Ionic interactions in polyacrylonitrile/polypyrrole conducting polymer composite

A conducting polymer composite was prepared by the postpolymerization of pyrrole in a polyacrylonitrile (PAN) matrix film. To enhance the electrostatic interaction between the two phases, a small amount of a sulfonate or a carboxylate (COO⁻) group was incorporated into the PAN structure. The presence of electrostatic interaction between the conducting polypyrrole and the anion-containing PAN copolymer was elucidated by examination of the morphology and the electrical properties of the composite. The aromatic sulfonate-containing matrix provided the composite with the best results in the electrical conductivity, the environmental stability of conductivity, and the morphological property. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2641–2648, 1998     

Conducting poly(styrene‐co‐divinylbenzene)/polypyrrole PolyHIPE composite foam prepared by chemical oxidative polymerization

Conducting poly(styrene‐co‐divinylbenzene)/polypyrrole (PPy) polyHIPE (polymerized high internal phase emulsion) composite foams were synthesized via chemical oxidative polymerization method. The effect of solvent and dopant type on the surface morphology and electrical conductivity of composite foams has been investigated. SEM micrographs showed that the morphology of PPy thin film on the internal surface of poly(styrene/divinylbenzene) (poly(St‐co‐DVB) polyHIPE support foam strongly depends on the solvent and dopant type used. Incorporation of dodecylbenzene solfunic acid‐sodium salt (DBSNa) as a dopant in chloroform solvent resulted in formation of a PPy thin film with higher molecular compact structure and electrical conductivity on the support foam as compared to other solvents and another dopant used. Fourier‐transform infrared spectroscopy was used to correlate the electrical conductivity of composite foams to their PPy structural parameters. As expected, the extended conjugation length of PPy in the presence of DBSNa dopant is the main reason for higher electrical conductivity of resultant composite foam. Electrical conductivity measurements revealed that the chemical aging of various conducting foams follows the first‐order kinetic model, which is a representative of a reaction‐controlled aging mechanism. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and properties of conducting arachidic acid/polypyrrole composite langmuir–blodgett films

Electrically conducting arachidic acid/polypyrrole (PPy) composite films were prepared by exposing the arachidic acid LB films containing ferric chloride to pyrrole vapor. The optimum conditions to deposit matrix LB film were the subphase temperature of 23–25°C, pH of 6.0 and ferric chloride concentration of 5.0 × 10⁻⁵ M. The formation of PPy in the arachidic acid matrix LB films was confirmed by UV-visible spectra, FTIR spectra, and scanning electron micrographs. The average thickness of the composite LB films prepared at 0°C was 1525 Å. The composite films prepared at lower temperatures have more uniform surface and exhibit higher electrical conductivity than the films prepared at higher temperatures do. The in-plain conductivity and the transverse conductivity of the composite film were 10⁻³−10⁻² S/cm and 10⁻⁶S/cm, respectively, and, thus, the conductivity anisotropy was about 10³ © 1996 John Wiley & Sons, Inc.     

Effect of silver decorated graphene oxide on the PEDOT:PSS-matrix composite films

Silver decorated graphene oxide (GO) was added in poly(3,4-ethylenedioxythiopphene): poly(styrene sulfonate) (PEDOT:PSS) matrix to fabricate composite films, aiming for an improved electrical conductivity. Silver particles were deposited on GO surfaces by reaction with Tollens’ reagent. The composite films reinforced by silver decorated GO showed a sheet resistance of 744 Ω/sq. with 88.9% transparency, which outperformed PEDOT:PSS matrix and GO/PEDOT:PSS composite films. The deposited silver particles were consisted of elementary silver and positively charged silver. The GO surfaces were negatively charged. The distinction of positive domain and negative domain on silver decorated GO surfaces promoted the phase separation of conductive PEDOT molecules and insulting PSS molecules, which contributed to the increase of the electrical conductivity of the composite films. Moreover, the deposition of elementary silver introduced extra electron pathways in the composite films.     

