Characterization of Conducting Copolymer of Pyrrole via Pyrolysis Mass Spectrometry

In this work, structural and thermal characterization of BF₄ ^? doped copolymer of pyrrole (PPy) with 2‐methylbutyl‐2‐(3‐thienyl)acetate prepared by electrochemical polymerization were performed via a pyrolysis mass spectrometry technique. The pyrolysis mass spectrometry data of the copolymer PPy/PMBTA, and the homopolymers; polypyrrole, PPy, and poly(2‐methylbutyl‐2‐(3‐thienyl)acetate), PMBTA were analyzed and compared. It has been determined that when the electrochemical polymerization of pyrrole was achieved on a PMBTA coated anode through the thiophene moieties of PMBTA, thermal stability of PMBTA chains increased slightly and the decomposition of both units followed quite similar pathways indicating an increase in the thermal stability of PMBTA chains unlike what was observed for PTSA doped PPy/PMBTA copolymer.     

Effects of Reaction Sequence on the Colloidal Polypyrrole Nanostructures and Conductivity

The relationship between nanoscaled morphology and macroscopic electrical conductivity of polypyrrole (PPy) nanostructures was qualitatively investigated. The PPy nanostructures were prepared via microemulsion polymerization using ionic surfactants. The morphology of PPy was influenced by both the type of ionic surfactants and reaction sequences; specifically, the PPy structures were highly influenced by the reaction sequence when anionic surfactant of SDS was used. By changing reaction sequence, a gel-like PPy was formed influencing on the macroscopic electrical conductivity. The results indicate that the macroscopic conductivity of PPy is affected by its nanoscaled structures as determined by the reaction conditions.     

Polyamide grafted with polypyrrole: formation, properties, and stability

Conducting textiles of polyamide (PA) fabrics and polypyrrole (PPy) were prepared by in situ oxidative chemical polymerisation of pyrrole (Py) on the surface of PA textiles using FeCl₃ as oxidant. The anionic surfactant, dodecylbenzenesulphonic acid, was used as co-dopant during Py polymerisation on the textile surface. The influence of the monomer amount and polymerisation conditions on formation of the conducting PPy layer, conductivity, morphology, and stability of the prepared PA/PPy was studied. The conductivity of modified textiles decreased rapidly after the washing process, so a special Py-functionalised silane (1-(3-(triethoxysilyl)propylamino)-3-(1-H-pyrrole-1-yl)propan-2-ol; SP) was synthesised and applied to the PA surface prior to PPy formation. The presence of SP on the PA surface after completion of the sol-gel process was verified by Fourier transform infrared spectroscopy with an attenuated total reflectance. Pyrrole polymerisation was subsequently applied to the SP pre-treated textile surface. The influence of SP concentration on both the fastness of the conducting layer after the washing process and stability of the electrical conductivity of the prepared PA/PPy samples was investigated. Surface conductivity of the samples treated and untreated by the sol-gel process of SP was measured both prior to and after washing of the prepared textiles. It was found that an application of 0.6 mass % of SP significantly improved the fastness of the PPy layers. Examination of the modified PA surface using scanning electron microscopy disclosed the differences in the formation of PPy on PA textiles when using SP and also showed differences on the PPy modified textile surface prior to and after washing. The method of X-ray photoelectron spectroscopy was used for a detailed study of the surface composition. It was confirmed that the pre-treatment with Py-functionalised triethoxysilane significantly influenced the chemical composition of the PA surface modified with PPy.     

Preparation of polypyrrole/multi-walled carbon nanotube hybrids by electropolymerization combined with a coating method for counter electrodes in dye-sensitized solar cells

In this work, multi-wall carbon nanotubes coated with polypyrrole (PPy/MWCNT) have been used as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). PPy was deposited onto fluorine-doped tin-oxide-coated glass by electrochemical polymerization of pyrrole. Three surfactants were used in the preparation of the hybrids: cationic cetyltrimethylammonium bromide, anionic sodium dodecylbenzenesulfonate (DBSNa), and non-ionic polyoxyethylene sorbitan monolaurate (Tween20). The morphologies of the PPy and PPy/MWCNT hybrids were investigated using scanning electron spectroscopy. Chemical composition of the prepared CEs was determined by X-ray photoelectron spectroscopy and Fourier-transformed infrared spectroscopy. The catalytic activity of the PPy and PPy/MWCNT layers was evaluated using cyclic voltammetry, and the photovoltaic properties of DSSCs with PPy and PPy/MWCNT CEs were characterized using I–V measurements. PPy/MWCNT samples that were prepared by electrochemical polymerization showed the best results when the anionic surfactant DBSNa was used during polymerization. The photoelectric conversion efficiency of PPy/MWCNT prepared by electrochemical polymerization was 2.9%, which was 59% of that of Pt CE (4.9%).     

