The Research On Template Synthesis Of Polypyrrole And Its Composites By Vapor-Liquor Phase Polymerization

Polypyrrole(PPy) has been widely studied among conductive polymers because of its good environmental stability and high electrical conductivity.The PPy with special structure might have special application due to its highly ordered morphology. Therefore,the study on the PPy with special morphology is meaningful to scientific research as well as industrial application.In this paper,vapor-liquor phase polymerization was adopted for controlling the polymerization reaction at a reasonable speed.And several templates with different properties were used for synthesizing different morphological PPy and its composites. The molecular structure,morphology,electrical properties and other properties of the products were also characterized and analyzed in this dissertation.For the synthesis of PPy,FeCl₃ was used as oxidant and dopant in aqueous medium,which was kept at 0℃.The pyrrole monomer entered in the FeCl₃ solution from vapor phase,and then the polymerization reaction took place.The optimum polymerization time was 6h by comparing the conductivity of the products.When the molar ratio of FeCl₃:Py was fixed at 2.3:1,DBSNa/AOT/TSNa was added separately as the second dopant(FeCl₃:DBSNa/AOT/TSNa=5:1).The results showed that the PPy prepared by FeCl₃-DBSNa showed better performance in conductivity and thermal stability.Furthermore,the conductivity of polypyrrole increased with higher usage of DBSNa(FeCl₃:DBSNa=25:1,15:1,5:1),while their morphology also changed.The nano/micro wire from the self-assembling of 2-anthracen-9-ylmethylene malononitrile(AYM)in ethanol-water solution was used as hard template to prepare PPy and AYM composite.The vapor-liquor phase polymerization was also employed while FeCl₃ was used as oxidant and dopant.Tubular PPy could be easily obtained by removing AYM template when the PPy and AYM composite were dissolved in CH₂Cl₂.The infrared spectrum(ATR) of the composite mainly exhibited the characteristic adsorption peaks of PPy,which indicated that the AYM template was covered by PPy.It was also found when the pyrrole usage was too low,PPy could not cover the whole AYM template to form continuous nano/micro tube;when the pyrrole usage was too high.a lot of spherical PPy granules,which was similar to the PPy prepared by bulk polymerization,could be observed around the PPy tubes.The montmorillonite/polypyrrole(MMT/PPy) composites were also prepared by vapor-liquor phase polymerization with MMT as hard template.Before polymerization,the MMT was dispersed in aqueous solution of oxidant and dopant for ionic exchange of Na⁺ with Fe³⁺.XRD patterns showed that the interlayer space was increased with higher PPy content.Flake-like MMT/PPy structures were observed by SEM,especially when DBSNa was used as the second dopant.Even after etching the MMT from the composites,the remnant PPy could still kept flake-like morphology.This indicated that the growing and packing of polypyrrole macro molecular within confined space was very different from that in free space of solution. This special assembling of PPy leaded to the higher conductivity of MMT/PPy composite than bulk PPy when PPy content was about 50%.The MMT/PPy composites prepared with FeCl₃-DBSNa exhibited higher conductivity and better thermal stability than the composites prepared with FeCl₃ only.The PU-MP compound coating was prepared by mixing the MMT/PPy composite(MP) with polyurethane(PU) varnish.The anti-corrosion test showed that the adding of MP could lead to slight improvement in resistance performance under acidic,saline,salt-frog condition,However,both PU and PU-MP coatings did not exhibit satisfying resistance performance under basic condition.Separated flake-like MP was observed in PU-MP by SEM,while some of them still kept agglomerated.