Multilayer photoactive nanocolloidal PPy:PSS as a novel substitute for Pt free counter electrode in DSSC

Water dispersible and highly processable, Polypyrrole (PPy) nanocolloidal particles were synthesized by chemical oxidation polymerization with 15 wt % of anionic polyelectrolyte poly(styrene sulfonate) (PSS) at 5°C has been reported in this work. This polymer composite (PPy:PSS) was competent with conventional Pt counter electrode (CE) when compared for dye sensitized solar cells (DSSCs). Morphological analysis revealed smooth and spherical shaped nanoparticles of PPy. Interaction between the SO₃H groups and Py units in PPy improved the thermal stability of PPy with higher doping levels of PSS. The nanocolloidal solution was spin coated at 4000 rpm. The layer by layer, self‐assembled multilayer thin films were used as CE in DSSCs. There was a linear dependence of DSSCs performance with film roughness for the self‐assembled multilayer PPy:PSS films. Single layer films showed better electrocatalytic behavior than multilayer films. All the PPy:PSS films had good electrochemical stability. The DSSC efficiency of 3.40% was observed for chemically oxidized PPy with 15 wt % PSS for single layer film, with a highest FF of 0.7154. The low cost, good performance, rapid and simple fabrication method of PPy:PSS composite modified CE could be a potential alternative for Pt in the DSSCs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43114.     

Electrically conductive composites of polyurethane derived from castor oil with polypyrrole‐coated peach palm fibers

Electrically conducting fibers were prepared through in situ oxidative polymerization of pyrrole (Py) in the presence of peach palm fibers (PPF) using iron (III) chloride hexahydrate (FeCl₃·6H₂O) as oxidant. The polypyrrole (PPy) coated PPF displayed a PPy layer on the fibers surface, which was responsible for an electrical conductivity of (2.2 ± 0.3) × 10⁻¹ S cm⁻¹, similar to the neat PPy. Electrically conductive composites were prepared by dispersing various amounts of PPy‐coated PPF in a polyurethane matrix derived from castor oil. The polyurethane/PPy‐coated PPF composites (PU/PPF–PPy) exhibited an electrical conductivity higher than PU/PPy blends with similar filler content. This behavior is attributed to the higher aspect ratio of PPF–PPy when compared with PPy particles, inducing a denser conductive network formation in the PU matrix. Electromagnetic interference shielding effectiveness (EMI SE) value in the X‐band (8.2–12.4 GHz) found for PU/PPF–PPy composites containing 25 wt% of PPF–PPy were in the range −12 dB, which corresponds to 93.2% of attenuation, indicating that these composites are promising candidates for EMI shielding applications. POLYM. COMPOS., 38:2146–2155, 2017. © 2015 Society of Plastics Engineers     

Conducting polypyrrole‐coated banana fiber composites: Preparation and characterization

In this study, conducting banana fibers (BF) were obtained through in situ oxidative polymerization of pyrrole (Py) on the BF surface using ferric chloride hexahydratate (FeCl₃·6H₂O) as an oxidant. Suitable reaction conditions are outlined for the polymerization of Py: oxidant/monomer molar ratio, Py concentration and polymerization time of 2/1, 0.05 mol.L⁻¹ and 30 min, respectively. Under these conditions, high‐quality conducting fibers containing polyPy and BF (PPy‐BF) were obtained with an electrical resistivity as low as 0.54 Ω.cm. The PPy‐BF was blended with different concentrations of polyurethane (PU) by mixing the two components in a vacuum chamber and then applying compression molding. The electrical resistivity of composites with 25 wt% of PPy‐BF was around 1.8 × 10⁵ Ωcm, which is approximately 10⁸ times lower than that found for pure PU. Moreover, PU/PPy‐BF composites exhibited higher mechanical properties than pure PU and PU/PPy, indicating that these conducting fibers can also be used as reinforcement for polymer matrices. The properties of the PPy‐BF obtained by the method described herein open interesting possibilities for novel applications of electrically conducting fibers, from smart sensors to new conducting fillers that can be incorporated into several polymer matrixes to develop conducting polymer composites with good mechanical properties.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Facile fabrication of polyaniline/polypyrrole copolymer nanofibers with a rough surface and their electrorheological activities