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.     

Synthesis and characterization of poly (indene‐co‐pyrrole) nanofibers

Nanofibers of poly (indene‐co‐pyrrole) (CInPy) have been synthesized, using a facile chemical oxidative polymerization reaction. The effect of copolymerization was examined in view of the individually synthesized homopolymer nanostructures of polyindene (PIn) and polypyrrole (PPy). Morphological details of CInPy, studied using scanning electron microscopy (SEM) and transmission electron microscopy, (TEM) reveal the appearance of dense cottony mess, comprising of fine fibers with an average diameter of 5–10 nm. Chemical structural analysis of CInPy, conducted using ultraviolet‐visible (UV‐Vis), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopic techniques, reveals that both PIn and PPy are involved in the formation of copolymer organization. Fluorescence properties of nanosized copolymer are observed in the blue region, with emission λ_max placed at 395 nm. Conductivity of copolymer nanofibers (2.4 × 10^?3 S/cm) is consistent with the morphology and thermal stability properties of integral homo‐polymers. Improved thermal stability and processability along with the enhanced optical and electrical properties of copolymer nanostructures outfit it as a better promising material in optoelectronic and light emitting nanodevices, with reference to nanosized PIn and PPy. Copyright © 2009 John Wiley & Sons, Ltd.     

纳米石墨薄片/聚吡咯复合材料的制备及导电性能

膨胀石墨经过超声处理制备了纳米石墨薄片。以其为导电填料，对甲苯磺酸为掺杂剂，FeCl₃·6H₂O为氧化剂，引发吡咯单体发生原位聚合，制备出纳米石墨薄片/聚吡咯(NanoGs/PPy)复合材料。利用红外光谱(FTIR)、扫描电镜(SEM)和透射电镜(TEM)表征了材料的组成和结构。结果表明，石墨薄片被聚吡咯完全包覆；并且以纳米级尺寸分散在聚吡咯基体中。热失重(TG)分析和电导率测试结果表明，复合材料的耐热性能和导电性能较纯聚吡咯有所提高。     

Preparation of conductive polypyrrole (PPy) composites under supercritical carbon dioxide conditions

Electrically conductive composites were prepared via the chemical oxidative polymerization of the pyrrole monomer in polystyrene (PS) and zinc neutralized sulfonated polystyrene (Zn-SPS) films under supercritical carbon dioxide (SC-CO₂) conditions. The strong swelling effect of SC-CO₂ made polypyrrole (PPy) particles not only form on the surface, but also become incorporated into the film, resulting in a homogeneous structure with a relatively higher conductivity. By comparison, the composite prepared in aqueous solutions shows a skin-core structure and a conductivity of 3 to 4 orders of magnitude lower than that of the former due to the diffusion-controlled process of the pyrrole monomer. The percolation thresholds of PS/PPy and Zn-SPS/PPy composites were 6.2% and 2.7% of the volume fraction of PPy, respectively, much lower than the theoretically predicted value of 16%. Moreover, the conductive composites prepared under SC-CO₂ conditions showed higher thermal stability, especially in the high-temperature region. Translated from Chemical Journal of Chinese Universities, 2006, 27(4): 771–774 (in Chinese)     

Organic–inorganic polypyrrole‐surface modified SiO2 hybrid nanocomposites: a facile and green synthetic approach

Organic–inorganic hybrid nanocomposites composed of conductive polypyrrole (PPy) and surface modified silica (SiO₂) were successfully prepared through an in situ chemical oxidative polymerization in supercritical carbon dioxide (scCO₂). SiO₂ nanoparticles were surface modified using 3‐methacryloxypropyltrimethoxysilane (MPTMS) in order to disperse well in the medium. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the SiO₂ nanoparticles were encapsulated into the polymer. UV‐visible spectra of the diluted colloidal dispersions of PPy/SiO₂ hybrid nanocomposites were similar to those of PPy system. Fourier transform infrared spectroscopy (FT‐IR) suggested the strong interaction between PPy and SiO₂. Surface characterizations of nanocomposites were described by X‐ray photoelectron spectroscopy (XPS). The nanocomposites synthesized in scCO₂ have been shown to possess higher electrical conductivity and thermal stability. Copyright © 2009 John Wiley & Sons, Ltd.     

Lab Scale Study on Humidity Sensing and D.C. Conductivity of Polypyrrole/Strontium Arsenate (Sr<Subscript>3</Subscript>(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript>) Ceramic Composites

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.     

