Ag/polypyrrole (PPy) core‐shell nanospheres were fabricated through the redox reaction between pyrrole monomer and silver nitrate in the presence of polyvinylpyrrolidone (PVP) and by using the Ag colloidal nanoparticles acting as the seedings. The prepared nanospheres with a shell thickness of 10–12 nm and a core diameter of 20–40 nm are uniform in size and well dispersed. The morphologies, compositions, and electrochemical activities of Ag/PPy composites were characterized by TEM, XRD, FTIR, TGA and CV. The synthetic route employed here is gentle and can be extended to prepare other conducting polymer/inorganic nanocomposites. 相似文献
The electrochemical modification of activated carbons (AC) by a conducting polymer polypyrrole (PPy) has a substantial effect on the AC structure characteristics, electrochemical properties, and adsorption activity with respect to natural substances (by the example of free hemoglobin). Using the method of standard contact porosimetry (SCP), the porous structure and hydrophilic–hydrophobic properties are studied for the activated carbon SKT-6A, the [SKT-6A/PPy/Cl–] composite, and individual polypyrrole. The chemistry of the activated carbon surface is studied by the standardized Boehm method. It is shown that the nature of activated carbon and its initial surface substantially affect the character of its interaction with the conducting polymer polypyrrole. The effect of such modification on the AC surface chemistry should be considered in aggregate by taking into account each component of such modification. The increase in the sorption ability of [AC/PPy/Cl–] composites with respect to hemoglobin is largely associated with the stronger hydrophilicity of polypyrrole as compared with activated carbons. 相似文献
A facile gas phase polymerization method has been proposed in this work to fabricate porous free-standing polypyrrole (PPy) films. In the presence of pyrrole vapor, the films are obtained in the gas/water interface spontaneously through the interface polymerization with the oxidant of FeCl(3) in the water. Both the thickness of the film and the size of the pores could be controlled by adjusting the concentrations of the oxidant and the reaction time. The as-prepared PPy films exhibited a superhydrophilic behavior due to its composition and porous structures. We have demonstrated a possible formation mechanism for the porous free-standing PPy films. This gas phase polymerization is shown to be readily scalable to prepare large area of PPy films. 相似文献
The synthesis of supramolecular conducting nanowires can be achieved by using DNA and pyrrole. Oxidation of pyrrole in DNA-containing solutions yields a material that contains both the cationic polypyrrole (PPy) and the anionic DNA polymers. Intimate interaction of the two polymer chains in the self-assembled nanowires is indicated by FTIR spectroscopy. AFM imaging shows individual nanowires to be continuous, approximately 5 nm high and conformationally flexible. This feature allows them to be aligned by molecular combing in a similar manner to bare DNA and provides a convenient method for fabricating a simple electrical device by stretching DNA/PPy strands across an electrode gap. Current-voltage measurements confirm that the nanowires are conducting, with values typical for a polypyrrole-based material. In contrast to polymerisation of pyrrole on a DNA template in bulk solution, attempts to form similar wires by polymerisation at surface-immobilised DNA do not give a continuous coverage; instead, a beads-on-a-string appearance is observed suggesting that immobilisation inhibits the assembly process. 相似文献
Polystyrene/polypyrrole (PS/PPy) core–shell nanocomposite particles with uniform and tailored morphology have been successfully synthesized using the “naked” PS particulate substrate with the aid of a proposed strategy, the so-called swelling–diffusion–interfacial polymerization method. After initially forming pyrrole-swollen PS particles, diffusion of the monomer toward the aqueous phase was controlled through the addition of hydrochloric acid, eventually leading to its polymerization on the substrate particle surface. This process allows the nanocomposite particles to possess uniform and intact PPy overlayer and affords much more effective control over the structure and morphology of the resultant nanocomposites by simply changing the PS/pyrrole weight ratio or the addition amount of the doping acid. In particular, the nanocomposite particles with a thin, uniform, and intact PPy overlayer and their corresponding PPy hollow particles were obtained at a low addition amount of pyrrole. The resultant nanocomposite particles have been extensively characterized using scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetry. 相似文献
Summary: Polypyrrole is one of the most widely‐studied conducting polymers due to its steady electrochemical response and good chemical stability in different solvents, including organic and inorganic ones. In this work, we provide for the first time valuable information in atomic detail concerning the steady and dynamic properties of pyrrole rings as a function of the oxidation state of the polymer. The study was carried out by Classical molecular dynamics simulation, where the system was modelled by 256 polypyrrole chains of 10 pyrrole rings each. Water was explicitly introduced in our simulations. Besides the uncharged or reduced state, two steady oxidation states of the polymer have been simulated by introducing a net charge (+1) on 85 and 256 of the polypyrrole chains. To balance the charges emerging in these oxidised states, 85 and 256 chloride ions (Cl−1) respectively, were introduced into the system. From an analysis of the simulated trajectories, the orientation and relaxation times of water and pyrrole rings were evaluated for the different oxidation states of the polymer across the polypyrrole/water interface. The calculated densities for different oxidation states describe the swelling or shrinking process during electrochemical oxidation or reduction respectively. The rotational relaxation times calculated for the polypyrrole rings decrease with increasing oxidation of the polymer, which is in a good agreement with experimental electrochemical data. Almost no variation in pyrrole ring orientation was measured for the different oxidation states of the polymer, even compared with polypyrrole bulk. As regards the water structure in the vicinity of the polypyrrole/water interface, both the orientation and orientation relaxation time were strongly affected by the presence of charges in the polymer. Thus, the water dipole was strongly orientated in the vicinity of the water/polypyrrole interface and its orientational relaxation time increased by one order of magnitude compared with bulk water, even when only one‐third of the total polymer chains were oxidised. The results attained in this work were validated with experimental results, when they were available.