Conductive polypyrrole composite films prepared using wet cast technique with a pyrrole–cellulose acetate solution

Conductive polypyrrole‐cellulose acetate films were prepared from cellulose acetate (CA) solution of pyrrole (Py) using wet cast method. In the composite films, Py was used as a solvent for CA which was dissolved with different concentration. Then, to prepare PPy–CA composite film, the Py viscous solution of CA was cast on glass plate and immersed in FeCl₃ aqueous solution. When the CA film was formed in the aqueous solution, the polymerized PPy particles having about 1 μm diameter were formed in composite film. The resultant composite films were characterized, showing good film fabrication and electrical conductivity of around 6.9 × 10^?4 to 3.6 × 10¹ S/cm. POLYM. ENG. SCI., 54:78–84, 2014. © 2013 Society of Plastics Engineers     

耐折高导电聚吡咯／聚硫橡胶复合膜

耐折高导电聚吡咯／聚硫橡胶复合膜马文石，贾振斌，龚克成（华南理工大学高聚物结构与性能改性研究室，广州，５１０６４１）将导电聚合物与绝缘聚合物复合，是改善导电聚合物性能的良好方法之一。Ｗａｎｇ等［１～３］采用二步法将聚吡咯（ＰＰｙ）与聚苯乙烯、聚碳酸酯...     

Preparation of poly(vinylidene fluoride)–polypyrrole composite films by electrochemical synthesis and their properties

Composite films of poly(vinylidenc fluoride–polypyrrole (PVDF–PPy) were prepared by electrochemical polymerization of pyrrole on a very thin PVDF matrix film (～ 0.5 μm). The polymerization was carried out in aqueous media using stainless steel, coated with PVDF matrix, as a working electrode, and p-toluene sulfonate (PTS), as a dopant. The films were prepared at different voltages for different durations of time in order to optimize the conditions of composite formation. The resulting films were characterized by studying IR spectra, conductivity, SEM, XRD, and tensile strength measurements. The mechanical properties of the composites were found to have improved, while the conductivity remained more or less same as that of pure PPy. © 1995 John Wiley & Sons, Inc.     

Electrochemical properties of polypyrrole/sulfonted SEBS composite nanofibers prepared by electrospinning

The electrochemical behavior of electrospun polypyrrole (PPy)/sulfonated-poly(styrene-ethylene-butylenes-styrene) (S-SEBS) composite nanofibers was investigated, compared to PPy/poly(styrene-ethylene-butylenes-styrene) (SEBS) fibers prepared by a casting method. The electrospun PPy/S-SEBS (E-PSS) fibers were about 300 nm in average diameter, while PPy/SEBS composite (C-PS) prepared by a casting method showed the granular macroporous structure. The effect by both electrospinning and sulfonation results in higher electrochemical capacity due to the increase of doping level, high electrical conductivity, low interfacial resistance, and high reversibility by easy intercalation of Li ion. In addition, sulfonated SEBS induces higher elongation force to jet in the processing of electrospinning due to the role of dopant.     

Effect of polymer blending on the electrical conductivity of polypyrrole/copolyester composite films

Summary The effect of polymer blending on the electrical conductivity of polypyrrole/copolyester composite film was investigated. Copolyesters containing sodium sulfonate group with various main chain structures were synthesized and blended with PET. The average anionic group contents in the blend samples were controlled to be 3.5 and 6.1 mol%. The polypyrrole composite films were prepared by polymerization of pyrrole through vapor phase absorption onto the copolyester-PET blend films which contained FeCl₃. The conductivity of the blend samples containing 3.5 mol% of DMS was greater than that of the copolyester of the same DMS content when the pyrrole vapor exposure time was longer than 30 min. The blends of 6.1 mol% of DMS showed higher conductivity than the copolyesters of the same DMS amount even when the exposure time was short. The high electrical conductivity of the blend samples was thought to be due to the phase separation between PET and copolyesters in amorphous region. Received: 1 June 1998/Revised version: 5 October 1998/Accepted: 30 October 1998     

Carbon black thin films with tunable resistance and optical transparency

Layer-by-layer assembly was used to produce highly conductive thin films of carbon black and polymer. Positively and negatively-charged polyelectrolytes, polyethylenimine (PEI) and poly(acrylic acid) (PAA), were used to stabilize carbon black in aqueous mixtures that were then deposited onto a PET substrate. The effects of sonication and pH adjustment of deposition mixtures on the conductivity and transparency of deposited films was studied, along with drying temperature. Sonication and oven drying at 70 °C produced films with the lowest sheet resistance (∼1500 Ω/sq), which is a bulk resistivity below 0.2 Ω cm for a 14-bilayer film that is 1.3 μm thick. These two variables improve packing and connectivity amongst carbon black particles that results in increased electrical conductivity. Increasing the pH of the PAA-stabilized mixture and decreasing the pH of the PEI-stabilized mixture resulted in transparent films due to increased polymer charge density. These pH-adjusted films have much higher sheet resistance values than their non-adjusted counterparts due to their reduced thickness and patchy deposition. Varying the number of bilayers allows both sheet resistance and optical transparency to be tailored over a broad range. Carbon black-filled thin films able to achieve these levels of resistivity and transparency may find application in a variety of optoelectronic applications.     

