Preparation and electrochemistry of nanostructured PPy/graphite nanosheets/rare earth ions composites for supercapacitor

Highly conductive PPy/graphite nanosheets/rare earth ions (PPy/nanoG/RE³⁺) composites were prepared via in‐situ polymerization with p‐toluenesulfonic acid as a dopant and FeCl₃ as an oxidant. The microstructures of nanoG and PPy/nanoG/RE³⁺ were characterized by the SEM and TEM examinations. It was found that nanoG and PPy nanospheres formed the uniform composite with the PPy nanospheres embedded on the nanoG surface and/or filled between the nanoG. The effects of nanoG and RE³⁺ on the electrical conductivity and electrochemical performance of the composites were investigated. The results showed that the nanoG and RE³⁺ as the filler had effect on the conductivity and electrochemical performance of PPy/nanoG/RE³⁺ composites, which played an important role in forming a conducting network in PPy matrix. A specific capacitance of as high as 175 F/g at a current density of 1 A/g was achieved over the PPy/nanoG/Gd³⁺ composite. The capacitance of the PPy/nanoG/Gd³⁺ composite decreased only 5.1% after 800 charging/discharging cycles at a current density of 1 A/g. POLYM. ENG. SCI., 54:2731–2738, 2014. © 2013 Society of Plastics Engineers     

Synthesis,characterization and supercapacitors of electrically conductive PPy/graphene/rare earth ions composites

PPy/graphene/rare earth ions (PPy/GR/RE³⁺) were prepared using an in situ chemical polymerization of the monomer in the presence of FeCl₃ oxidant and p-toluenesulfonic acid dopant. The PPy/GR/RE³⁺ composites were characterized by FT-IR spectroscopy, four-point probe conductivity, scanning electron microscopy and transmission electron microscopy. The maximum conductivity of PPy/GR/Gd³⁺ composites is about 9.71 S/cm found with 1 wt% GR and 2 wt% Gd³⁺ at room temperature. The capacitance of the composite electrodes was investigated with cyclic voltammetry. As results of this study, the PPy/GR/Gd³⁺ was effective to obtain fully reversible and very fast faradaic reaction. Hence, the PPy/GR/Gd³⁺ could contribute to the pseudo-capacitive charge storage. The PPy/GR/Gd³⁺ exhibited higher specific capacitance of ~238 F/g at 1 A/g current density. Thermal gravimetric analysis demonstrates an improved thermal stability of PPy in the PPy/GR/Gd³⁺ composites.     

Synthesis of highly conductive PPy/graphene nanosheets/NiO composite using ultrasonic technique

Highly conductive polypyrrole/graphene nanosheets/NiO (PPy/GNS/NiO) composites are fabricated via ultrasound technique using p‐toluenesulfonic acid as a dopant and FeCl₃ as an oxidant. The effects of the GNS and NiO loading on the electrical conductivity are investigated. The maximum conductivity of PPy/GNS/NiO composites about 24.39 S/cm found with 3 wt% GNS and 48.7 wt% NiO at room temperature. The results showed that the high‐aspect‐ratio structure of GNS played an important role in forming a conducting network in PPy matrix. The microstructures of PPy/GNS/NiO are evidenced by the scanning electron microscope and transmission electron microscope examinations. The cyclic voltammetry curves can be seen that the PPy/GNS/NiO composites also have good electrochemical performance, and it can be used as a supercapacitor electrode material. POLYM. COMPOS., 34:997–1002, 2013. © 2013 Society of Plastics Engineers     

Polypyrrole coated graphene nanoplatelets and the effect of rare earth ions with nanocomposites

PPy/graphene/rare earth ions (PPy/GR/La³⁺, PPy/GR/Sm³⁺, PPy/GR/Eu³⁺, PPy/GR/Gd³⁺ and PPy/GR/Tb³⁺) are fabricated via in-situ polymerization using p-toluenesulfonic acid as a dopant and FeCl₃ as an oxidant. The surface morphology of the PPy/GR/La³⁺, PPy/GR/Sm³⁺, PPy/GR/Eu³⁺, PPy/GR/Gd³⁺ and PPy/GR/Tb³⁺ composites were characterized by using transmission electron microscopy. The maximum conductivity of PPy/GR/La³⁺, PPy/GR/Sm³⁺, PPy/GR/Eu³⁺, PPy/GR/Gd³⁺ and PPy/GR/Tb³⁺ composites found with 1 wt.% GR and 2 wt.% La³⁺, Sm³⁺, Eu³⁺, Gd³⁺ and Tb³⁺ at room temperature.     

