Gas Sensitive Materials Based On Conductive Polymer Nanocomposites Prepared By Electrospinning And Their Gas Sensing Properties

Two types of gas sensitive materials based on conductive polymer nanofibers composites,polyaniline(PANI)/poly(methyl methacrylate)(PMMA)and polypyrrole (PPy)/poly(vinylidene fluoride)(PVdF),were designed and prepared,and characterized by UV-Vis,FT-IR,SEM and Raman spectroscopy.Resistive-type gas sensors based on the composites were constructed combining by the method of electrospinning(ES)with solution in-situ polymerization and vapor polymerization. Their gas sensing properties towards triethylamine(TEA)and NH₃ have been investigated at room temperature.The effects of ES parameters and polymerization conditions were discussed,and the sensing mechanism was explored.Gas sensors based on PANI/PMMA nanofibers composite were fabricated by ES and solution in-situ polymerization.The electrical responses of the sensors towards TEA vapors ranging from 20 to 500ppm were investigated at room temperature.The sensor exhibited high sensitivity and good reproducibility,and the sensing magnitude was as high as 77 towards 500ppm TEA vapor.Moreover,the sensitivity increased with decrease in fiber diameter.The effects of ES time,nature and concentration of doping acid on gas sensor were investigated.It was found that deposition time and concentration of the doping acid did not affect the sensing properties.In contrast,the nature of doping acid was determinative for the sensitivity and the sensor with p-toluene sulfonic acid as doping acid exhibited the highest sensing magnitude.In addition,a mechanism was proposed by taking account into interaction of doping acids with TEA vapor.Gas sensors based on PPy/PVdF nanofibers composite was prepared by ES and vapor polymerization.The electrical responses of the sensors towards NH₃ ranging from 550-4400ppm were investigated at room temperature.The sensors exhibited fast, highly sensitive,reversible and reproducible responses towards NH₃.It's sensitivity is much higher than that of sensor based on PPy/PVdF thin film.Furthermore,the effects of concentration of polymer solution,polymerization time and polymerization temperature on their sensitive properties were investigated,and the sensing mechanism was explored.