Hierarchical polyaniline/polypyrrole (PANI/PPy) copolymer nanofiber was prepared via a two‐step method and adopted as dispersing materials for electrorheological (ER) fluids. The first step was used to synthesize PANI nanofibers by a rapid mixing method. Subsequently, the PANI/PPy copolymer nanofibers with a rough surface were obtained using an in situ polymerization method continuously. The morphology of the resultant PANI/PPy copolymer nanofibers can be controlled by varying the amount of Py monomer in the secondary in situ polymerization method. The rough surface of PANI/PPy copolymer nanofibers were confirmed by scanning electron microscopy and transmission electron microscopy. The diameter of PANI/PPy nanofiber is within the range 100–200 nm. The obtained PANI/PPy copolymer particles all exhibit amorphous structure through X‐ray diffraction measurement. We also demonstrated that the hierarchical PANI/PPy copolymer nanofibers exhibited characteristic ER behaviors, which were investigated using a Haake rotational rheometer at various electric field strengths. The ER efficiency e for PANI‐1mLPPy and PANI‐2mLPPy ER fluids at shear rate 0.1 s⁻¹ is 36.6 and 28.5 under electric field strength E = 3 kV/mm, respectively. Low leaking current density is observed even at high electric field strength and wide plateau region appeared, which show a strong ER activity for the PANI/PPy composite nanofibers. The results also indicate that the PANI/PPy composite particles have distinctly enhanced ER effect compared with the pure PANI and PPy particles under electric stimuli. The significantly improved ER property of PANI/PPy‐based ER fluid is ascribed to the enhanced interfacial polarization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46289.     

Structural and electrochemical studies of PPy/PEG-LiFePO4 cathode material for Li-ion batteries

A simple chemical oxidative polymerization of pyrrole (Py) directly onto the surface of LiFePO₄ particles was applied to the synthesis of polypyrrole-LiFePO₄ (PPy-LiFePO₄) powder. The LiFePO₄ sample without carbon coating was synthesized by a solvothermal method. The polyethylene glycol (PEG) was used as additive during Py polymerization for increasing the PPy-LiFePO₄ conductivity. Properties of resulting LiFePO₄, PPy-LiFePO₄ and PPy/PEG-LiFePO₄ samples were characterized by XRD, SEM, TGA and galvanostatic charge-discharge measurements. These methods confirmed the presence of polypyrrole on LiFePO₄ particles and its homogeneous distribution in the resulting powder material. The PPy/PEG-LiFePO₄ composites show higher discharge capacity than pure LiFePO₄, as PPy/PEG network improves the electron conductivity. It presents specific discharge capacity of 153 mAh/g at C/5 rate.     

Supercritical carbon dioxide processing of conducting composites of polypyrrole and porous crosslinked polystyrene

Conducting composites (∼3 mm in thickness) of polypyrrole (PPy) and porous crosslinked polystyrene (PCPS) were prepared by first impregnating PCPS with iodine (I₂), and then contacting it with pyrrole (Py). Both these steps were carried out with and without supercritical carbon dioxide. The use of supercritical CO₂ as a solvent for I₂ and Py facilitated the transport and deposition of these substances in the pores of the permanently porous host and produced composites with conductivities as high as 10⁻³ S cm⁻¹. Moreover, the deposition of I₂ in the pores could be controlled via the CO₂ pressure. The bulk and surface conductivities of the composite exhibited percolation behavior with respect to the amount of the I₂ deposited, whereas the volume conductivity exhibited a stepwise transition at approximately 100 wt% PPy+I₂ complex formed (with respect to the original mass of PCPS). Optical micrographs suggest that non-uniform distributions of PPy are obtained in the pores below this transition.The percolation threshold was as low as 10 wt% so that the stability and mechanical strength of the composites were approximately the same as those of the host PCPS. This was verified by TGA and compressive strength measurements. The temperature dependence of the conductivity conformed with Mott's variable-range hopping (VRH) model for three-dimensional electronic transport. However, the data could be correlated equally well with the CELT model.     