PPy/Ni/NanoG复合材料的制备及导电性能研究

以聚吡咯（PPy）为基体,FeCl3作为氧化剂,十二烷基苯磺酸钠（DBSNa）作为掺杂剂,表面镀有金属镍(Ni)膜的纳米石墨微片（NanoG）作为二维层状纳米填料,通过原位聚合法制备了PPy/Ni/NanoG导电复合材料,并对其结构和导电性能进行了表征。结果表明,PPy与Ni/NanoG的相容性较好,PPy聚合物均匀地包覆在Ni/NanoG片层表面和边缘;Ni/NanoG的二维受限空间的阻隔作用能够有效抑制PPy分子链的卷曲和交联,使PPy分子链共轭程度提高,π电子的离域性增加;循环伏安测试表明复合材料的峰面积大,峰电流高,导电能力强;复合材料的导电性能随Ni/NanoG含量的增加由8.2 S/cm提高到103.6 S/cm,Ni/NanoG的阈值为2 %（质量分数,下同）。     

Preparation of polystyrene–graphite conducting nanocomposites via intercalation polymerization

In situ polymerization of styrene was conducted in the presence of expanded graphite obtained by rapid heating of a graphite intercalation compound (GIC), to form a polystyrene–expanded graphite conducting composite. The composite showed excellent electrically conducting properties even though the graphite content was much lower than in normal composites. The transition of the composite from an electrical insulator to an electrical semiconductor occurred when the graphite content was 1.8 wt%, which is much lower than that of conventional conducting polymer composites. TEM, SEM and other studies suggest that the graphite was dispersed in the form of nanosheets in a polymer matrix with a thickness of 10–30 nm, without modification of the space between carbon layers and the structure of the graphite crystallites. The composite exhibited high electrical conductivity of 10^?2 S cm^?1 when the graphite content was 2.8–3.0 wt%. This great improvement of conductivity could be attributed to the high aspect ratio (width‐to‐thickness) of the graphite nanosheets. The rolling process strongly affected the conductivity and the mechanical properties of the composite. © 2001 Society of Chemical Industry     

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     

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.     

Novel Ni/polypyrrole and Cu/polypyrrole composites prepared in the presence of different acids: Synthesis and investigation of thermal stability

We report the synthesis and characterization of new organic/inorganic hybrid materials constituted of Ni(0) and Cu(0) nanoparticles and polypyrrole (PPy). Copper and nickel nanoclusters were synthesized by a chemical reduction of aqueous metal salt solutions by sodium borohydride. PPy/Ni(0) and PPy/Cu(0) composites were obtained in the presence of two different acids (H₃BO₃, CH₃COOH), by polymerizing pyrrole‐Ni and pyrrole‐Cu particles by using iron (III) chloride. The composites have been characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and magnetic susceptibility techniques. Conductivity measurements of samples were taken using four‐probe devices. The PPy/Ni(0) and PPy/Cu(0) nanocomposites doped with different acids exhibited higher conductivity values than those of homopolymers. Among all samples, Ni/PPy‐H₃BO₃ has the highest conductivity (1.42 S cm^?1). Homopolymers and composites showed a stable and increasing conductivity with increasing temperature, except Ni(0). We observed that from TGA analysis of polymers, metal composites of PPy synthesized in two different media are more stable than those of PPy‐CH₃COOH and PPy‐H₃BO₃. The magnetic susceptibility values of homopolymers and Cu are negative, whereas the other samples are positive. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Electrically conducting biodegradable polymer composites (polylactide‐polypyrrole and polycaprolactone‐polypyrrole) for passive resonant circuits

Electrically conducting biodegradable polymer composites made of polypyrrole (PPy) nanoparticles embedded in poly(L ‐lactide) (PLLA) or poly(ε‐caprolactone) (PCL) are prepared by chemical oxidative polymerization. They will be used as electrical conductors for fabricating biodegradable passive resonant circuits for bioimplants. For both composites, the conductivity exhibits a percolation threshold at ～6 wt% of PPy. Several reactants are tested, the polymerization process resulting in the highest conductivity uses iron(III)chloride hexahydrate (FeCl₃), sodium dodecyl benzene sulfonate, and p‐nitrophenol (pNPh), for both poly(L ‐lactide)‐polypyrrole (PLLA‐PPy) and poly(ε‐caprolactone)‐polypyrrole (PCL‐PPy). Conductivities of 2.7 ± 0.8 S cm^ε1 (PLLA‐PPy) and 7.8 ± 2.3 S cm^?1 (PCL‐PPy) are reached for a PPy content of 40 wt%. The PPy particle, observed by SEM, forms agglomerates having a size of 0.6–3.5 μm. The samples have similar PPy particle distributions over the entire cross sections. The conductivity as a function of time is investigated, being 34–70% of the initial value for samples stored in nitrogen, whereas it is less than 1% for samples stored in body‐like conditions, bringing the conclusion that a biodegradable packaging will be required to protect the resonant circuits from body fluids. Finally, the biocompatibility of the polymer composites is evaluated with cytocompatibility tests on dermal human fibroblast cells, showing promising results in particular for composites having a low PPy content. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Synthesis and characterization of secondary doped polypyrrole/organic modified attapulgite conductive composites