聚ε-己内酯/聚吡咯电纺膜的制备与性能

以吡咯(Py)和聚ε-己内酯(PCL)为原料、氯仿为溶剂,并掺杂一定量的十二烷基硫酸钠制备电纺膜,利用三氯化铁的氧化作用原位生成聚吡咯(PPy).对所得到的PCL/PPy电纺膜用红外光谱进行表征,在扫描电镜和透射电镜下观察纤维形貌,并测定力学性能和体积电阻率.结果表明,所生成的PPy以纳米粒子形式附着在电纺纤维表面,随着Py相对于PCL的质量百分含量由0增加到20%,PCL/PPy电纺膜的纤维直径从(730±341)nm逐渐下降至(325±84)nm;膜的拉伸模量和拉伸强度由不含Py的(25.7±0.8)MPa和(2.48±0.14)MPa分别增加至含有20%Py的(48.4±7.6)MPa和(5.05±0.59)MPa,断裂伸长率由(129±27)%下降至(86.2±9.1)%;体积电阻率降低了2～3个数量级.该PCL/PPy电纺纤维膜以期可作为电活性材料用于功能或生物医用领域.     

Synthesis of conducting polypyrrole by radiolysis polymerization method

Conducting polypyrrole (PPy) has been synthesized by the in situ gamma radiation‐induced chemical oxidative polymerization method. This method takes advantages of the specialties of radiation‐induction, and a highly uniform polymer morphology was obtained. The resultant nanosize polypyrrole particles were characterized by Elemental Analysis, Fourier transform infrared (FT‐IR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and X‐ray Diffraction (XRD). Measurements of polymer particle sizes were obtained at <500 nm. A standard four‐point probe revealed that the chemical synthesis of PPy has a good electrical property. Also thermal stability, checked by Thermal Gravimetric Analysis in air, was ensured by this novel synthesis. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of polypyrrole nanoparticles by batch and semicontinuous heterophase polymerizations

Nanoparticles of semiconducting polypyrrole (PPy) were synthesized by batch heterophase (BHP) and semicontinuous heterophase polymerization (SHP) using ferric chloride (FeCl₃), potassium persulfate (KPS), or ammonium persulfate (APS) as the oxidizing agent, sodium dodecyl sulfate (SDS) as surfactant, and ethanol (EtOH) or iso-pentyl alcohol (iC₅OH) as co-surfactants. In all cases, the molar ratios of monomer/oxidizing agent were 1/1. Pyrrol polymerization by BHP and SHP allowed using much lower percentages of surfactant than those employed in microemulsion polymerization of this monomer. The effects of temperature, oxidizing agent, and co-surfactant on conductivity were studied. The polymers were analyzed by transmission electron microscopy (TEM), UV/Visible and Fourier transform infrared (FTIR) spectroscopies, and cyclic voltammetry. Higher PPy conductivities were obtained by polymerizing at 0 °C with FeCl₃ as the oxidizing agent, in the presence of iC₅OH as co-surfactant. When the reaction was carried out by SHP with low reaction times, smaller particles with similar conductivities were obtained compared to those obtained by BHP; the conductivity of PPy decreases with increasing polymerization time, which can be explained by PPy overoxidation.     

Microstructure, distribution and properties of conductive polypyrrole/cellulose fiber composites

Highly intrinsic conductive polypyrrole/cellulose fiber composites (CF) were successfully prepared through in situ chemical oxidation polymerization simply by increasing fiber concentration at the same dosage of pyrrole, oxidant and dopant (based on the weight of dry fiber). FeCl₃ and anthraquinone-2-sulfonic acid sodium salt (AQSNa) were utilized as oxidant and dopant. As fiber concentration increased from 1 % (CF1) to 20 % (CF20), N and S content increased from 0.24 and 0.25 % to 1.24 and 0.89 %, and great increase in the retention of PPy and AQSNa was confirmed by elemental analysis. In addition, on the surface of conductive fiber, PPy of compact fibroid structure was detected instead of interconnected globular structure at higher fiber concentration. Furthermore, scanning transmission electron microscope and X-ray photoelectron spectroscopy (XPS)-depth profile analysis demonstrated denser and more uniformly distributed PPy inside fiber wall for CF20, while PPy tended to deposit on the surface of fiber for CF1. Fourier transform infrared spectroscopy, together with XPS certified that the PPy with longer conjugation length and higher doping level across the conductive fiber was obtained at higher fiber concentration. The doping level for CF10 decreased from 21.55 to 16.39 % with increasing fiber wall thickness, while that of CF20 decreased slightly from 30.73 to 24.10 %. The resulting CF20 showed lowest surface resistivity of 0.433 KΩ/square, as well as improved electro-conductivity stability. The incorporation of more PPy in CF improved the thermal stability.     