Application of Conjugated Polymer–Platinum Group Metal Composites as Heterogeneous Catalysts

Composites of polyaniline (PANI) or polypyrrole (PPy) doped with chloride ions and Pt or Rh particles were prepared by chemical reduction of metal ions conducted in the presence of the polymers. Based on X-ray diffraction studies it was established that the composites contained metal nanoparticles (5–9 in size). However, according to SEM investigations metal particles were agglomerated (40 nm–1.1 μm in size). Redox activity of the composites in the catalytic isopropyl alcohol conversion was ca. ten times higher than the acid–base one. Pt dispersed in polymer matrices showed higher catalytic activity than Rh. PPy doped with chloride ions had a promoting effect on the activity of Pt catalysts.     

Preparation and characterization of coaxial mullite/polypyrrole fibrous nanocomposites via self‐assembling and in situ surface‐initiated polymerization

After mullite fibers particles (MFPs) were surface modified, conductive polypyrrole (PPy) layer was chemically grafted on the surface of the self‐assembled monolayer (SAM) coated MFPs, via in situ surface‐initiated polymerization, resulting in SAM‐MFPs/PPy composites. The composites possess high electrical conductivity at room temperature, weakly temperature dependence of the conductivity. The nanocomposite electrochemical properties displayed nearly symmetric charge–discharge characteristics and an ideal rectangular cyclic voltammogram. X‐ray diffraction analysis confirmed that the main peaks of SAM‐MFPs/PPy composites are similar to the SAM‐MFPs, which reveal that the crystal structure of SAM‐MFPs is well‐maintained after the coating process under polymerization reaction conditions and exhibit semicrystalline behavior. Thermogravimetric analysis shows that the thermal stability of SAM‐MFPs/PPy composites was enhanced and these can be attributed to the retardation effect of amine functionalized MFPs as barriers for the degradation of PPy. The morphology of SAM‐MFPs/PPy composites showed the coaxial fibrous structure. POLYM. COMPOS., 35:892–899, 2014. © 2013 Society of Plastics Engineers     

Structural characteristics of chemical vapor polymerized polypyrrole/polycaprolactam fiber composites

Structural characteristics of polypyrrole (PPy)‐coated polycaprolactam (PA6) fiber composites prepared by chemical vapor deposition, in the presence of ferric chloride as the oxidizing agent, were investigated. A multi‐layered coating structure was observed by transmission electron microscopy (TEM), where a compact and denser layer existed between the PPy and PA6 fibers with two diffused layers on each side of the denser layer. The compact layer had a thickness of 200–300 nm. The experimental results show that there was no chemical interaction between PPy and PA6 in the PPy‐coated PA6 fibers. However, there was a stronger interaction between PPy and PA6 molecules in the interphase of PPy‐coated PA6 fiber after heat treatment at elevated temperature. The surface morphology of PPy‐coated PA6 fibers changed with the application of different processing treatments, e.g. swelling and heat treatment. Copyright © 2005 Society of Chemical Industry     

Preparation,morphology, and conductivity of waterborne,nanostructured, cationic polyurethane/polypyrrole conductive coatings

