Fluorescent Triple-Sensitive Fibrous Sensors for Rapid Naked-Eye Identification of Vaporous Nitro-Explosives

Vapor detection of nitro-explosives by fluorescent fibrous film is promising, but practical applications remain constrained by insufficient reliability, particularly in complex and dynamic environments in challenging environments, where extreme weather is exhibited or areas with high temperature and high relative humidity. Significantly, water, a pervasive presence in the air, is a deserving common and variable interferent in industrial, laboratory, and domestic settings. Herein, multifunctional temperature-sensitive fluorescent sensors that can also respond to nitro-explosive and water vapor were reported. They are based on the combinations of poly(N-isopropylacrylamide) (PNIPAM) with 9-(pyren-1-yl)-9H-carbazole (PyCz) and N,N′-dibutyl-3,4,9,10-perylene-tetracarboxylic- diimide (PTCDI). Nitro-explosive vapors can be detected at 50 °C with high sensitivity and selectivity. Moreover, as for 4-NT and TNT, the quenching efficiency reaches 95 and 40% within 1 min. The detection is effective under saturated relative humidity and is not influenced by smoke and aromatic toluene vapors. At 25 °C, the sensor exhibits an obvious response to the explosive compounds in an ambient atmosphere while quenching under a high relative humidity close to 100%. The above changes can be conveniently investigated by the naked eye and tuned by temperature. This work provides a foundation for the future design of molecular responsive multifunctional polymeric fibrous structures for low-cost practical naked-eye vapor sensors.