Preparation and characterization of polypyrrole/clinoptilolite nanocomposite with enhanced electrical conductivity by surface polymerization method

In this work, polypyrrole/clinoptilolite nanocomposite was synthesized by in situ surface polymerization of pyrrole using Fe³⁺ as oxidant, incorporated on the inner and outer surface of clinoptilolite nanoparticles. Formation of nanocomposite and deposition of polypyrrole on the clinoptilolite surface was confirmed and characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) patterns, scanning electron microscopy (SEM), and cyclic voltammetry techniques. Elemental analysis showed the loading/incorporation of 9.18 wt% polypyrrole in the clinoptilolite structure. However the electrical conductivity of polypyrrole/clinoptilolite nanocomposite pellets was higher than that of similar pure polypyrrole pellets, synthesized through the chemical oxidation polymerization method using Fe³⁺ as oxidant without the presence of clinoptilolite nanoparticles. Improved structural order or crystalinity of polypyrrole chains in nanocomposite structure which was confirmed by XRD and SEM results, may be the responsible of higher electrical conductivity of nanocomposite compared to pure polypyrrole although the low content (9.18 wt%) of polypyrrole in nanocomposite. Cyclic voltammetry studies showed that polypyrrole/clinoptilolite nanocomposite is electroactive similar to pure polypyrrole. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

合成工艺对聚吡咯电导率及可溶性的影响

研究了聚吡咯(PPy)的化学氧化合成，制得了粉末状的聚吡咯样品，并对样品进行了表征。讨论了合成温度、添加剂、氧气对聚吡咯电导率的影响以及聚吡咯的可溶性问题。实验表明：低温、无氧气存在和加入聚乙二醇(PEG)等合成条件有利于电导率的提高；在有十二烷基苯磺酸(DBSA)存在的情况下，聚吡咯可溶于间甲酚。     

聚吡咯/有机蒙脱土纳米复合材料的制备及其导电性

采用三氯化铁作氧化剂,对甲苯磺酸钠作掺杂剂,使插入十六烷基三甲基溴化铵改性的有机蒙脱土层间的吡咯发生氧化聚合,制备了导电性优异的聚吡咯／有机蒙脱土纳米复合材料。结果表明,试样的电导率最高可达到8．50S／cm。XRD测试表明,蒙脱土层间距由1．22nm增加到4．50nm。     

Synthesis and characterization of soluble polypyrrole with improved electrical conductivity

Polypyrroles doped with two dopants were prepared by chemical polymerization in aqueous solutions of pyrrole monomer. The solutions contained dodecylbenzenesulfonic acid (DBSA) as a dopant, tetraethylammonium tetrafluoroborate (TEABF₄) as a codopant, and ammonium persulfate (APS) as an oxidant. The PPy composites [polypyrrole‐dodecylbenzenesulfonates (PPy‐DBS) codoped with tetrafluoroborate (BF)—PPy‐DBS‐BF] were soluble in m‐cresol, NMP, and conditionally soluble in chloroform. Cyclic voltammetry was measured to know the electrochemical property of PPy‐DBS‐BF. The maximum electrical conductivity of room temperature for PPy‐DBS‐BF is 1.18 s/cm, which is greatly higher than that of polypyrrole doped with DBS^? (0.04 s/cm). The composition and structural characterization of PPy‐DBS‐BF were inferred from elemental analysis, nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Scanning electron microscopy was performed to know the morphology of PPy‐DBS‐BF. The results of UV‐Vis spectra and electron spin resonance measurements showed that polaron and bipolaron existed as charge carrier of soluble PPy‐DBS‐BF. From the temperature dependence of the electrical conductivity, it was suggested that possible conduction mechanism for soluble PPy‐DBS‐BF should be hopping conduction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2583–2590, 2002     

Fabrication of polypyrrole/graphene oxide nanocomposites by liquid/liquid interfacial polymerization and evaluation of their optical,electrical and electrochemical properties

A novel route has been developed to synthesize polypyrrole (PPy)/graphene oxide (GO) nanocomposites via liquid/liquid interfacial polymerization where GO and initiator was dispersed in the aquous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), ultraviolet–visible absorption (UV–vis), X-ray diffraction (XRD), electrochemical and electrical conductivity measurements. A good dispersion of the GO sheets within the PPy matrix was observed from the morphological analysis. The composites exhibited noticeable improvement in thermal stability and electrical conductivity in comparison to pure polypyrrole. The composites showed excellent electrochemical reversibility at the scan rate of 0.1 V/s and good cyclic stability even up to 100th cycle. Newly developed graphene oxide based polypyrrole composite could be applied in electrochemical energy storage device.     

