Papers by Keyword: Polypyrrole

Abstract: Crown ether 18C6 was used as a phase transfer catalyst (PTC) for the interfacial polymerization of polypyrrole (PPy). Usually, in interfacial reacting system, oxidant FeCl₃ was dissolved in deionized water to form aqueous phase, while pyrrole was dissolved in chloroform to form organic phase. The 18C6 PTC can efficiently form complexes with Fe (III) and transfer Fe (III) from aqueous phase into organic phase, resulting in nanoscale hollow-bubbly PPy with better electronic properties. UV-vis was used to confirm the phase transfer ability of composed Fe (III). Cyclic Voltammograms (CVs) were used to characterize capacitance property of PPy. Fourier Transition Infrared (FT-IR) spectroscopy and Scanning Electronic Microscopy (SEM) were carried out to investigate the microstructure of PPy. Finally, defect control migration growth mechanism of PPy during the polymerization has been carefully discussed.

Abstract: Conductive polypyrrole (PPY) was successfully synthesized via situ polymerization of pyrrole monomer in presence of nanocrystalline cellulose (NCC) suspension as a dopant and template with a rarity sedimentation. PPY-NCC composite having very good dispersion stability in aqueous media. The chemical structure of PPY and PPY-NCC was investigated by using Fourier transform infrared spectroscopy. FTIR result shows that the synthesis of PPY in presence of NCC still retains its chemical structures well. Scanning electron microscopy (SEM) analyses shows obvious transformation in PPY morphology from cauliflower-like spherical particles with 400-500 nm to nanofibers with 200nm length after composite with NCC. Transmission electron microscopy (TEM) revealed the typical morphology of NCC rod-like nanostructure with length 150 ±23 nm and diameter 6.5 ±0.68 nm and the NCC nanorod is coated by a cover of PPY with irregular thickness.

Abstract: Lysine doped polypeptide modified particles were chemically synthesized in different weight ratios of polypeptide to Py feed. The microstructures of these PPys were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR). Semiconductor parameter analyzer, ubbelohde viscometer and rotation viscometer were used to characterize the electrical property, viscosity and solubility of these PPys. The results show that the polypeptide has the function as the template in the Py polymerization. The lysine doped PPys form many rings with diameters of about several micrometers, with the weight ratio increase, the ring structure become more obvious and the diameters of the rings decrease to about 200 nm. The conductivity of lysine doped polypeptide modified PPys synthesized with the weight ratio of 3:1 is about 1.73 × 10^-3 S/cm. It is mostly soluble in acetic acid, good soluble in the mixture of acetic acid and HFIP with a volume ratio of 2:1. Moreover, the solubility in the mixture of acetic acid and HFIP is little affected by weight ratio and maintain about 93.8%, indicating its good solubility in no toxicity solvent or very low toxicity solvent.

Abstract: 4-(3-(Pyrrol-1-yl) butyric acid base)-2,2,6,6-tetramethylpiperidin (Py-B-TEMPO) was synthesized by etherification reaction of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-yloxy. And the polymer of its monomer was prepared by chemical oxidative polymerization and the chemical structure and battery performance of the prepared materials were characterized comparably by Mass spectrometry, ¹H NMR, FT-IR spectra and galvanostatic charge-discharge testing using simulant lithium ion half-cell method, respectively. The results shows that the introduction of the TEMPO group to the pyrrole could prevent the polymer from agglomeration and optimize the particle morphology of the resulting polymers, all of which made it demonstrate a significantly improved specific capacity of 86.5 mAh·g^-1 (99% of the theoretical capacity) compared with PPy (21.7 mAh·g^-1). Moreover, it gives an obvious voltage plateau of nearly 3.5 V which is comparable to the redox potential of TEMPO.

Abstract: The novel magnetic nanocomposites have been prepared by simultaneous forming of Fe₃O₄ nanospheres and graphene sheets in an anchoring mode and polymerizing of pyrrole on the Fe₃O₄ surface. TEM, XRD and XPS were used to characterize the as-prepared products. Nanocomposites exhibit excellent adsorption capability of 348.4 mg g^-1 for heavy metal Cr (VI) ions, and moreover, are stable, separable easily under external magnetic field and recyclable, retaining about 83.1% of the removal efficiency after four adsorption-desorption cycles. The adsorption isotherm has been studied and shows a good consistency with the Langmuir mode. The nanocomposites could be a good candidate for efficient removal of Cr (VI) from the wastewater.