To endow cellulose fiber papers with good conductivity and simultaneously retain the mechanical strength of the conductive paper, a kind of waterborne, nanostructured, cationic polyurethane (CPU)/polypyrrole (PPy) conductive coatings were developed to modify the paper surface. Fourier transform infrared spectroscopy, atomic force microscopy, and thermogravimetry–differential thermogravimetry demonstrated that the peak associated with hydrogen bonding between ? NH and C?O of CPU was shifted, and chemical bonds between CPU and PPy were formed. Good compatibility between CPU and PPy was simultaneously established. Transmission electron microscopy and atomic force microscopy also suggested that PPy was encased and embedded in the CPU colloidal particles in a uniform style, and the surface of the CPU/PPy film was covered with a smooth, coherent conductive layer. With increasing pyrrole (Py) content from 5 to 20 wt %, the particle size increased from 55.08 to 74.59 nm, and the dispersity index (DPI) decreased. In addition, the conductivity of CPU/PPy increased from 0.1 to 5.0 S/cm. When the Py content was greater than 20 wt %, apparent increases in the particle size and DPI were detected as was particle coagulation; this resulted in decreased conductivity. Compared with the uncoated paper, the paper coated with CPU/PPy dispersions displayed different surface morphologies. The surface of the paper was completely enwrapped by the CPU/PPy conductive films when the coating amount was 45.42 g/m². With increasing coating amounts from 10.35 to 67.86 g/m², the conductivity of the conductive coated paper increased from 2.78 × 10^?3 to 2.16 S/cm, the tensile strength increased from 35.3 to 60.4 N m/g, and the conductive coated paper displayed good conductivity stability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41445.     

Conducting Composites of Polyurethane Resin and Polypyrrole: Solvent‐Free Preparation,Electrical, and Mechanical Properties

Summary: Three methods were used for solvent‐free preparation of conducting composites of PUR and PPy. In all cases, PUR was prepared from TDI and hydroxol 15‐W as polyol cross‐linker, whereas PPy was obtained upon oxidative coupling of Py using ferric chloride as oxidant. In method 1, PPy powder was dispersed in hydroxol. After addition of TDI the mixture was cured to yield the final product. In method 2, ferric chloride and Py were dissolved in hydroxol and a PPy dispersion was obtained. Then TDI was added and the final product was obtained upon curing. In method 3, Py was dissolved in TDI and ferric chloride dissolved in hydroxol. Then the two solutions were mixed and cured resulting in the simultaneous formation of PPy and PUR. Method 1 led to composites with a specific electrical conductivity σ of 10^?10 S · cm^?1 and a Shore A hardness of 40 to 55. Using methods 2 and 3, composites with σ values of 10^?7 S · cm^?1 and a hardness of 30 to 40 were obtained. Presence of moisture increased the σ values and decreased the hardness. Due to the solvent‐free preparation, the maximum PPy content of the samples was limited to 10 wt.‐%. The studies also demonstrated that the conductivity was mainly dependent on the amount of ferric chloride present in the sample and not on the PPy content, suggesting that the conductivity was ionic.

Flow diagram of different preparation methods for PUR–PPy composites.     

Effect of CuBr2 salt treatment on the performance of nanocolloidal PPy:PSS multilayer thin film counter electrodes of dye‐sensitized solar cells

A thin Pt layer on fluorine‐doped tin oxide (FTO) glass is commonly used as the counter electrode (CE) for dye‐sensitized solar cells (DSCs). We have investigated thin layers on FTO glass made from spherical polypyrrole (PPy)–poly(styrene sulfonate) (PSS) nanocolloidal particles with and without treatment of CuBr₂ and used them as CEs. The colloidal polymer composite (PPy:PSS) was spin‐coated at 4000 rpm, and PPy:PSS multilayer (one, three, five) films were employed as the CEs. Aqueous solutions of CuBr₂ (0.5 M and 1 M) were coated onto the multilayer CEs, which increased the efficiency of DSCs. When compared with the untreated PPy:PSS counter electrodes, the CuBr₂‐treated PPy:PSS films showed lower charge‐transfer resistance, higher surface roughness, and improved catalytic performance for the reduction of . The enhanced catalytic performance is attributed to the interaction of the superior electrocatalytic activity of PPy:PSS and CuBr₂ salt. Under standard AM 1.5 sunlight illumination, the counter electrodes based on a single‐layer PPy:PSS composite with 0.5 M and 1 M CuBr₂ salt treatment demonstrated power conversion efficiencies (PCE) of 5.8% and 5.6%, respectively. These values are significantly higher than that of the untreated PPy:PSS CE and are comparable with that of a Pt CE. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43772.     

