| Conductive polymer composite is a kind of polymer materials, the conductivity of which is close to metal or semiconductor, it has features of low density, low production cost, well process-ability, and is widely used in fields such as electronics, energy and biology, etc. Electrospinning technology is a flexible and simple method for preparing polymer nanofibers, the prepared nanofibers are of excellent performances, and have become the research hotspot. Recently, more and more researchers tried to prepare conductive polymer composites by electrospinning method. In this paper, on the basis of already reported work, the methods of electrospinning and chemical-liquid-deposition were combined into a new method for preparing conductive polymer composites with well conductivity and mechanical properties, which overcame the shortcomings of traditional methods effectively. The main contents and results are as follows:(1) Firstly, polyacrylonitrile(PAN) nanofiber membranes were prepared by electrospinning, and they were used as substrates of conductive polymer composites, then a layer of conductive PEDOT was deposited on the surface of PAN nanofiber membranes. Effects of processing conditions(PAN concentration, distance, voltage and drum rotation speed) on the morphology and size of PAN nanofibers were studied, the best result for spinning could obtained with 9.2wt.% PAN, 23 cm spinning distance, 15 kV voltage, and 900r/min rotary speed. The structure and properties of prepared PAN/PEDOT nanofiber membranes were characterized by SEM, FTIR, TGA, mechanical property test and conductivity test. The results showed that, PEDOT polymerized on the surface of PAN successfully and caused the shift of FTIR absorption peaks, the PAN is of good thermal stability, introducing PEDOT decreased the initial decomposition temperature of PAN, improved its maximum decomposition temperature, and reduced the corresponding heat release rate. The breaking strength of PAN/PEDOT nanofiber membranes is 0.5MPa, the conductivity is about 10-2S/cm.(2) In order to improve the dispersibility of carbon nanotubes(CNT) in solvents and polymer matrix, CNT was modified by method of chemical oxidation treatment. Effects of treatment conditions(acidification temperature and time) on the modification degree and damage extent of CNT were studied, and the best result was obtained at 90°C, 2h. The structure and properties of carboxylated CNT were characterized by FTIR, FESEM, TEM, XRD. The results showed that, the acidification treatment did not change the tubular structure of CNT, only produced some carboxyl groups on its surface. Acidification treatment purified CNT and cut off some CNT fibers. The temperature played a more important role in the modification process than time and the thermal stability of CNT decreased with the increase of modification degree.(3) In the third part, the carboxyl treated CNT was added into PAN spinning solution to prepare PAN/CNT composite nanofibers, then PEDOT was deposited on the surface of the nanofibers, and conductive PAN/CNT/PEDOT composite nanofiber membranes were obtained. Effects of CNT content, EDOT concentration, oxidant concentration and oxidation time on mechanical properties and conductivity of PAN/CNT/PEDOT were studied. PAN/CNT/PEDOT membranes with improved conductivity(3.21S/cm) and breaking strength(2.25MPa) were obtained with 20 wt.% CNT content, 2.5% EDOT, 0.3mol/L oxidant concentration, 10 h reaction time. The structure and properties of PAN/CNT/PEDOT composite conductive nanofiber membranes were characterized by SEM, TEM, FTIR and TGA. The results showed that, after introducing CNT, the surface of PAN nanofiber became rough. PEDOT can be successfully polymerized on the surface of PAN/CNT nanofiber membranes, and the thermal stability of PAN/CNT under high temperature was improved. |
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