Preparation And Characterization Of Polyaniline And Its Nano Composite Fibers

The nano particles, tin oxide(SnO2), were synthesized by sol-gel method and hydrothermal method, respectively. SnO2 was characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), and scanning electron microscope(SEM). XRD and FTIR results showed that the structure of SnO2 synthesized by hydrothermal method and sol-gel method was tetragonal rutile. The synthesized products are well crystallized and complete crystal shape. The SEM results showed that SnO2 particles synthesized by sol-gel method were irregular massive particles. However, SnO2 nanoparticles synthesized by hydrothermal method were spherical particles with diameter of 100 nm-200 nm and were well dispersed.Polyaniline doped by acid was synthesized by one-step chemical oxidation method. P-toluene sulfonic acid was utilized as the doping proton acid and ammonium persulfate was utilized as the oxidant. The eigenstate polyaniline was achieved by ammonia removal effect of acid doped polyaniline. The doped polyaniline with different acid concentrations and oxidant concentrations was characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), ultraviolet visible absorption spectra(UV-Vis) and scanning electron microscopy(SEM). The conductivity of polyaniline with different concentrations of oxidant, acid and polyethylene glycol(PEG1000) was also investigated. Results showed that the doped polyaniline had crystal structure, which is composed of 1 μm-2 μm particles. With the increasing concentrations of p-toluene sulfonic acid and ammonium persulfate, flaky particle size showed a decreasing trend. When the molar ratio of aniline and toluene sulfonic acid was 0.5, the molar ratio of aniline and ammonium persulfate was 1 and the molar ratio of ethylene glycol and aniline is 0.02, the highest conductivity of doping polyaniline achieved a maximum level of 0.46 S/cm.The tin oxide / polyaniline composite materials were prepared and characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), ultraviolet visible absorption spectra(UV-Vis) and scanning electron microscopy(SEM). The results showed that tin oxide was successfully doped into polyaniline structure. After the doping of inorganic phase SnO2, microstructure of PANI changed from flake to granular and the final morphology of SnO2/PANI was fibrous. With the decreasing aggregation degree gradually and the enhanced dispersion, the fiber diameter of SnO2/PANI was in the range of 200-300 nm. Single poly aniline sensor and tin oxide / polyaniline composite film sensor was prepared by direct coating method. The sensitivity of different gas ammonia and toluene gas with different composite sensor was tested. Results showed that both polyaniline sensor and tin oxide/polyaniline composite sensor which dosage of tin oxide was 10% had good selectivity to ammonia and toluene gas.