Polypyrrole ring orientation and water orientation at the polypyrrole/water interface. (a) 256 rPPy and (b)171 rPPy + 85 oPPy. 相似文献
Conducting polymer is an important electrode material for supercapacitors because of its high initial specific capacitance. Herein, a novel nanocomposite composed of polypyrrole (PPy) film homogeneously immobilized on the pillar[5]arene functionalized reduced graphene oxide nanosheets (RGO-HP5A-PPy) was successfully prepared. RGO-HP5A induced pyrrole to polymerize on the graphene surface and the specific capacitance loss caused by PPy agglomeration was avoided. Noticeably, the specific capacitance of RGO-HP5A-PPy was up to 495 F/g at 1 A/g. Compared with pure PPy (319 F/g), the specific capacitance was increased by 55%. The specific capacitance retention of the assembled symmetric supercapacitor reached 76% after 10,000 cycles at 5 A/g. This study gave full play to the advantages of pillar[5]arene, graphene and PPy, and was expected to promote the development of supramolecular functionalized composites in energy storage. 相似文献
Experimental and theoretical methods have been used for characterization of the properties of polypyrrole films. The AFM studies show that the morphology of polypyrrole (PPy) films on polycrystalline gold electrodes at the first stages of synthesis depends on the structure of the metal surface. It was established that mobility of anions depends remarkably on the rate of electrodeposition of the polymer film. If PPy film was deposited at relatively low current density, mobility of ClO-4 anion was not high enough to guarantee electroneutrality during redox cycling and cations take part in this process especially when Li+ cations were replaced by more mobile + cations. Semiempirical (AM1 and PM3) quantum-chemical methods were used for theoretical studies. It was established that different size and charge of the anions together with the variation in doping levels give rise to a different optimal conformation of oligopyrrole cations which, in turn, define the resulting polymer to be either all-anti (common linear chains) or all-syn (formation of helical structures) or a combination of the two. 相似文献
A functionalized stable film of poly(pyrrole-sulfated β-cyclodextrin) has been obtained electrochemically in LiClO4 aqueous solution using a simple 1:1 mixture of pyrrole (Py) monomer and sulfated β-cyclodextrin (SβCD). Different cyclic
voltammetric behavior is obtained for polypyrrole (PPy) and poly(Py-βSCD) during electrosynthesis. Scanning electron microscopy
(SEM) and energy dispersive X-ray analysis (EDAX) measurements on the two films have confirmed the presence of CD in the films
and show that CD preferentially dopes the polymer even in the presence of a large excess of perchlorate supporting electrolyte.
The morphology of the new polymers shows a more organized system under SEM examination. Contrary to conventional PPy films,
this new polymer offers a wide potential range for electroanalytical exploration from selective electrodes to preconcentration/sampling
devices.