Synthesis,characterization, and electrical properties of polypyrrole–bimetallic oxide composites

In this study, polypyrrole (PPy) and its bimetallic oxide composites (PPy–V₂O₅–MnO₂) were synthesized via a modified chemical oxidation polymerization method in the aqueous medium with FeCl₃·6H₂O as an oxidant. The synthesized materials were characterized with various analytical techniques to investigate their structural, crystallographic, thermal, morphological, optical, and electrical properties. The Fourier transform infrared study confirmed the successful synthesis of the materials, whereas the X-ray diffraction analyses showed the amorphous and crystalline natures of the PPy and PPy–V₂O₅–MnO₂ composites, respectively. The bimetallic oxide content improved the thermal stability of the composites, as ratified by thermal analysis. The synthesized PPy had a globular and spongy nature, whereas the composites were mixtures of short and long rod-shaped particles. The bimetallic oxide blend enhanced the doping, surface area and semiconducting nature of composites, and lower electrical resistance compared with those of the PPy. The resistance of the synthesized materials depended on the V₂O₅–MnO₂ blend content in the composites and the temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47680.     

Nano-composite of polypyrrole/modified mesoporous carbon for electrochemical capacitor application

Nano-thin polypyrrole (PPy) layers were coated on chemically modified ordered mesoporous carbon (m-CMK-3) by an in situ chemical polymerization. Structural and morphological characterizations of m-CMK-3/PPy composites were carried out using field emission scanning electron microscopy. Pseudo-capacitive behavior of the deposited PPy layers on m-CMK-3 was investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. As results of this study, the thin layer of PPy in the composite electrode was effective to obtain fully reversible and very fast Faradaic reaction. A maximum discharge capacity of 427 F g⁻¹ or 487 F g⁻¹ after correcting for weight percent of PPy phase at the current density of 5 mA cm⁻², could be achieved in a half-cell setup configuration for the m-CMK-3/PPy composites electrode, suggesting its potential application in electrode material for electrochemical capacitors.     

Electroconductive and catalytic performance of polypyrrole/montmorillonite/silver composites synthesized through in situ oxidative polymerization

The present study demonstrates a simple approach to the formation of polypyrrole/montmorillonite/silver (PPy/Mt/Ag) composites via in situ oxidative polymerization of pyrrole (Py) in the presence of AgNO₃ acting as a direct oxidant. The polymerization was performed in the presence of dodecylbenzenesulfonic acid, which acts as a stabilizing and doping agent. The morphological, structural, and thermal properties of PPy/Mt/Ag composites are discussed in detail and a possible formation mechanism is proposed. The electrical conductivities of the composites pressed at different pressing pressures were investigated using four‐probe analyzer. X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy results indicated the partially exfoliated structure of the composites and Fourier transforms infrared results suggested the strong interactions between Si? O? Si groups in Mt and N? H groups in PPy chains. The addition of Mt in the PPy polymer enhanced thermal property of the polymer. The conductivity of 1.08 S cm^?1 was observed in the sample with 20 wt % Mt loading and applied pressure of 5 MPa. The composites obtained in the present study catalyze the reduction of methylene blue by sodium borohydride, achieving 92% conversion of MB to colorless within a few minutes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45986.     

Synthesis of urethane acrylate based electromagnetic interference shielding materials