Secondary doping method was introduced into fabricating polypyrrole/oganic modified attapulgite conductive composites. The preparation conditions, such as amount of hexadecylpyridinium chloride (CPC, modifying agent), organic modified attapulgite (OATP), and HCl (secondary dopant) have been optimized to get the composites with the highest conductivity. When m_CPC/m_ATP, m_OATP/m_Py, and n_HCl/n_SA (SA is sulfamic acid) reaches 0.03, 0.6, and 0.5, respectively, the PPy/OATP composites possess the highest conductivity of 87.59 S cm^?1 as well as the highest thermal degradation temperature of 249.29°C. Scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, UV‐Visible diffuse reflectance study, and X‐ray photoelectron Spectroscopy results showed that PPy chains form the core‐shell structure and may combine with OATP via π–π stacking interaction. Thermogravimetric analysis showed that the thermal stability of PPy/OATP‐SH composites was enhanced and these could be attributed to the retardation effect of OATP as barriers for the degradation of PPy. This method may open a new door for PPy‐based composites with special structures, higher performance, and thus broader application ranges. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41407.     

Supercritical carbon dioxide assisted preparation of conductive polypyrrole/cellulose diacetate composites

Supercritical carbon dioxide (SC‐CO₂) has been used to assist the preparation of conductive polypyrrole/cellulose diacetate (PPy/CDa) composites by in situ chemical oxidative polymerization. The morphology and conductivity of resulted composites were investigated with scanning electron microscopy and four‐probe method, respectively. With the assistance of strong swelling effect of SC‐CO₂, composite films were obtained with a macroscopically homogeneous structure and conductivity up to 10^?1 S cm^?1 order of magnitude. Increasing the pressure of SC‐CO₂ increased conductivity, while increasing the temperature decreased conductivity. For comparison, PPy/CDa composite was also prepared with conventional oxidative method in aqueous solution. From the viewpoint of conductivity and environmental protection, the SC‐CO₂ method showed its superiority over the conventional one. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4575–4580, 2006     

Preparation and characterization of conductive and magnetic PPy/Fe3O4/Ag nanocomposites

In this article, conductive and magnetic nanocomposites composed of polypyrrole (PPy), magnetite (Fe₃O₄) nanoparticles (NPs), silver (Ag) NPs, have been successfully synthesized with a two step process. First, the PPy/Fe₃O₄ was prepared by the ultrasonic in situ polymerization. Next, the PPy/Fe₃O₄/Ag was synthesized through the electrostatic adsorption. The products were characterized by fourier‐transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Thermogravimetric (TG), conductivity and magnetization analysis, and the results showed that the Ag NPs with the good conductivity coated uniformly on the surface of PPy/Fe₃O₄ and improved the conductivity of PPy/Fe₃O₄/Ag composites. In addition, as compared with PPy/Fe₃O₄, PPy/Fe₃O₄/Ag composites also have the excellent electro‐magnetic property and enhanced thermostability. POLYM. COMPOS., 35:450–455, 2014. © 2013 Society of Plastics Engineers     

Fabrication of carbon nanotubes/polypyrrole/carbon nanotubes/melamine foam for supercapacitor

The carbon nanotubes (CNTs) have been loaded on the melamine foam (MF) to form the composite (CNTs/MF) by dip‐dry process, then polypyrrole (PPy) is coated on CNTs/MF (PPy/CNTs/MF) through chemical oxidation polymerization by using FeCl₃·6H₂O adsorbed on CNTs/MF as oxidant to polymerize the pyrrole vapor. Finally, CNTs are coated on the surface of PPy/CNTs/MF to increase the conductivity of the composite (CNTs/PPy/CNTs/MF) by dip‐dry process again. The composites have been characterized by X‐ray diffraction spectroscopy, scanning electron microscopy and electrochemical method. The results show that the structure of the composites has obvious influence on their capacitive properties. According to the galvanostatic charge/discharge test, the specific capacitance of CNTs/PPy/CNTs/MF is about 184 F g^?1 based on the total mass of the composite and 262 F g^?1 based on the mass of PPy (70.2 wt % in the composite) at the current density of 0.4 A g^?1, which is higher than that of PPy/CNTs/MF (120 F g^?1 based on the total mass of the composite and 167 F g^?1 based on the mass of the PPy). Furthermore, the capacitor assembled by CNTs/PPy/CNTs/MF shows excellent cyclic stability. The capacitance of the cell assembled by CNTs/PPy/CNTs/MF retains 96.3% over 450 scan cycles at scan rate of 20 mV s^?1, which is larger than that assembled by CNTs/PPy/MF (72.5%). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39779.     

