Heparin‐Controlled Growth of Polypyrrole Nanowires

Summary: Heparin, a potent anticoagulant, has been used for the first time for the synthesis of PPy nanowires serving not only as an anion dopant but also as an effective morphology‐directing agent. The obtained PPy nanowires exhibit long and fine structures with smooth surface and the average diameter of the nanowires is about 90–100 nm and lengths are several hundred nanometers to micrometers. The possible formation mechanism of PPy nanowires may be related to the chain structure of heparin with functional groups ( SO and  COO⁻) on the surface. The effect of concentrations of pyrrole monomers and heparin on the morphology and size of PPy nanowires has been investigated.

SEM image of PPy nanowires synthesized in the presence of heparin.     

Conducting Polypyrrole Conical Nanocontainers: Formation Mechanism and Voltage Switchable Property

Nanostructures with stimuli‐responsive properties are of great importance for the application of smart materials in nanotechnology. Unique hollow polypyrrole nanostructured arrays with a conical shape have been produced by a stepwise electropolymerization process. The polypyrrole conical nanocontainers exhibit a reversible switchable behavior between open and closed states, which is controlled by the movement of counter ions during electrically controlled reversible oxidation and reduction processes. The formation of conical nanocontainers is affected by the oleo‐wettability of the substrate. Conical nanocontainers can be formed on oleo‐phobic substrates in aqueous solution by using dopant‐stabilized pyrrole nanodroplets as the guiding template for the polymerization.

     

Optimization of Polypyrrole Chemical Synthesis by Heat Flow Reaction Calorimetry

Chemical polymerization of pyrrole (Py) was carried out in a reaction calorimeter by using FeCl₃ or CuCl₂ as an oxidant in an acetonitrile medium. The formation heat of polypyrrole (PPy), determined under a wide range of reactant concentrations and reaction temperatures, is directly related to the PPy yields and to the degree of polymerization. Due to the negative values of both the entropy and enthalpy of the reaction the gravimetric yield is inversely related to the temperature and directly to the Py concentration. The yields to the PPy and the related reaction heats, are close to zero when the ceiling temperatures are reached (T_ceil=348 K for Fe-doped and T_ceil=313 K for Cu-doped PPys). It was observed that a ceiling concentration corresponds to each ceiling temperature and only light oligomers are formed if Py concentration is too low. The electric conductivity values of the products were also determined and a direct relationship to the yields was found as well. The highest electric conductivity value (C=0.6 S cm^–1) was related to the PPy fresh synthesized from a 0.017 M Py solution.This revised version was published online in November 2005 with corrections to the Cover Date.     

Polypyrrole electrodeposition on inorganic semiconductors CuInSe2 and CuInS2 for photovoltaic applications

Thin polypyrrole (PPy) layers with an average thickness of about 0.5 μm were deposited, using potentiostatic and galvanostatic techniques, on CuInSe₂ (CISe) structures prepared electrochemically on glass/ITO substrates and on CuInS₂ (CIS) structures fabricated on Cu tape substrates. The polymer layer of p-type is considered as an alternative to the traditional buffer layer and window layer in the conventional cell structure. The deposition proceeded from an aqueous solution containing sodium naphthalene-2-sulfonate as a dopant. In order to prepare stable PPy films of high quality with a good adherence to the surface of inorganic semiconductors CIS and CISe, the optimal concentrations of reagents, current densities and electrodepositing potentials were selected experimentally. Electrochemical polymerization of pyrrole to PPy on CIS surfaces is faster under white light irradiation and the polymerisation starts at lower potential than in the dark. Significant photovoltage and photocurrent of the fabricated CISe/PPy and CIS/PPy structures have been observed under standard white light illumination.     

Decorating Polypyrrole Nanotubes with Au Nanoparticles by an In Situ Reduction Process

Au nanoparticle‐decorated polypyrrole nanotubes (defined as PPy/Au nanocomposites) are prepared by an in situ reduction process. Polypyrrole (PPy) nanotubes are prepared by a self‐degraded template method, and Au nanoparticles are deposited in situ by the reduction of HAuCl₄. The size and uniformity of the Au nanoparticles that decorate the PPy nanotubes can be controlled by adjusting the experimental conditions, such as the stabilizers used and the reaction temperature. The morphologies and optical properties of the nanocomposites have been characterized by scanning electron microscopy, transmission electron microscopy, UV‐vis, and FT‐IR spectroscopy. Conductivity measurements show that the conductivities of the nanocomposites decrease with a decrease of temperature, and the conductivity–temperature relationship obeys the quasi‐one dimensional variable range hopping model.

     

Insertion of Polypyrrole Chains into Montmorillonite Galleries by a Solvent‐Free Mechanochemical Route

Summary: Non‐ionic pyrrole was directly intercalated into unmodified montmorillonite (MMT) and organically modified MMT galleries by adsorption, and subsequently polymerized within the interlamellar spaces by a mechanochemical route under solvent‐free conditions. XRD analysis revealed the successful intercalation of pyrrole into unmodified MMT and organically modified MMT clay galleries by mechanochemical grinding. After in situ polymerization, the XRD and FT‐IR analyses confirmed the insertion of polypyrrole chains between both MMT galleries.

