Preparation Of Amino-functional Electrospun Nanofibrous Membrane Sensor And Its Sensing To Nitroaromatics

In this paper,three kinds of electrospun nanofibrous membrane sensors were prepared via electrospinning technique:?Py-PS/GEL?/G electrospun nanofibrous membrane sensor,?PS-NH₂/pyrene?/G-NH₂ electrospun nanofibrous membrane sensor and CBA&PS/G-NH₂ electrospun nanofibrous membrane sensor.Then the prepared of nanofiber sensors were investigated by detecting the nitroaromatic hydrocarbon?NACs?.Py-PS/GEL/G electrospun nanofibrous membrane sensor consists of two layers of nanofibers and glass carrier.The doped polystyrene nanofiber layer as the sensing layer on the top,the gelatin nanofiber layer in the middle,and the bottom layer was the glass carrier which look like a“Hamburger”.The morphology of the sensor was clearly observed by SEM.The polystyrene nanofibers doped with fluorescent molecular pyrene exhibit a bead structure with a small amount of spindle.And its fiber diameter was much smaller than that of gelatin nanofibers.The Py-PS/GEL/G fluorescent sensor displayed a higher quenching efficiency?67.4%?than Py-PS/G sensor?38.2%?towards DNT vapor with an exposure time of 180 s at room temperature.In order to improve the quenching efficiency of Py-PS/GEL/G sensors for nitroaromatics.A large number of electron-rich amino groups were introduced by adding a nanofibrous membrane gelatin layer.the gelatin layer had the function of enriching NACs by forming a charge-transfer complex between electron-rich amino groups and NACs or attracting each other by hydrogen bonding on the surface of the sensor.And the large pore size of the gelatin fibers was more favorable for the diffusion of NACs.In the electrospinning membrane fluorescence sensor,two measures were used in the sensor to introduce electron-rich amino groups,the first is electron-rich amino grafted on the glass surface which used as the carrier of the sensor,and then the successful preparation of G-NH₂ was determined by XPS,water contact angle test;the second was to graft amino groups to the polystyrene nanofibers directly.The polystyrene nanofibers doped with fluorescent molecular pyrene as the sensing layer.And the morphology of nanofiber sensor can be better observed by SEM image.The?PS-NH₂/pyrene?/G-NH₂ fluorescent sensor showed highly fluorescence stability in ambient condition and further displayed a high quenching efficiency of 65.4%towards trinitrotoluene?TNT?vapor?¹0 ppb?with an exposure time of 150 s at room temperature.In addition,fluorescence images of four sensors(?PS/pyrene?/G,?PS/pyrene?/G-NH₂,?PS-NH₂/pyrene?/G and?PS-NH₂/pyrene?/G-NH₂ sensor)before and after being exposed to TNT vapor were tested.And compared to these sensors,the?PS-NH₂/pyrene?/G-NH₂ sensor exhibited very good sensitivity towards TNT which was may caused by forming charge transfer complexes or hydrogen-bonding between amino group and electron-deficient NACs.The fluorescent compound in CBA&PS/G-NH₂ electrospun nanofibrous membrane sensor was 5-?N-carbazole styryl?-1,3-dimethyl barbituric acid?CBA?with AIE active.CBA compounds had strong fluorescence in solid state,and this could effectively avoid self-quenching phenomenon by?-?accumulation.CBA&PS/G-NH₂ electrospun nanofibrous membrane sensor was used to detect the NACs in the water which show better sensitivity.The quenching efficiency of CBA&PS/G-NH₂ sensor was 81.83%when the concentration of PA was 1.78×10^-4 mol/L,while that of CBA&PS/G sensor was 64.45%.