Electronic Publication 相似文献
Unique nanocomposites of polypyrrole/Au and polypyrrole/Pt hybrid nanotubes are synthesized employing polypyrrole (PPy) nanotubes as an advanced support by solution reduction. The conducting polymer PPy nanotubes are fabricated by using pre‐prepared MnO2 nanowires as the reactive templates. MnO2 nanowires induce the 1D polymerization of pyrrole monomers and the simultaneous dissolution of the templates affords the hollow tube‐like structure. The loading content of metal nanoparticles in the nanocomposites could be adjusted by simply changing the amount of metal precursors. This work provides an efficient approach to fabricate an important kind of metal/conducting polymer hybrid nanotubes that are potentially useful for electrocatalyst and sensor materials. 相似文献
The electropolymerization of pyrrole on gold modified by a self-assembled monolayer (SAM) of a pyrrolyl lipoic acid derivative
was investigated in detail and the results compared to those obtained on bare substrates. Both under potentiostatic and potentiodynamic
control, a slight blocking action of the underlying SAM could be observed for the initial stages of polymer growth but thereafter
the electrochemical features were similar to those collected for polypyrrole (PPy) deposition on bare gold. The morphology
and structure of PPy films formed on the SAMs were characterized by atomic force microscopy and X-ray diffraction, which revealed
that those polymer properties are much more influenced by the electrochemical mode of preparation, than by the underlying
SAMs. While, when compared to PPy on bare gold, no effect has been detected on thin layers deposited at constant potential,
surface areas with rather irregular morphology, as well as a small but beneficial influence in inducing order on the first
few layers of the polymer film, have been observed on similar films formed by cyclic voltammetry. The typical globular morphology
of PPy has always been observed for relatively thick layers in which the redox behavior, analyzed by in situ AFM, showed an
increase in volume of the polymer nodules upon reduction, largely due to the SAM reorganization induced by the applied potential. 相似文献
Conducting polymer composite films comprised of polypyrrole (PPy) and multiwalled carbon nanotubes (MWCNTs) [PPy–CNT] were synthesized by in situ polymerization of pyrrole on carbon nanotubes in 0.1 M HCl containing (NH4)S2O8 as oxidizing agent over a temperature range of 0–5 °C. Pt nanoparticles are deposited on PPy–CNT composite films by chemical reduction of H2PtCl6 using HCHO as reducing agent at pH = 11 [Pt/PPy–CNT]. The presence of MWCNTs leads to higher activity, which might be due to the increase of electrochemically accessible surface areas, electronic conductivity and easier charge-transfer at polymer/electrolyte interfaces allowing higher dispersion and utilization of the deposited Pt nanoparticles. A comparative investigation was carried out using Pt–Ru nanoparticles decorated PPy–CNT composites. Cyclic voltammetry demonstrated that the synthesized Pt–Ru/PPy–CNT catalysts exhibited higher catalytic activity for methanol oxidation than Pt/PPy–CNT catalyst. Such kinds of Pt and Pt–Ru particles deposited on PPy–CNT composite polymer films exhibit excellent catalytic activity and stability towards methanol oxidation, which indicates that the composite films is more promising support material for fuel cell applications. 相似文献
In-situ polymerization of pyrrole was carried out with strontium arsenate (ceramics) in the existence of oxidizing agent ammonium persulphate to synthesize polypyrrole/strontium arsenate composites by chemical oxidation method. The polypyrrole/strontium arsenate composites were synthesized with various compositions viz., 10 to 50 wt % of strontium arsenate was placed in polypyrrole. The surface morphologies of these composites were analyzed using Scanning Electron Microscopy (SEM) which confirmed the embedment of strontium arsenate particles in PPy chain. The Fourier Transform Infra-Red spectra (FTIR) revealed the shift of lengthens frequencies towards elevated frequency area. The powder X-ray diffraction patterns (XRD) disclosed the crystalline behavior exhibition of the composites. Thermographs of thermal analysis (TG/DTA) exposed the stronger stability of polypyrrole/strontium arsenate composites than PPy. D.C. conductivity reveals that, the strontium arsenate concentration in polypyrrole is accountable for the variant of conductivity of the composites. The results of the study signify the increment of D.C. conductivity for 40 wt % of strontium arsenate in polypyrrole. The temperature reliant conductivity dimension shows the thermally activated exponential behavior of PPy/Sr3(AsO4)2 composites. The reduction in electrical resistance was experienced, when the polymer composites were bare to the wide range of relative humidity (Rh) (from 30 to 95%). This reduce is due to enhance in surface electrical conductivity ensuing from humidity fascination and also due to capillary abridgment of water causing change in conductivity within the sensing materials. The composite shows sensitivity in the range 30 to 95% Rh, we also studied response and recovery time. 相似文献
A surface plasmon resonance (SPR) based biosensor for glucose is presented in which a thin gold film modified with polypyrrole and glucose oxidase (PPy-GOx) acts as the sensor chip. It is based on SPR response to the change of refractive index of PPy-GOx film by the enzymatic catalytic reaction. The co-electropolymerization of pyrrole and GOx was carried out under cyclic voltammetric conditions, and simultaneously monitored by in-situ SPR. It has been revealed that the enzymatic reaction between GOx and PPy in the presence of glucose can lead to distinct changes in the SPR signal. From the experiments, a linear relationship was obtained in the range 1–100 μmol L?1 between glucose concentration and the rate of redox transformation of PPy. The detection limit was 0.5 μmol L?1 (S/N?=?3) and recoveries were 95.2–102.7%. 相似文献
Spiral dislocation morphology on the surface of cetyltrimethylammounium bromide (CTAB) crystallites has been discovered for the first time. By addition of ammonium peroxydisulfate into CTAB crystalline suspension, a drastic change in the morphology of result crystallites is observed from spiral to two dimensional (2D) islands. The spiral and 2D-island structures of these crystallites could be use as the templates for the synthesis of spiral and ring-like polypyrrole (PPy) nanowires, respectively, via direct chemical oxidative polymerization of pyrrole due to the oxidation reaction occurring preferentially at the steps of these crystallites. The mechanism of adsorption of pyrrole oligomers on the steps of these crystallites is proposed for the growth of PPy spiral and ring-like nanowires. 相似文献