Effect of dopant and oxidant on the electrochemical properties of polyaniline/graphite nanoplate composites

Optimizing the synthesis parameters of polyaniline/graphite nanoplate (PANI/GNP) composite is essential to the final electrochemical performance. Herein, the electrochemical properties of PANI/GNP composites, prepared by in situ chemical polymerization using varying amounts of different oxidants, with or without the addition of 4‐dodecylbenzenesulfonic acid (DBSA) as dopant, were investigated. Cyclic voltammetric results suggested that a stoichiometric amount of the oxidant iron chloride (FeCl₃) was beneficial to the electrochemical properties of the composites. The use of ammonium persulfate (APS) instead of FeCl₃ as oxidant largely increased the actual PANI content, conductivity and specific capacitance of the PANI/GNP composites. The dopant DBSA increased the conductivity of the PANI/GNP composites but did not show a positive effect on the electrochemical behavior. The cyclic voltammograms of the PANI/GNP composites indicated that the pseudocapacitance of PANI contributes more than the electrical double‐layer capacitance of GNP to the capacitance of the composites, while the presence of GNP plays an essential role in the rate capability of the composites. In this study, PANI/GNP (1:1) composite synthesized with an APS to aniline molar ratio of 1 showed a balanced combination of high specific capacitance (180.5 F g^?1 at 20 mV s^?1) and good rate capability (78% retention at 100 mV s^?1). © 2018 Society of Chemical Industry     

Electrically conductive carbon nanopipe-graphite nanosheet/polyaniline composites

Carbon nanopipe (CNP)–graphite nanosheet (GNS)/polyaniline (PANI) composites are synthesized by in situ chemical oxidative polymerization. The structural analysis (electron microscopy, Raman and X-ray diffraction) reveal that PANI is uniformly coated on both CNP and GNS structures resulting in the formation of a network of uniform composite structures. Thermogravimetric analysis shows that CNP–GNS/PANI composites are thermally stable up to 300 °C; the polymeric backbone degrades above 300 °C. CNP–GNS/PANI composites doped with m-cresol, a mixture of camphor sulfonic acid (CSA) and chloroform, and a mixture of CSA and m-cresol are electrically conductive. The electrical conductivity strongly depends on the dopants and about six orders of variation in conductivity can be achieved through the choice of the dopant.     

Polyaniline–13X zeolite composite‐supported platinum electrocatalysts for direct methanol fuel cell applications

We successfully synthesized 13X zeolite using a hydrothermal method. Then, composites of polyaniline (PANI) with 13X zeolite and PANI–13X with platinum were prepared by chemical oxidative polymerization and chemical reduction, respectively. Field emission scanning electron microscopy, X‐ray diffraction, Raman spectroscopy and Brunauer–Emmett–Teller techniques were used to characterize the PANI–Pt and PANI–Pt–13X composites. Further, the electrocatalytic activity towards methanol oxidation of the synthesized catalysts was explored using cyclic voltammetry in 1 mol L^?1 CH₃OH + 0.5 mol L^?1 H₂SO₄ solution. From the obtained results, PANI–Pt–13X shows superior performance compared to PANI–Pt towards methanol oxidation and electrical conductivity. Hence, the 13X zeolite‐incorporated PANI–Pt composite could be an efficient catalyst for direct methanol fuel cell applications. © 2019 Society of Chemical Industry     

The influence of single-walled carbon nanotube functionalization on the electronic properties of their polyaniline composites

The “in situ” preparation and characterization of composites of polyaniline (PANI) and single-walled carbon nanotubes (SWCNTs) are reported. To improve the dispersion and compatibility with the polymer matrix the raw SWCNTs were modified following different routes. SWCNTs oxidized by chemical or thermal treatments (nitric acid and air oxidation, respectively) were subjected to covalent functionalization with octadecylamine (ODA). SWCNT/PANI composites were prepared either from just oxidized SWCNTs, or from ODA functionalized SWCNTs. Temperature-programmed desorption, elemental analyses, ultraviolet-visible (UV-vis), UV-vis with near infrared and Raman spectroscopy, X-ray diffraction, scanning and transmission electron microscopy and conductivity measurements were used to characterize the functionalized SWCNT materials, dispersions and composites. The PANI composite prepared from air oxidized SWCNTs showed the best electrical conductivity indicating a better interaction with polyaniline than ODA functionalised SWCNTs. The improvement of conductivity is attributed to the doping effect or charge transfer of quinoide rings from PANI to SWCNTs.     