X‐ray powder diffraction patterns of (A) pyrrole‐intercalated MMT and (B) pyrrole‐intercalated C18‐MMT.     

Facile Fabrication of Functional Polypyrrole Nanotubes via a Reactive Self‐Degraded Template

Summary: Polypyrrole nanotubes with high electric conductivity and azo function have been fabricated in high yield via an in‐situ polymerization. During the process fibrillar complex of FeCl₃ and methyl orange (MO), acting as a reactive self‐degraded template, directed the growth of polypyrrole on its surface and promoted the assembly into hollow nanotubular structures.

TEM image of uncompleted PPy nanotubes synthesized in MO solutions after reaction for 40 min.     

Synthesis of Specially Designed Adhesion Promoter for Grafting Polypyrrole

Summary: Adhesion of conducting polymers to the metal/metal oxide surfaces is not strong. An attempt was made to modify these reactive metal surfaces by N-derivatised pyrroles. ω-(pyrrol-1-yl alkyl) phosphonic acids with different chain lengths were successfully synthesized and characterized. These derivatives were studied for their adsorption and self-assembling phenomena onto Ti/TiO₂, Ta/Ta₂O₅ and Al/Al₂O₃. Various analytical tools were used to characterize the modified surface. Contact angle measurements indicated an increase in hydrophobicity after adsorption that was further confirmed by Surface Plasmon Resonance (SPR). X-ray Photoelectron Spectroscopy (XPS) studies showed that the molecules are oriented in a fashion such that phosphonic acid group is attached to the metal surface and pyrrole is pointing away from the surface. The oxidation potential of these derivatives was higher than pyrrole as expected. Surface polymerisation was successfully attempted on the modified metal substrates. The polymerised surface was examined under Scanning Electron Microscope (SEM). The new compounds not only function as self-assembling molecules, they also exhibit a new class of reactive functionalized derivatives that can be used as monomers for polymerisation.     

聚吡咯纳米线(管)的合成

聚吡咯纳米线(管)是一种极具应用潜力的新材料.本文综述了聚吡咯纳米线(管)的各种合成方法.并对各方法的优缺点进行了评述.     

Synthesis and in situ doping of highly conductive polypyrrole nanocomplexes with binary acids

The synthesis of doped polypyrrole (PPy) nanocomplexes and their size, morphology, doping level, and electrical conductivity are discussed. The synthetic route of doped PPy nanocomplexes is presented by means of the chemical oxidative polymerization and in situ doping process in the presence of a binary acid mixture (hydrochloric acid and perchloric acid). The electrical conductivities of the doped PPy nanocomplexes are enhanced from 0.88 to 4.5 S/cm by the optimum molar ratio of HClO₄ and HCl in the binary acid mixture. In addition, the average particle size of the doped PPy nanocomplexes decreases from 280 to 30 nm with a narrow particle size distribution when increasing the proportion of HClO₄ relative to HCl in the binary acid mixture; this result is confirmed by scanning electron microscopy, transmission electron microscopy, and capillary hydrodynamic fractionation instrument analyses. Moreover, at different molar ratios in the binary acid mixture, the zeta‐potential and oxidation level of the doped PPy nanocomplexes have a confirmed association with particle size and electrical properties. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2329–2336     

Facile one‐step synthesis of electromagnetic functionalized polypyrrole/Fe3O4 nanotubes via a self‐assembly process

This article reports a simple self‐assembly process for facile one‐step synthesis of novel electromagnetic functionalized polypyrrole (PPy)/Fe₃O₄ composite nanotubes using p‐toluenesulfonic acid (p‐TSA) as the dopant and FeCl₃ as the oxidant. The key trick of the present method is to use FeCl₃ as the oxidant for both PPy and Fe₃O₄ in the same time to synthesize PPy/Fe₃O₄ composite nanotubes in one‐step. This facile one‐step method is much simpler than the conventional approach using the Fe₃O₄ nanoparticles as the additives. Compared to the similar composites synthesized using the conventional method, the as‐prepared PPy‐p‐TSA/Fe₃O₄ composite nanotubes using the facile one‐step self‐assembly process show much higher room‐temperature conductivity. Moreover, the composite nanotubes display interesting ferromagnetic behavior. The electrical properties of the PPy‐p‐TSA/Fe₃O₄ composite nanotubes are dominated by the amount of FeCl₃ while their magnetic properties are controlled by the amount of FeCl₂. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 320–326, 2010     

Design of free‐standing microstructured conducting polymer films for enhanced particle removal from non‐uniform surfaces