Multiwalled carbon nanotubes/polypyrrole/graphene/nonwoven fabric composites used as electrodes of electrochemical capacitor

The reduced graphene oxide/nonwoven fabric (rGO/NWF) composites have been fabricated through heating the NWF coated with the mixture of GO and HONH₂·HCl at 130°C, during which the GO is chemically reduced to rGO. Then the composites of polypyrrole (PPy)/rGO/NWF have been prepared through chemically polymerizing pyrrole vapor by using the FeCl₃·6H₂O adsorbed on rGO/NWF substrate as oxidant. Finally, multiwalled carbon nanotubes (MWCNTs) are used as conductive enhancer to modify PPy/rGO/NWF through dip‐dry process to obtain MWCNTs/PPy/rGO/NWF. The prepared composites have been characterized and their capacitive properties have been evaluated in 1.0M KCl electrolyte by using two‐electrode symmetric capacitor test. The results reveal that MWCNTs/PPy/rGO/NWF possesses a maximum specific capacitance (C_sc) of about 319 F g^?1 while PPy/rGO/NWF has a C_sc of about 277.8 F g^?1 at the scan rate of 1 mV s^?1 and that optimum MWCNTs/PPy/rGO/NWF retains 94.5% of initial C_sc after 1000 cycles at scan rate of 80 mV s^?1 which is higher than PPy/rGO/NWF (83.4%). Further analysis reveals that the addition of MWCNTs can increase the charger accumulation at the outer and inner of the composites, which is favorable to improve the stability and the rapid charge‐discharge capacity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41023.     

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     

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.     

In-situ synthesis and characterization of electrically conductive polypyrrole/graphene nanocomposites

Polypyrrole (PPy)/graphene (GR) nanocomposites were successfully prepared via in-situ polymerization of graphite oxide (GO) and pyrrole monomer followed by chemical reduction using hydrazine monohydrate. The large surface area and high aspect ratio of the in-situ generated graphene played an important role in justifying the noticeable improvements in electrical conductivity of the prepared composites via chemical reduction. X-ray photoelectron spectroscopy (XPS) analysis revealed the removal of oxygen functionality from the GO surface after reduction and the bonding structure of the reduced composites were further determined from FTIR and Raman spectroscopic analysis. For PPy/GR composite, intensity ratio between D band and G band was high (∼1.17), indicating an increased number of c-sp² domains that were formed during the reduction process. A reasonable improvement in thermal stability of the reduced composite was also observed. Transmission electron microscopy (TEM) observations indicated the dispersion of the graphene nanosheets within the PPy matrix.     

Preparation of the flexible polypyrrole/polypropylene composite fibrous film for electrochemical capacitor

Polypyrrole (PPy)/polypropylene fibrous membrane (PPF) composite materials with different PPy contents are prepared through in situ chemical oxidation polymerization in the pyrrole atmosphere at room temperature by dissolving the FeCl₃·6H₂O in methanol and acetonitrile as oxidant. The morphology of the composite is examined by scanning electron microscope (SEM), the conductivities of the composites are measured by convenient four‐probe method, and the properties of the capacitor cells assembled by the obtained PPy/PPF are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS) measurements. The results show that the morphology, conductivity, and the capacitor property of the composite are influenced strongly by the solvent of the oxidant. The capacitor assembled by the PPy/PPF prepared by using acetonitrile as the solvent for FeCl₃^.6H₂O can adapt for quick charge/discharge, and exhibit the highest capacitance of about 72.5 F g^?1 when the PPy content is about 8.0%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Synthesis and properties of conducting polypyrrole,polyalkylanilines, and composites of polypyrrole and poly(2‐ethylaniline)

Conducting polymers of alkylanilines, pyrrole, and their conducting composites were synthesized by oxidation polymerization. The oxidants used were KIO₃ and FeCl₃ for the polyalkylanilines and polypyrrole (PPy), respectively. Among the polyalkylanilines synthesized with KIO₃ salt, the highest conductivity was obtained with poly(2‐ethylaniline) (P2EAn) with a value of 4.10 × 10^?5 S/cm. The highest yield was obtained with poly(N‐methylaniline) with a value of 87%. We prepared the conducting composites (PPy/P2EAn and P2EAn/PPy) by changing synthesis order of P2EAn and PPy. The electrically conducting polymers were characterized by IR spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, and X‐ray diffraction spectroscopy. From the results, we determined that the properties of the composites were dependent on the synthesis order of the polymers. The thermal degradation temperature of PPy was observed to be higher than that of the other polymers and composites. We determined from X‐ray results that the structures of the homopolymers and composites had amorphous regions (88–95%) and crystal regions (5–12%). From the Gouy balance magnetic measurements, we found that the polymers and composites were bipolaron conducting mechanisms. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 241–249, 2006