Polyaniline-graphene composites with a three-dimensional array-based nanostructure for high-performance supercapacitors

The ordered three-dimensional arrays conjugative polyaniline–graphene composites were fabricated through in-situ chemical oxidative polymerization of aniline in the presence of amino-functionalized graphene sheets (AFG), in which polyaniline (PANI) polymerization is initiated by those amino groups on graphene. Therefore, the resulting PANI nanorod arrays are integrated into a large conjugative frame based on chemical covalent bond incorporation. The structure and properties of these resulting composites were characterized and evaluated by combining Fourier transform infrared spectroscopy, Ultraviolet–visible absorption spectroscopy, Raman spectroscope, X-ray diffraction spectroscopy analyses and electrochemical techniques. Morphology was studied by scanning electron microscopy. It was found that the density and size of ordered PANI nanorod arrays can be manipulated by simply varying the amount of AFG. Such resultant composite exhibits high special capacitance, together with low electrical resistance and excellent cycling stability attributed to conjugative covalent bonds and ordered PANI nanorod arrays. Meanwhile, a new time-dependent heterogeneous nucleation mechanism was proposed and investigated in detail.     

A novel conductivity composite based on polyaniline/zirconium phenylphosphonate

A novel conductivity composite from polyaniline (PANI) and layered zirconium phenylphosphonate (ZrPP) was carried out through in situ chemical oxidation polymerization by the addition of an appropriate amount of ammonium peroxodisulfate solution, and the relevant structure and properties were investigated. The composites were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. The electrical conductivity was measured by the four‐probe technique. The electrical conductivity of the composites improved with increasing ZrPP loading, and the materials had reasonably good electrical properties, even with 40 wt % loadings of ZrPP in the polymer matrix. The results reveal that π–π interaction was formed in the composites, which enhanced the electrical conductivity of the composites compared to that in neat PANI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of processible doped polyaniline‐polyacrylic acid composites

Processible composites of emeraldine salt form of polyaniline (PANI) with polyacrylic acid (PAA) are synthesized and studied for their structural, electrical, mechanical, thermal, and electrochemical properties. The processible conducting composites of various weight percentage from 20 wt % to 90 wt % (of PANI) have been prepared by mixing the PANI and PAA under vigorous stirring and sonication conditions. Self‐standing films of electroactive homogeneous composites are obtained by solution casting method. A significant improvement in processibility, crystallinity, and thermal stability is observed in the composites; however, the electrical conductivity decreased remarkably as the percentage of PANI is decreased in the composites. The 60 wt % PANI‐PAA composite showed crystalline structural property with orthorhombic crystal system and cell parameters as a = 5.93Å, b = 7.57Å, and c = 10.11Å. The 60 wt % PANI‐PAA composite also showed better thermal stability and highest capacitance amongst all the composites and used as an active material for development of electrochemical capacitors (parallel plate assembly). The processible composites based electrochemical capacitors using 0.5 M NaClO₄‐Acetonitril electrolyte showed super capacitance with ease in fabrication and cost effectiveness in comparison to other similar materials based capacitors. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Electrical properties of colloidal polyaniline‐2‐naphthalene sulfonic acid/graphene nanoparticle composite films

Polyaniline (PANI) nanocomposites containing different weight percentages of graphene (GR) are chemically prepared in the presence of β‐naphthalene sulfonic acid (NSA) and characterized using attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The characterization results suggest that the composites are formed via the interconnected fibrillar structure forming the semi‐crystalline/amorphous configuration by the β‐napthalene sulfonic acid (β‐NSA). The conductivities of the composites suggest that the composites undergo by two different regions of I and II before and after 378 K. The electrical conductivity of the composites is increased by increasing temperature. The dependence of conductivity on temperature implies that the PANI‐NSA/GR composites are organic semiconductors. POLYM. COMPOS., 35:60–67, 2014. © 2013 Society of Plastics Engineers     

Polyaniline-Coated Short Nylon Fiber/Natural Rubber Conducting Composite

Natural rubber-Polyaniline (PANI)-Polyaniline coated short nylon-6 fiber (PANI-N6) composites were prepared by mechanical mixing and its cure characteristics, filler dispersion, mechanical properties, conductivity and thermal stability were evaluated. PANI was synthesized by chemical oxidative polymerization of aniline in presence of hydrochloric acid. PANI-N6 was prepared by in situ polymerization of aniline in the presence of short nylon-6 fiber. The composite showed higher tensile strength, tear strength and modulus values and lower elongation at break. The DC electrical conductivity and the thermal stability of the composites increased with PANI and PANI-N6 concentration. The highest conductivity obtained was 1.99 × 10^?6 S/cm.     