Efficient removal of particles from topologically‐complex surfaces is of significant import for a range of applications (e.g., explosive residue removal in security arenas). Here, we synthesize next‐generation polymeric particle removal swabs with tuned structural features to elucidate the influence of the polymer microstructure on the removal of trace particles from surfaces. Specifically, microstructured free‐standing films of the conducting polymer polypyrrole (PPy) were synthesized through template‐assisted electropolymerization techniques. The removal of polystyrene microspheres from representative aluminum surfaces of varying roughness was evaluated as a function of the PPy microstructure. PPy‐based microstructured swabs displayed increased particle trapping properties relative to non‐textured PPy‐based swabs and current commercial swabs. This increased effectiveness occurred from the more intimate particle‐swab contact, leading to increased van der Waals interactions for the microstructured swabs. Therefore, this effort provides critical design rules for the production of microstructured conducting polymer materials for their application toward advanced particle removal technologies. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1968–1974     

Reactive Template Synthesis of Polypyrrole Nanotubes for Fabricating Metal/Conducting Polymer Nanocomposites

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.     

Synthesis and Properties of Polypyrrole/Chitosan Composite Hydrogels

Conducting polymer hydrogels consisting of polypyrrole (PPy) and chitosan (CS) are prepared by static polymerization of pyrrole using methyl orange (MO) as the dopant and Fe₂(SO₄)₃ as the oxidant in the CS aqueous solution. PPy/CS composite hydrogels not only have good electrical conductivities, but also exhibit excellent swelling/deswelling behaviors due to the participation of one-dimensional conducting PPy blocks in the hydrogel network. The effects of the amount of the oxidant and ionic strength on the physical properties of PPy/CS composite hydrogels are studied in detail. The results show that PPy/CS composite hydrogels have improved water absorbencies in saline solutions compared with the conventional polyelectrolyte hydrogel.     

Carbon papers with conductive polymer coatings for use in solid-state supercapacitors

Conductive polymer-coated carbon papers have been fabricated through polymerisation of pyrrole-based monomers oxidised with various heteropolyacids. Smooth surfaces are obtained when multiple coatings are applied to the carbon surface and give good contact with the Nafion^® electrolyte. Cyclic voltammetry was used to study the electrodes and a.c. impedance and charge / discharge cycling was used to study membrane electrode assemblies (MEA). MEAs were fabricated using a hot-press technique.     

Synthesis and characterization of polypyrrole/graphite oxide composite by in situ emulsion polymerization

This work demonstrates a feasible route to synthesize the layered polypyrrole/graphite oxide (PPy/GO) composite by in situ emulsion polymerization in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) as emulsifier. AFM and XRD results reveal that the GO can be delaminated into nanosheets and well dispersed in aqueous solution in the presence of CTAB. The PPy nanowires are formed due to the presence of the lamellar mesostructured (CTA)₂S₂O₈ as a template. The results of the PPy/GO composite indicate the PPy insert successfully into GO interlayers, and the nanofiber‐like PPy are deposited onto the GO surface. Owing to π–π electron stacking effect between the pyrrole ring of PPy and the unoxided domain of GO sheets, the electrical conductivity of PPy/GO composite (5 S/cm) significantly improves in comparison with pure PPy nanowires (0.94 S/cm) and pristine GO (1 × 10^?6 S/cm). © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1329–1335, 2010     

Facile Synthesis of Polyaniline‐Polypyrrole Nanofibers for Application in Chemical Deposition of Metal Nanoparticles

Polyaniline‐polypyrrole (PANI‐PPy) nanofibers with high aspect ratios have been synthesized by a one‐step, surfactant‐assisted chemical oxidative polymerization from mixtures of aniline (An) and pyrrole (Py) monomers. PANI‐PPy nanofibers synthesized with an excess of either PANI or PPy show similar spectral (UV‐vis and FT‐IR) characteristics as the individual homopolymers, whereas nanofibers from an equimolar mixture of An and Py display unique spectral characteristics. PANI‐PPy nanofibers undergo a spontaneous redox reaction with metal ions to produce metal nanoparticles with various morphologies and/or sizes. These findings may open new opportunities for synthesizing functional polymer nanofibers and metal nanoparticles with controllable sizes and/or morphologies.

     

Synthesis and Characterization of Polypyrrole Nanoparticles and Their Nanocomposites with Poly(propylene)

Summary: Conducting polypyrrole (PPy) nanoparticles were synthesized via microemulsion polymerization. PP/PPy nanocomposites were prepared by melt-mixing of polypyrrole with polypropylene (PP) and processed with injection molding. Tensile tests have revealed that increasing amount of PPy increased the strength and the stiffness of the nanocomposite while limiting the elongation of PP. Thermal gravimetric analysis has showed that incorporation of PPy nanoparticles has improved the thermal stability of the nanocomposites. Increasing amount of PPy nanoparticles increases the conductivity of nonconductive PP up to 2,4.10⁻⁴ Scm⁻¹. The same techniques were used to characterize nanocomposites containing 2% w dispersant. Composites prepared with dispersant have involved smaller dimension PPy nanoparticles and exhibited improvement in some mechanical and thermal properties.