-MoS₂/PBO films show sensitive reversible fire alarm response when attacked by fire and can repeat the warning with a super-fast recovery time (<0.5 s). After multiple flame attacks, it can achieve long-lasting alarm (>1200 s). Even after simulated complex environmental treatment, it can maintain good mechanical performance and warning effect and adapt to complex outdoor conditions. Therefore, this work provides a new approach for preparing high-strength flexible cyclic sensitive warning sensors.