Synthesis And Characterization Of Polyaniline Micro/nano Structure And Its Composites

In this article, polyaniline (PAn) micro/nanostructures were successfully prepared by self-assembly and soft-template synthesis methods. The formation mechanism and factors on structure and properties of polyaniline were investigated; Bi₂S₃/PAn composites were synthesized by a reverse microemulsion method, and discussed the preparation conditions of Bi₂S₃, characterized the structure and properties of the Bi₂S₃/PAn composites. The main results are as follows:1. The self-assembled micro/nanostructure of polyaniline was controllably obtained by liquid-phase redox reaction in the presence of trifluoroacetic acid(TFA)as the dopant, ammonium persulfate (APS) or FeCl3 as oxidants. The morphology of TFA-doped PAn was affected by the type of oxidants, molar ratio of the trifluoroacetic acid (TFA) to aniline (An)([TFA]/[An]) and polarity of sovents. In water, the morphology of TFA-doped polyaniline was granular when the molar ratio of [TFA]/[An] was higher than or equal to 1, while they turned into hollow micro/nanotubes with the inner diameter from 30 nm to 80 nm and the outer diameter from 200 nm to 300 nm as the molar ratio of [TFA]/[An] was changed to 0.5 or 0.25. The structure of PAn in a doping state can be changed by adjusting pH in solution. The X-ray diffraction experiments suggested that PAn was partly crystal. And its conductivity was 10-3S/cm. Dielectric test results showed that polyaniline had a high dielectric constant and dielectric loss.2. Polyaniline micro/nanofibers with azo groups were successfully prepared by polymerization reaction on the complex template(AOⅡ-FeCl3). The concentration of AOⅡ, the addition of inorganic salts, and reaction temperature had certain influence on the morphology of polyaniline. When reaction system contained 6 mM AOⅡand 1.0 M NaCl at room temperature, the resulting PAn revealed absolute micro/nanofibers with the diameter of about 100nm and the length of several microns. Furthermore, their diameter increased (about 150nm) when polymerization reaction took place under low temperature (0⁵℃). FTIR and UV-vis results showed that AOⅡhad been doped into the polyaniline chain. The X-ray diffraction experiments suggested that the micro/nanofibers of polyaniline were partly crystal, and had good thermal stability. The conductivity of PAn was about 10-1S/cm.3. Bi₂S₃ nano-sheets and Bi₂S₃/PAn nanocomposites were synthesized by a reverse micelle method at room temperature. The diameter of Bi₂S₃ nano-sheets increased with the water contentω(ω=[H2O]/[surfactant]) increasing. The crystalline of Bi₂S₃ was well and specified as orthorhombic phase (a=11.14982nm, b=11.38765nm, c=3.94959nm). Bi₂S₃ and Bi₂S₃/PAn materials had good thermal stability and the thermal weight loss rate was 6.4% and 45% at 800℃under N2 atmosphere, respectively. Photodegradation efficiency of Bi₂S₃/PAn with RhB, MB and MO reached 94.1%, 90.1% and 88.6%, respectively, which showed better photo catalytic properties than PAn.