Microstructure,thermal and electrical properties of polyaniline/phenolic composite aerogel

Phenolic aerogel was first fabricated by sol–gel polymerization and freeze-drying method. Then, it was soaked into aniline solvent for 1 day. Ultimately, polyaniline/phenolic (PANI/RF) composite aerogel was obtained after the aniline molecules inside the phenolic aerogel were polymerized into polyaniline. The microstructure, thermal and electrical properties of the composites were investigated. The experimental results showed that polyaniline wires adhere to the surface of the micro holes skeleton which can be observed from the SEM images. Thus, polyaniline wires will form much smaller network inside the RF network, exhibiting an interpenetrating 3D network structure. In addition, compared with RF aerogel, PNAI/RF aerogel had maintained the thermal performance well, which showed mildly decline in heat-resistance and increase in heat conductivity, respectively. What’s more, it exhibited superior electrical performance (good specific capacitance) as compared with that of RF aerogel which is non-conducting, In general, PANI/RF aerogel with low heat conductivity (0.021 W/mK), high electrical conductivity (0.12 S/cm) and specific capacitance (280 F/g) exhibited more excellent comprehensive performance than single RF aerogel.     

MnO2/Cr2O3/PANI nanocomposites prepared by in situ oxidation polymerization method: Optical and electrical behaviors

Metal oxide–polyaniline (PANI) nanocomposite with spherical morphologies were prepared in a one-pot oxidation–reduction method via various salts as reactive oxidants. Aniline monomers polymerize as a shell on the surface of one-pot prepared metal oxides, when the aqueous solutions of aniline, a free-radical oxidant, and/or a metallic salt were exposed together. The particle size and morphology of as-prepared narrowly dispersed PANI nanocomposites were revealed by field emission scanning electron microscope images. Fourier transform infrared spectra of nanocomposites indicate that the PANI exists in the emeraldine form. The ultraviolet–visible analysis not only shows PANI is in the emeraldine form, but also indicates modified optical properties of PANI in the composite form. The hypsochromic shift of the n–π* and polaron transitions of PANI reveals the incorporation of PANI by metal oxides. The direct current (dc) electrical conductivity (σ) of as-prepared nanocomposites was measured by a four-probe method in the room temperature. Compared to PANI nanoparticles, the electrical conductivity of the composites increased with the presence of metal oxides in the nanocomposites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47219.     

Synthesis,characterization, and thermal aging behavior of HCl‐doped polyaniline/TRGO nanocomposites

In this article polyaniline (PANI) nanocomposites containing thermally reduced graphene oxide (TRGO) were synthesized and characterized before and after thermal aging. The nanocomposites were prepared through in situ oxidative polymerization of aniline in the presence of TRGO nanoplatelets. FTIR and Raman spectroscopies, XRD, FESEM, and electrical conductivity measurements were used to characterize synthesized materials. PANI/TRGO nanocomposites showed considerably higher electrical conductivity when compared to pure PANI, which was associated with the higher electrical conductivity of TRGO and increased crystallinity of PANI in the presence of TRGO. Pure PANI and PANI/TRGO nanocomposites were thermally aged at 70, 80, 90, and 100 °C. The results showed that the characteristic time of thermal aging process is higher for PANI/TRGO nanocomposites and increases with TRGO loading, which indicates better stability of conductivity during thermal aging process. On the other hand, the characteristic time of thermal aging reduced with aging temperature and a fast decrease was observed from 80 to 90 °C. Improved resistance over thermal aging can be attributed to the barrier effect of TRGO nanoplatelets to the dopant molecules, which retards conductivity degradation in the thermal aging process. Furthermore, TRGO increases PANI crystallinity and it can also prevent crystallinity reduction during thermal aging process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44635.     

