| Conducting polymer is a kind of highly conjugated structural polymer, of which the conductivity ranges from10-9S/cm (insulation level) to105S/cm (metal level) after chemical, electrochemical or ion doping, the resulted composite materials were tested to have excellent performances were supposed to have a bright application prospective in capacitors, energy, metal corrosion and biosensors.Polythiophene have caused the attention of researchers because of its excellent optical, electrical and environmental stability. Organic/inorganic nanocomposites formed by complexing polythiophene with inorganic nanocomposite material,which was found with improved performance by the introduction of inorganics, and at the same time to which nano effect and synergy effects lead superior performance over simple addition of single component performances. Montmorillonite is a typical nano-layered material, of which the stinted layered space can contribute to ordered conductive polymer polymerization, so as to improve the conductivity of the material. Unsubsituted polythiophene poor solubility and low conversion rates in water, and more research was conducted in organic solvent (CH3Cl, etc.) for damage to the environment,In this paper, polythiophene-montmorillonite (PTP-MMT) and polythiophene-organic montmorillonite (PTP-OMMT) composites were successfully prepared via Fe3+-H2O2catalytic oxidation system at room temperature from water (medium) and sodium dodecyl benzene sulfonate. The prepared PTP-MMT and PTP-OMMT were modified with aniline (ANI) and pyrrole (PY) under Fe3+-H2O2and ammonium persulfate (APS) oxidation systems. Finally, metal anti-corrosion coating were made by the prepared composite materials with epoxy resin and polyamide. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric instrument (TG), scanning electron microscopy (SEM) and four probes were used to characterize the structure, thermal stability, morphology and conductivity of the materials, electro-chemical impedance spectroscopy (EIS) and Tafel (Tafel) polarization curves were investigated corrosion resistance of the coating. The results showed that:(1) XRD and FTIR confirmed an intercalation compounding when thiophene was added to MMT and OMMT, the interlayer of montmorillonite microenvironment was changed for thiophene shaped into the interlayer of montmorillonite, showing hydrophobicity, TG revealed the composite materials have a better thermal stability than polythiophene.(2) With the increase of the amount of montmorillonite, reaction time and amount of the dopant, the conductivity of the composite material showed a decreasing trend after the first increase, but with the increase of the reaction temperature, the conduct-ivity of composite materials continued to decline. When the mass volume of montmorillonite and thiophene ratio was2g/ml, the reaction temperature was20℃, PTP-MMT reached its maximum conductivity of2.12×10-5S/cm during14h, PTP-OMMT having a maximum conduct-ivity of3.44x10-5S/cm at12h.(3)After doped by post-toluene sulfonic acid, the conductivity of the composite increased by nearly two orders of magnitude, n (TSA):n (TP)=0.375and0.625, PTP-MMT and PTP-OMMT achieved its maximum, as2.01×10-3S/cm and3.014x10-3S/cm respectively.(4) When PANI and PPY were modified PTP-MMT and PTP-OMMT, in the Fe3+-H2O2oxidizing system, the products were spherical in shape, arranged in neat; while under the APS system, the products of poor crystallinity, showing no fixed pattern. In both oxidation systems, products had decreased thermal stability, products’thermal stability worst when PPY modified.(5) When PTP-(O)MMT modified by PANI and PPY, the initial products’ conductivity were in a high level in the APS system, with reaction time increased, the conductivity of the products ascend is small; while in the Fe3+-H2O2oxidation system, in an initial conductivity of the products much smaller than APS system, then the conductivity rapidly increase, continue elongation reaction time, the conductivity was no longer increasing. With the amount of PANI and PPY increase, the conductivity of products presented a "△-shaped" variation trend, the products had a maximum conductivity when the dosage of PANI and PPY2times of PTP-(O)MMT.(6) The products which modified with epoxy resin (EP) composite membrane, purity steel sheet after coating, the corrosion potential increases, and the corrosion current is reduced. The coatings corrosion resistance by EIS and Tafel test as follows: Pure Steel sheet<epoxy coating<polythiophene-(organic) montmorillonite/epoxy coating<polyaniline (polypyrrole)-(polythiophene-montmorillonite)/epoxy coating. Polyaniline-(polythiophene-organic montmorillonite)/epoxy coating’s anticorrosion was the best, the corrosion potential highest,-0.576V, and the corrosion current lowest,10-7.752A/cm2. |
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