Conductive Composite Materials of Polyethylene and Polypyrrole with High Modulus and High Strength

Composite films of polyethylene (PE) and polypyrrole (PPy) were prepared by polymerization of PPy on an ultradrawn polyethylene film with high modulus and high strength in ferric chloride (FeCl₃) aqueous solution. The electrical conductivity of the composite film was found to be related to the polymerization conditions, such as polymerization temperature, polymerization time, the concentration and the oxidation potential of the FeCl₃ solution. Scanning electron microscopy, FTIR and ¹³C NMR spectra were used to elucidate the morphological and structural variations of PPy prepared under different conditions, which lead to the differences in the electrical properties of the resultant composite films. The best electrical conductivity of the composite was about 5.5 S/cm for the film prepared under optimum conditions. The Young's modulus and the tensile strength reached 80 GPa and 3.2 GPa, respectively, which indicated the successful production of a conductive polymer with high strength and high modulus.     

Investigation of Copolymers of Thiophene‐Functionalized Polystyrene with Pyrrole by Pyrolysis Mass Spectrometry

The thermal and structural characterization of electrochemically synthesized thiophene‐functionalized polystyrene and pyrrole (PS/PPy) and their copolymers were investigated by direct pyrolysis mass spectrometry. The pyrolysis data confirmed the growth of polypyrrole onto the pendant thiophene moiety of polystyrene. It is determined that the electrolytic film has different properties from the mechanical mixture and the related homopolymers.     

Synthesis of polypyrrole micro/nanofibers via a self-assembly process

Novel polypyrrole (PPy) micro/nanofibers were synthesized via a self-assembly process by using 4-hydroxy-3-[(4-sulfo-1-naphthalenyl) azo]-1-naphthalenesulfonic acid (Acid Red B) as dopant and ferric chloride (FeCl₃) as oxidant. Experimental conditions, including the concentration of the dopant, reaction temperature and stirring state have been investigated for their influences on the morphology of the synthesized PPy micro/nanofibers. The products were characterized by scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy. The formation mechanism of micro/nanofibers was studied. It is believed that the micelles formed by the dopant and pyrrole monomer act as templates during the synthesis process. Two functions of aggregation and synthesis are proposed in the reaction system simultaneously, and the morphologies of micro/nanofibers are the co-operations of these two functions. The maximum conductivity value of the PPy micro/nanofibers was 8.56 S cm^?1     

Surface reactivity of polypyrrole/iron-oxide nanoparticles: electrochemical and CS-AFM investigations

Composite materials based on iron-oxide nanoparticles (magnetite, hematite, and maghemite) and tetraoxalate-doped polypyrrole (PPy) were electrochemically generated from aqueous solutions. Their composition was determined using electrochemical quartz crystal microbalance experiments. The oxide percentage in mass was found to vary from 17 to 27% depending on the oxide identity. They were all shown to be fascinating candidates as protective materials against corrosion of iron and carbon steel materials although maghemite-nanoparticle-loaded polypyrrole films offer the best performances. An anionic surfactant (sodium dodecylsulfate) was added to the electrodeposition solution to avoid the formation of clusters. These anions were also shown to improve the conductivity of the resulting PPy films, while the presence of oxide nanoparticles tends to decrease this same surface conductivity. On the other hand, the correlation between the morphology and the local conductivity appears to be more obvious in the absence of anionic surfactants than in their presence. This aspect is discussed although it still needs further investigation. Contribution to the International Workshop on Electrochemistry of Electroactive Materials (WEEM-2006), Repino, Russia, 24–29 June 2006.     

Growth of aligned polypyrrole acicular nanorods and their application as Pt‐free semitransparent counter electrode in dye‐sensitized solar cell

Polypyrrole films on fluorine doped tin oxide (FTO)‐coated glass substrate were prepared in situ by placing FTO/glass substrates where pyrrole was polymerized by methyl orange‐ferric chloride complex. The atomic force microscopy image indicated growth of acicular nanorods of polypyrrole. These films exhibited catalytic activity towards I₃⁻/I⁻ redox couple and have been investigated for counter electrode application in dye‐sensitized solar cell (DSSC). The fabricated DSSC with N719 dye/TiO₂ as photoanode, and PPy/FTO as counter electrode shows ~1.7% efficiency.     

On the break-in and passivation phenomena in polypyrrole/sulfate films

The influence of different divalent cations (M²⁺) on the electrochemical charging/discharging process of polypyrrole/sulfate (PPy/SO₄) films has been investigated. In principle, two different types of M²⁺ were found: (a) cations that cause the break-in phenomenon in the PPy film during electrochemical cycling with a gradual increase of film electroactivity and (b) cations in whose solutions the PPy film remains mainly electroinactive. Certain correlations have been drawn between several physico-chemical properties of the investigated cations and the break-in and passivation phenomena. The break-in and passivation phenomena were found to be influenced by the size and deformability of the cation hydration shell, ion covalent index and softness, as well as by the pH value of the test solution.