Effects of carbon nanotubes and interphase properties on the interfacial conductivity and electrical conductivity of polymer nanocomposites

L_c is the minimum length of carbon nanotubes (CNTs) required for efficient transfer of filler conductivity to polymer matrix in polymer CNT nanocomposites (PCNTs). In this work, L_c is correlated with the dimensions of the CNTs and the interphase thickness. Subsequently, the interfacial conductivity as well as the effective length and concentration of CNTs are expressed by CNT and interphase properties. Moreover, a simple model for the tunneling conductivity of PCNTs is developed with these effective terms. The impacts of all parameters on L_c, the interfacial conductivity, the fraction of CNTs in the networks and the conductivity of the PCNT are explained and justified. In addition, the predictions of the percolation threshold and conductivity are compared with the experimental results of several samples. The desirable values of interfacial conductivity are achieved by thin, short and super‐conductive CNTs, high waviness and a thick interphase. However, thin and long CNTs, low waviness, a thick interphase, poor tunneling resistivity due to the polymer matrix and a short tunneling distance advantageously affect the conductivity of PCNTs, because they produce large conductive networks. The predictions also show good agreement with the experimental measurements of percolation threshold and conductivity, which confirms the developed equations. © 2020 Society of Chemical Industry     

Structural and optical properties of self-assembled polypyrrole nanotubes

Polypyrrole (PPy) nanotubes doped with camphorsulfonic acid (CSA) have been synthesized using self-assembly polymerization method. The average diameter of the resulting PPy nanotubes has been controlled by varying the dopant/monomer molar ratio. Formation mechanism of PPy nanotubes has been discussed at length. The formation of PPy nanotubes has been confirmed from the high resolution transmission electron microscopy (HRTEM) studies. FTIR studies depict that the “effective conjugation length” of PPy nanotubes increases with increasing CSA/Py molar ratio. UV-vis studies reveal the formation of polaron and bipolaron bands within the band gap of neural PPy, confirming the doping of PPy nanotubes with CSA. The optical band gap energy decreases with increasing CSA/Py ratio and also the thermal stability of PPy nanotubes gets enhanced with increasing dopant/monomer molar ratio.     

Interfacial synthesis of polypyrrole/graphene composites and investigation of their optical,electrical and electrochemical properties

We report the development of a novel route for the synthesis of polypyrrole/graphene (PPy/GR) composites by liquid ? liquid interfacial polymerization, where GR and the initiator were dispersed in the aqueous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, X‐ray diffraction, thermogravimetric analysis, electrochemical and electrical conductivity measurements. Structural analysis reveals a uniform dispersion of GR sheets in the PPy matrix. The composites showed noticeable improvement in thermal stability and electrical conductivity (8.45 S cm^?1) and excellent electrochemical reversibility in comparison with pure PPy. A specific capacitance of 260 F g^?1 at a current density of 100 mA g^?1 was achieved for the composite during the charge–discharge process. © 2013 Society of Chemical Industry     

Chemically oxidized polypyrrole: Influence of the experimental conditions on its electrical conductivity and morphology

The effect of synthesis conditions on the electrical conductivity and the morphology of a chemically oxidized polypyrrole was investigated. It was found that the electrical conductivity of polypyrrole was strongly dependent on the pyrrole/FeCl₃ ratio, which controls the redox potential of the reaction medium. The reaction temperature and the reaction duration also influence the electrical conductivity of the polypyrrole. A considerable influence of the nature of the solvent used on the aggregation state of polypyrrole particles was demonstrated. Optimal experimental conditions are proposed.     