In this work, a new method, consists of synthesis of urethane acrylate (UA) followed by in situ polymerization of pyrrole using cerium (IV) as an oxidant and UV‐curing of the composites, for preparing polypyrrole–UA (PPy–UA) composite films was described. It appeared that dielectric constants of the composites increased with increasing the PPy content and decreased with increasing the frequency from 10^?2 to 10⁷, indicating an interfacial Maxwell–Wagner contribution to the permittivity. An incorporation of a small amount of PPy (15% Py) to UA matrix increased their dielectric constants more than 4 × 10⁴ (41,259) at 10^?2 Hz. So, the incorporation of PPy was very effective for enhancing the dielectric properties of UA matrix. Furthermore, the significant enhancement in dielectric properties (loss tangent and dielectric constant) contributes to the improvement in electromagnetic interference shielding efficiency. Composite films were characterized using Fourier transform infrared attenuated total reflectance (FTIR‐ATR) spectrophotometer and ¹H‐NMR. It was seen that PPy is blended with the UA matrix at the molecular level through H‐bonding interactions. A linear relationship was also observed between the characteristic groups' absorbances of PPy (from FTIR‐ATR) and dielectric constant values (from dielectric spectrometer). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Preparation and characterization of electrospun polyurethane–polypyrrole nanofibers and films

Polyurethane (PU)–polypyrrole (PPy) composite films and nanofibers were successfully prepared for the purpose of combining the properties of PU and PPy. Pyrrole (Py) monomer was polymerized and dispersed uniformly throughout the PU matrix by means of oxidative polymerization with cerium(IV) [ceric ammonium nitrate Ce(IV)] in dimethylformamide. Films and nanofibers were prepared with this solution. The effects of the PPy content on the thermal, mechanical, dielectric, and morphological properties of the composites were investigated with differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR)–attenuated total reflection (ATR) spectroscopy, dielectric spectrometry, and scanning electron microscopy. The Young's modulus and glass-transition temperatures of the composites exhibited an increasing trend with increases in the initially added amount of Py. The electrical conductivities of the composite films and nanofibers increased. The crystallinity of the composites were followed with DSC, the mechanical properties were followed with DMA, and the spectroscopic results were followed with FTIR–ATR spectroscopy. In the composite films, a new absorption band located at about 1650 cm⁻¹ appeared, and its intensity improved with the addition of Py. The studied composites show potential for promising applications in advanced electronic devices. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhanced adhesion of conductive coating on plasma‐treated polyester fabric: A study on the ageing effect

In recent years, there has been growing attention on intrinsically conducting polymers, such as polypyrrole (PPy) because of the wide range of possible applications. Adhesion to other materials is a pending problem that could be tackled by enhancing the chemical affinity of the surface toward PPy coating. In this work, low‐temperature plasma pretreatments were used for improving adhesion of PPy on polyester (PET) fabrics by changing the surface chemistry and generating a microscopically rough surface. Oxygen and argon plasmas were used to treat both sides of PET fabrics before PPy deposition by in situ chemical polymerization. Moreover, PPy depositions were performed 1 h, 1 week, and 1 month after the plasma treatments to study possible ageing effects. Different chemical/physical characterizations (contact angle, surface energy, atomic force microscopy, and X‐ray photoelectron spectroscopy) showed the efficacy of plasma pretreatments in inducing wettability on PET fabrics and promoting adhesion of the PPy layer. The enhanced adhesion was confirmed by abrasion tests and subsequent surface resistivity and color measurements. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Nitrogen-doped carbon coated palygorskite as an efficient electrocatalyst support for oxygen reduction reaction

An electrocatalyst support, nitrogen-doped graphitic layer (CN_x) coated palygorskite (PLS) (donated as PLS@CN_x), is synthesized by carbonizing the polypyrrole (PPy) coated PLS and is explored for the first time as a cathode electrocatalyst support in proton exchange membrane fuel cell. The structural and chemical properties of the PLS@CN_x are investigated by Fourier-Transform infrared spectrometer, thermogravimetric analysis, X-ray diffraction and transmission electron microscopy. The electrocatalytic activity and stability of Pt/PLS@CN_x toward oxygen reduction reaction (ORR) are studied by cyclic voltammetry (CV) and steady state polarization measurements. Upon loading Pt (20 wt%), the catalysts exhibit superior catalytic performance during ORR, surpassing the conventional Pt/C (Vulcan XC-72) catalysts. High electrocatalytic activity and good stability can be attributed to the nitrogen atom incorporation and SiO₂ component in PLS.