Abstract: Bacterial cellulose (BC) /Polypyrrole (PPy) /TiO₂ composite membrane was successfully prepared by in situ chemical oxidation polymerization of pyrrole in TiO₂ sol into BC membrane matrix with different concentration of TiO₂. The results of the field emission scanning electron microscopy observation revealed that the TiO₂ nanoparticles coated with PPy were well homogeneously dispersed in the BC matrix. The photocatalytic activity of composite membrane was measured by methyl orange reaction model. Furthermore, the chemical structure of composite membrane and the anatase-TiO₂ crystal structure were characterized by FT-IR spectroscopy and XRD analysis, respectively. According to this study, the photocatalytic activity of composite membranes was improved significantly by the addition of TiO₂ due to the synergistic reaction between TiO₂ and PPy. Besides that, the membrane exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to prepare the BC /PPy /TiO₂ composite membrane which would have potential applications in wastewater treatment.

Abstract: A simple oxidative polymerization of pyrrole (Py) directly onto the surface of iron (Fe) microparticles was applied to increase the content of carbon in resulting material. Detection and quantification of the PPy (polypyrrole) coatings obtained were performed by means of pyrolysis gas chromatography (Py-GC). A powder consisting of such particles was compacted. The effect of PPy coating on the compressibility of coated iron powder was analysed. Namely, a set of specimens was uniaxially pressed in a steel die. Compaction pressures ranged from 50 MPa up to 600 MPa. It was found that PPy coating has a positive effect on the compaction behaviour of iron powders in the low to moderate pressure region. At higher pressures, the brittleness of PPy coating adversely affected the compressibility. Both the light and the scanning electron microscopy (LM, SEM) were used to characterize the morphology of coated powders and the microstructure of pressed samples.

Abstract: Functional floating bead (F-FB), prepared by anchoring the organic sulfonic acid on the surface of the blackberry-like structural FB, was used as both the inorganic substrate and the in situ dopant for the in situ chemical oxidative polymerization of pyrrole to obtain the polypyrrole/functional floating bead (PPy/F-FB) composites. The encapsulating morphologies were revealed with the scanning electron microscopy technique. The PPy/F-FB composites were characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. Based on the cyclic voltammetry of the composites, it was found that the composites performed typical electrochemical supercapacitor behavior.

Abstract: Functional floating bead (F-FB), prepared by anchoring the organic sulfonic acid on the surface of the blackberry-like structural FB, was used as both the inorganic substrate and the in situ dopant for the in situ chemical oxidative polymerization of pyrrole to obtain the plypyrrole/functional floating bead (PPy/F-FB) nanocomposite material. The composites possess high electrical conductivity at room temperature. Thermogravimetric analysis shows that the thermal stability of PPy/F-FB composites was enhanced and these can be attributed to the retardation effect of sulfonic acid-functionalized FB as barriers for the degradation of PPy. The morphology of PPy/FB composites showed the well-defined blackberry-like morphology.

Abstract: Polypyrrole/Graphene oxide composite material (PPy/GO) was synthesized using an in-situ chemical polymerization method. The formation of composite had been shown by the analysis of Fourier transfer of infrared spectroscopy and X-ray diffraction data. Scanning electron and transmission electron microscopy clearly showed sheet-like layered structure of graphite oxide surrounded by polypyrrole. Electrochemical properties were characterized by electrochemical station. We demonstrated the intercalation of conducting polypyrrole into the graphite sheets, and that as electrodes for supercapacitor, the PPy/GO composites (GO_0.54) with PPy to GO mass ratio of 5:3 showed a competitive capacitance of 337 F g^-1 at a scan rate of 2 mV s^-1 than that of PPy alone. Given the electrical and electrochemical properties, we prospect that the PPy/GO composites should find applications in supercapacitors.