Preparation of highly conducting and spin-probed polypyrroles using coupled electrochemical-chemical synthesis in the presence of nitroxyl radicals

Summary A new method for the synthesis of conducting polypyrroles (PPy), based on chemical and combined electrochemical-chemical oxidation of pyrrole monomers in the presence of nitroxyl radical (TEMPOL-2,2,6,6-tetramethyl-4-hydroxy-1-oxy-piperidyl) as oxidation agent (in its oxidation state) and redox mediator respectively is described. The PPy films obtained are extremely porous and the electrical conductivity () of the resulting PPy samples ranges from 1 to 100 S cm^–1. PPy prepared in aqueous solutions has a lower conductivity 1 S cm^–1 as compared to the PPy prepared in acetonitrile solutions with conductivity of about 100 S cm^–1. The PPy films are quite compact and thick films (1 mm) can be pealed off from the electrode surface and pressed as a disc for further studies. Only after partial reduction of polypyrrole film the spin-probed PPy was obtained. The concentration of nitroxyl radicals incorporated in the polymer matrix can be changed using various degrees of polymer reduction. The anisotropic broadening of the observed ESR lines indicates a low mobility of incorporated nitroxyl radicals in the PPy matrix. The electronic interaction between the nitroxyl groups and the paramagnetic centers of the polymer chains, polarons, causes an ESR line broadening of polaron signal both on air (1.1 mT) and in vacuum (0.7 mT) as compared to unmodified PPy (0.2 mT on air, 0.05 mT in vacuum).     

Nafion/PTFE Composite Membranes for Fuel Cell Applications

The composite membranes were prepared by impregnation of porous poly(tetrafluoroethylene) membranes with a 5 wt% Nafion solution. Scanning electron microscope micrographs of composite membranes show the surface and cross section of poly(tetrafluoroethylene) membranes were covered and filled with Nafion resin. Comparison of physical properties and fuel cell performance of composite membranes with those of Nafion membranes (DuPont Co) is presented. The composite membrane has better thermal stability and gas barrier property but worse ionic conductivity than Nafion membrane. Though the composite membrane has a lower conductivity than Nafion membrane, however, owing to the thinner thickness of composite membrane (in thickness of 20±5µm) than Nafion-115 (in thickness of 125µm) and Nafion-117 (in thickness of 175µm) membranes, the composite membrane has a shorter H⁺ ion transporting pathway and thus a higher conductance (conductance = conductivity/membrane thickness) than Nafion-115 and Nafion-117 membranes. Thus the composite membrane has a better fuel cell performance than Nafion-117 and Nafion-115 membranes. In this report, we show that our composite membrane has a fuel cell performance similar to Nafion-112 membrane (in thickness of 50µm).     

The conducting behavior and stability of conducting polymer composites

Results of measurements of the electrical conductivity of low density polyethylene/polypyrrole and polystyrene/polypyrrole composites are reported. It is observed that the electrical conductivity of the composite vs. concentration follows the power law predicted by the percolation theory. The manufacturing process influences the homogeneity of the composite at microscopic scale and thus the percolation threshold. Annealing studies show that the stability of the electrical conductivity of the composite is related to the thermal expansion of the polymers and the relaxation of the polymer chains. The decrease of the electrical conductivity of the composite is attributed to the interruption of the percolation path.     

Effect of solvent on electrical conductivity and gas sensitivity of PEDOT: PSS polymer composite films

Poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) was blended with polyethylene oxide (PEO) and polyvinyl alcohol (PVA) and composite film was cast. Additional solvents of dimethyl sulfoxide (DMSO) and ethylene glycol (EG) were mixed and their effects on electrical conductivity and structural changes were investigated. The electrical conductivity increased in response to the additional solvent, leading to an increase in the PEDOT ratio relative to the control. PEDOT:PSS/PEO composite film had a much higher electrical conductivity than PEDOT:PSS/PVA. When blended with PEO, the quinoid structure revealed by Raman spectroscopy increased relative to the PVA‐blended case, indicating higher electrical conductivity. The current–voltage response and gas sensitivity showed much better performance in PEDOT:PSS/PEO/DMSO composite film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42628.     