Structural evolution of non-isothermally formed dysprosium sesquioxide nanoparticles and their optical and electrical conductivity properties

This paper describes the utilization of dysprosium acetate non-isothermal decomposition as a route for Dy₂O₃ nanoparticles preparation. Thermal events emerging during the heat treatment of dysprosium acetate was monitored using thermogravimetric analysis (TGA). The structural properties of the various solids obtained at the temperature range of 200–900 °C were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). It was found that 700 °C adequate for both the complete precursor decomposition and the crystallization process of the desired Dy₂O₃ nanoparticles. The morphology of the obtained Dy₂O₃ nanoparticles was examined by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Photo Luminescence (PL) was used for investigating the optical features of the obtained Dy₂O₃ nanoparticles. Moreover, the electrical conductivity of these nanoparticles has been investigated in the temperature range of 200–500 °C.     

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     

聚吡咯/硫化镉的制备及其光学性能研究

将聚吡咯和纳米粒子结合起来制备的复合材料兼具了导电高分子材料、无机半导体材料的优势,与此同时这种的复合材料还具有显著的三阶非线性光学性质。本文拟采用界面氧化聚合法制备聚吡咯膜,通过实验发现反应的最佳溶剂为三氯甲烷,最佳的氧化剂为过硫酸铵。当聚吡咯于过硫酸铵反应浓度均为0.15 mol/L左右时可以生成表面平整、厚度适中、力学性能较好的聚吡咯膜。通过将上述方法制备的聚吡咯膜先浸泡在醋酸镉溶液中吸附Cd2+,最后与硫代乙酰胺处理得到PPy/CdS复合材料。本实验采用了探针式表面轮廓仪分析、扫描电镜(SEM)、傅立叶红外光谱(FTIR)、X-射线衍射(XRD)、Z-扫描测试法、热重(TG)分析等对产物进行表征。结果表明,聚吡咯/硫化镉纳米复合材料上纳米粒子的分布状况及粒子大小与掺比浓度有关,浓度越低分布越密、粒子直径越小,当聚吡咯、硫化镉的掺杂比达到1:0.001时粒子直径可达20 nm左右。此外,复合了硫化镉纳米粒子后聚吡咯的热稳定性提高了33.3%。由Z-扫描结果显示PPy/CdS具有很强的三阶非线性特性。     

The electrical conductivity and optical reflectance of graphite-SbF5 compounds

Graphite intercalation compounds were prepared from pyrolytic graphite and SbF₅ or SbF₅-HF mixtures. The compounds were characterized by c-axis thickness increase, gravimetric and X-ray analysis, and in some cases by elemental analysis. Measurements were made of the room temperature, basal-plane, electrical conductivity and the optical reflectance from 0.07 to 2.0 eV. The results of these measurements show clearly that the optical reflectance data for these materials is not amenable to analysis by a simple Drude model and that the maximum a-axis conductivity is approx. $\text{1}\text{3}$ that of copper.     

Effect of electrical properties on gas sensitivity of polypyrrole/cds nanocomposites

In the present work, polypyrrole (PPy) nanocomposites were synthesized using ferric chloride (FeCl₃) as an oxidant by in situ polymerization at room temperature. Cadmium sulfide (CdS) nanoparticles were synthesized by ultrasonication technique with size ranging between 60 and 110 nm. The PPy/CdS nanocomposites were prepared by taking 1–3 wt % loading of CdS to measure the electrical conductivity. The PPy nanocomposites were characterized by using FTIR, X‐ray diffraction, UV, and SEM. Furthermore, these PPy/CdS nanocomposites were investigated to study their effect of electrical properties on gas sensitivity of ammonia and LPG. The nanocomposites showed improvement in conductivity and sensing response toward 250 ppm NH₃ was found to be maximum (4.2) compared with 100 and 500 ppm NH₃ gas, whereas in the case of LPG, it showed sensitive response. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42379.     

Thermal,stability, morphological,and conductivity characteristics of polypyrrole prepared in aqueous medium

The aqueous polymerization of pyrrole with varying FeCl₃/Py mol ratio produces black insoluble powders. IR characterization reveals the shifting of the N? H stretching band to higher frequency with increasing FeCl₃ amount in the feed composition due to lowering of intermolecular H-bonding. SEM shows a spongy texture of the polymer. TGA indicates the initial decomposition temperatures (180°–237°C) to be somewhat dependent on the FeCl₃/Py feed ratio. DSC suggests the glass-transition temperature to be in the range 160–170°C for the polymers prepared with various feed compositions. The conductivity is also dependent on the FeCl₃/Py feed composition and levels off at a value of ～3 ohm^?1cm^?1. © 1994 John Wiley & Sons, Inc.     

