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Preparation and Characterization of Pani Ultrafine Composite Fibers

Author: WangXiangQin
Tutor: XuJian;XinBinJie
School:
Course: Fashion Design and Engineering
Keywords: Polyaniline Emulsion polymerization electrospinning ultrafinecomposites fiber the electrochemical property
CLC: TQ342.94
Type: Master's thesis
Year: 2014
Downloads: 7
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Abstract

Polyaniline (PANI), which is a kind of typical conjugated polymer, belongs to the conductive polymer materials. PANI is considered as one of the the most promising functional polymers for the industrialized application prospect due to its good thermal stability, relatively high chemical stability, electrochemical reversibility and the unique doping mechanism. In the recently years, the studies on the PANI composite membrane/fiber mainly prepared by wet spinning and melt spinning have been reported thoroughly, including the doped mechanism of PANI. However, few works on the preparation and characterization of superfine composite fibers prepared by electrospinning have not reported, and the electrochemical properties of them are not yet to be discussed and studied systematically. In this work, the PANI/PVA solution obtained by emulsion polymerization is used for the preparation of the PANI/PVA composite fiber mat.In this paper, PANI/PVA composite emulsion with a certain viscosity and PANI particles in the nanoscale range was prepared by the emulsion polymerization. With the addition of non-ionic surface active agent PVA and the anionic surface active agent DBS A, PANI particles were homogeneously mixed in the emulsion. Through the orthogonal experimental analysis, the effects of three parameters including concentration of proton acid doping, polymerization temperature and oxidant concentration on the emulsion polymerization process of PANI were investigated. In this paper, the experimental results obtained under the experimrental conductions herein, and the importance sequence of these three parameters effected on the conductivity of PANI was:oxidant concentration, proton acid concentration, polymerization temperature; the optimum molar ratio of [DBSA]:[AN]:[APS] was1.03:1:1.PANI/PVA composite liquid emulsion was considered as spinning solution, conducting ultrafine composite nanofibers were fabricated from a mixture of PVA and PANI using an electrospinning process. Surface morphology, thermal properties and crystal of PANI/PVA ultrafine fibers were characterized systematically, the experiment results show that the PANI/PVA ultrafine composite fibers were affected by the PANI content, the tip-target distance and potential.The morphology of PANI/PVA ultrafine composite fibers covering the Aluminum foil were presented in the SEM images. The content of PANI not only affects the diameter of fiber, but also affects the surface morphology of fibers. When the distance of14cm was applied between the solution and the collection screen in the electrospinning experiment, the beads on string structure disappear, the average diameter of the fibers increase, when the distance was further reduced to18cm, the PANI particles can be evenly dispersed. The morphology and distribution of fibers are relatively stable. With the increase of voltage, smooth and continuous PANI/PVA composite fibers with the uniform diameter about578nm could be obtained, and the distribution of diameter can be reduced to144nm.The XRD patterns of PANI/PVA ultrafine composite fibers with different aggregation structure characterizations were shown. It could be observed that the size increasing of PANI particles has an obviously effect on its crystallinity. With the voltage added from14kV to29kV, the crystallinity of PANI/PVA ultrafine composite fibers increases slowly firstly, and then declines sharply. As the tip-target distance of10cm to20cm increases gradually, the crystallinity of the corresponding sample is changed obviously, as the distance set to be18cm, the crystallinity is relatively high. To a certain extent, the content increasing of PANI can improve the heat stability of PANI/PVA ultrafine composite fibers.The CV tests of PANI/PVA composite were studied by electrochemical workstation, it could be found that its electrochromic colour of PANI/PVA composites macroscopically changes from green, blue to yellow in sequences, however, the low temperature polymerization of PANI/PVA composite film is not as well as the specimens at room temperature. From the CV curves, the redox peak at low temperature was not obvious as that at room temperature. With the scan rate ranging from5mV/s to100mV/s, the electrochemical properties of PANI/PVA ultrafine composite fiber mats were characterized. The trend of all curves is consistent, and the redox peak disappeares. The constructions of distribution model of PANI particles in the PVA fibers has been obtained, the effect inferred factors of electrochromic might be the distance between the PANI particles and the fiber direction. The electrochromic layer thickness composed of PANI/PVA ultrafine composite fiber mats was much smaller than the film thickness of PANI/PVE composites artificially prepared, so the color changes of these ultrafine composite fiber mats are exhibited relatively weak.

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