Conducting Shape Memory Polyurethane‐Polypyrrole Composites for an Electroactive Actuator

Summary: Electroactive shape memory composites were prepared using polyurethane block copolymer and conducting polypyrrole by chemical oxidative polymerization. The electrical conductivity, thermal and mechanical properties, and morphology of the composites were investigated, and a voltage‐triggered shape memory effect was demonstrated. The polyurethane synthesized had a transition temperature near 46 °C. The presence of polypyrrole increased the conductivity of the composites, and a high conductivity of the order of 10^?2 S/cm was obtained at 6–20 wt.‐% polypyrrole. Such a conductivity of composites was enough to show electroactive shape recovery by heating above the transition temperature of 40–45 °C due to melting of the polycaprolactone soft segment domain. Thus a good shape recovery of 85–90% could be obtained in the shape recovery test with bending mode when an electric field of 40 V was applied.

Electroactive shape recovery behavior of PU/PPy composite.     

Effect of copolyester structure on the conductivity of polypyrrole/copolyester composite films

The effect of ionic group content and main chain structure of copolyesters on the electrical conductivity of polypyrrole/copolyester composite films was investigated. The composite films were prepared by polymerizing pyrrole through vapor phase absorption onto the copolyester films that contained FeCl₃. The conductivity of polypyrrole/copolyester composite films increased with the DMS content and reached its maximum when the DMS content reached about 10 mol%. The conductivity increased dramatically when DMS content was more than 5 mol% that was considered as the critical composition for polypyrrole continuity. The conductivity increased with the EG content at the same DMT/DMI ratio and showed maximum when DMT : DMI ratio was 1 : 1. Received: 16 June 1997/Revised: 22 August 1997/Accepted: 29 August 1997     

Dispersion of graphite nanosheets in a polymer matrix and the conducting property of the nanocomposites

Poly(methyl methacrylate)(PMMA)/expanded graphite composite has been made via an in situ polymerization of methyl methacrylate(MMA) in the presence of expanded graphite obtained by rapid heating of the graphite intercalation compound (GIC). The composite was then blended with poly(vinyl chloride) (PVC) to form an electrically conducting composite. SEM, TEM and XRD showed that the graphite had been dispersed throughout the polymer matrix in the form of nanosheets with thicknesses of about 20 nm. The resulting composite showed excellent electrical conductivity despite a low concentration of graphite. The transition from an electrical insulator to an electrical semiconductor for the composite occurred when the graphite content was 3.5 wt%, much lower than that of conventional conducting polymer composites. Conductivity reached a maximum of 10^?4 s/cm at a graphite concentration of 5.0 wt%. This improvement of conductivity could be attributed to the high aspect ration (width‐to‐thickness) of the graphite nanosheets dispersed in the polymer matrix.     

Synthesis and structural investigation of conductive composites from cellophane and polypyrrole

A versatile method for preparing conducting composites from cellophane and pyrrole by an interface technique has been attempted. Polymerization of pyrrole into the porous matrix of cellophane produces black, flexible composite film with conductivity comparable to that of polypyrrole and mechanical properties very similar to cellophane. © 1994 John Wiley & Sons, Inc.     

Continuous vapor phase polymerization of pyrrole. I. Electrically conductive composite fiber of polypyrrole with poly(p-phenylene terephthalamide)

Electrically conductive polypyrrole (PPy)/poly(p-phenylene terephthalamide) (PPTA) composite fibers have been prepared by continuous vapor phase polymerization at a speed of 0.5 ～ 1.5 m/min. The main parameters have been examined, and the conducting fibers with the best properties of electrical conductivity 0.68 s/cm, tensile strength 2731 N/mm², and the elongation at break 4.8% were obtained by using FeCl₃ · 6H₂O as the oxidizing agent. The results of elemental analysis, wide-angle X-ray diffraction analysis and SEM of the composite fibers are also reported. © 1995 John Wiley & Sons, Inc.     

Surface structure of conductive polypyrrole‐containing composites

The surface structures of polypyrrole/silicon crosslinked poly( styrene/butyl acrylate/hydroxyethyl acrylate) (PSBH) conductive composite films were investigated by X‐ray photoelectron spectroscopy and scanning electron microscopy. It was found that the conductive composite films were of a “sandwich” structure, and the surfaces greatly differ in chemical compositions and phase morphologies from the bulk. The Si and N contents exhibit opposite gradient change with the measured depth of the two surface layers in the composite films, namely, the decrease in Si content and the increase in N content with increase in the depth of the surface layers. However, the N^δ+/N ratios in polypyrrole decreased with the measured depth of the conductive composite film. It was also found that the conductive composite film based on silicon crosslinked matrix exhibits more environmental stable than that based on linear matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 95–101, 1999