Structural,mechanical, and electrical properties of electropolymerized polypyrrole composite films

Electrochemical polymerization of pyrrole in a solution containing dissolved poly(vinyl alcohol) (PVA) produces a homogeneous, free‐standing, flexible, and conductive polymer film. The films were characterized using infrared spectroscopy, wide‐angle X‐ray diffraction analysis, and scanning electron microscopy. The appearance of standard and some new absorption bands for polypyrrole (PPy) and PVA confirms the composite formation. The mechanical properties of conducting PVA + PPy films were studied and found to be improved with respect to the control PPy films. The electrical conductivity of the PVA + PPy films was measured by using standard four‐ and two‐probe methods. The conductivity of the films was found to depend on the pyrrole content. These conducting composites were further used as gas sensors by observing the change in current with respect to ammonia gas. It was observed that the current decreases when these composites were exposed to ammonia gas. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2511–2517, 2001     

Influence of processing parameters on the electric conductivity and on the mechanical properties of thick polypyrrole films

The electric conductivity and the mechanical properties of electrochemically synthesized polypyrrole/p‐toluene sulfonic acid (PPy/pTSA) as a function of its processing parameters were investigated. The influence of polymerization current density, pyrrole concentration, and counter ion concentration on the electric conductivity of thick (?100 μm) polymer films was examined and the electric conductivity was found to be in a range between 1.6 and 97 S · cm^?1. Analysis of the polymer's chemical composition delivered a result in agreement with literature data of one counter ion for every 2.97 pyrrole rings for the best conducting samples. In mechanical tests, maximum values for Young's modulus, tensile strength, and elongation at break, were found to be 4.0 GPa, 72.6 MPa, and 11.2%, respectively. POLYM. ENG. SCI., 47:662–666, 2007. © 2007 Society of Plastics Engineers.     

Influence of the dopant on the polypyrrole moisture content: Effects on conductivity and thermal stability

Having in mind to produce electrically conductive carbon–epoxy composite materials, we have filled an insulating epoxy resin with an electronic conducting polymer, polypyrrole (PPy). To select the PPy that best suits this process, various PPys were chemically synthesized. The syntheses were performed in water via a dispersion polymerization route using, initially, either FeCl₃ (PPy–Cl⁻) or (NH₄)₂S₂O₈ (PPy–HSO₄⁻) as oxidizing agents. Then, using (NH₄)₂S₂O₈ as the oxidant, two other PPy doped with aromatic species were obtained due to the dissolution of paratoluenesulfonic acid (PPy–TS⁻) or naphtalenesulfonic acid (PPy–NS⁻) in the reaction media. The characterization of the PPy samples by conductivity measurements, together with elemental and thermal analysis, showed that PPy–TS⁻ exhibits the highest conductivity and thermal stability, with the conductivity remaining steady over 14 days. In addition, a stabilizing effect of the aromatic anions was observed. The experiments have shown that moisture in the PPy cannot be entirely removed and that, with increasing moisture content, the conductivity also increases, indicating an ionic conductivity superimposed on the electronic conductivity usually observed in PPy. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1567–1577, 1998     

Effects of silver impurity on the structural,electrical, and optical properties of ZnO nanowires

1, 3, and 5 wt.% silver-doped ZnO (SZO) nanowires (NWs) are grown by hot-walled pulsed laser deposition. After silver-doping process, SZO NWs show some change behaviors, including structural, electrical, and optical properties. In case of structural property, the primary growth plane of SZO NWs is switched from (002) to (103) plane, and the electrical properties of SZO NWs are variously measured to be about 4.26 × 10⁶, 1.34 × 10⁶, and 3.04 × 10⁵ Ω for 1, 3, and 5 SZO NWs, respectively. In other words, the electrical properties of SZO NWs depend on different Ag ratios resulting in controlling the carrier concentration. Finally, the optical properties of SZO NWs are investigated to confirm p-type semiconductor by observing the exciton bound to a neutral acceptor (A⁰X). Also, Ag presence in ZnO NWs is directly detected by both X-ray photoelectron spectroscopy and energy dispersive spectroscopy. These results imply that Ag doping facilitates the possibility of changing the properties in ZnO NWs by the atomic substitution of Ag with Zn in the lattice.