Electro-optical study of thermally stable PANI/lithium doped nickel oxide composites with enhanced photoluminescence properties

PANI/Lithium doped nickel oxide nanocomposites were synthesized via in-situ chemical oxidation polymerization method. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) used to study the strucurtal confirmation of synthesized composites. FESEM images showed the fabrication of nanocomposites in porous and nanofibers form. EDS is confirming the presence of constituent elements. Thermogravimetric analysis (TGA) of fabricated materials had the excellent thermal stability extended to higher temperature after doping in host matrix. Impedance analyzer has used to examine the electrical behaviors of synthesized composites. AC conductivity of synthesized composites were enhanced as compare to pure pani. Diffuse Reflectance Spectroscopy has used to study the optical characteristics of samples. Vibrating Samples Magnetometry results of composites depicts their superparamagnetic nature. In PL investigation, photoluminescence properties of affordable electro-optical fabricated materials were found to be improved at room temperature.     

Development of whey protein isolate/polyaniline smart packaging: Morphological,structural, thermal,and electrical properties

Development of smart packaging from biodegradable polymers that allow monitoring food exposure conditions is important to reduce food and material packaging waste. The objective of this article is to evaluate the conductivity of polyaniline (PANI) in its doped form with dodecylbenzene sulfonic acid on morphological, structure, thermal, and electrical (Hall effect) properties of whey protein isolate (films. Films show immiscible with 10⁻³ S cm⁻¹ conductivity and semiconductor behavior due to a phase separation that is observed (scanning electron microscopy and thermogravimetric analysis). Fourier transform infrared and Raman spectra do not present changes in relation to control samples, suggesting no chemical interaction with polymers. This result is probably due to deprotonation of PANI. No significant differences are observed for conductivity of film made above 60 mg mL⁻¹ of PANI. Films showed semiconducting properties that allow a new application on smart packaging to help monitor electrical properties of foods in processes of degradable. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47316.     

Conductivity and anticorrosion performance of polyaniline/zinc composites: Investigation of zinc particle size and distribution effect

Polyaniline/zinc composites and nanocomposites were prepared using solution mixing method. Zinc (Zn) particles with an average particle size of 60 μm and zinc nanoparticles with an average particle size of 35 nm were used as fillers in polyaniline (PANI) matrix. Films and coatings of PANI/Zn composites and nanocomposites were prepared by the solution casting method. Electrical conductivity and anticorrosion properties of PANI/Zn composite and nanocomposite films and coatings with different zinc loadings were evaluated. According to the results, electrical conductivity and anticorrosion performances of both PANI/Zn composites and nanocomposites were increased by increasing the zinc loading. Also results showed that the PANI/Zn nanocomposite films and coatings have better electrical conductivity and corrosion protection effect on iron coupons compared to that of PANI/Zn composite.     

PANI/煤基石墨烯宏观体复合材料的制备及其电化学性能

以太西无烟煤为原料,采用催化热处理、改良Hummers氧化等方法,制备煤基氧化石墨烯（CGO）,进而以CGO和聚苯胺（PANI）为前驱体,采用水热自组装法,制备得到PANI/石墨烯宏观体复合材料（3D-PCG）。采用FT-IR、XRD、Raman、SEM和TEM等技术,研究了材料的组成、结构和形貌,考察了3D-PCG的电化学性能。结果表明,PANI以纳米棒状形态均匀镶嵌在煤基石墨烯宏观体（3D-CG）的网状结构中;当PANI与CGO质量比为1：2时,3D-PCG的电化学性能优于PANI和3D-CG,其比电容可达663 F·g^-1。     

Influence of multi-walled carbon nanotubes on the electrochemical performance of graphene nanocomposites for supercapacitor electrodes

In this work, multi-walled carbon nanotube (MWNT) bonded graphene (M-GR) composites were prepared using the chemical reduction of graphite oxide (GO) and acid treated MWNTs with different ratios. The M-GR/polyaniline (PANI) nanocomposites (M-GR/PANI) were prepared using oxidation polymerization. The effect of the M-GR ratio on the electrochemical performances of the M-GR/PANI was investigated. It was found that the substrate 2D graphene was coated with 1D MWNTs by chemical reduction and the M-GR was further coated with PANI, leading to increased electrical properties by the π–π interaction between the M-GR and PANI. In addition, the electrochemical performances, such as the current density, charge–discharge, and specific capacitance of the M-GR/PANI were higher than those of graphene/PANI and the highest specific capacitance (1118 F/g) of the composites was obtained at a scan rate of 0.1 A/g for the PANI containing a 0.5 M-GR ratio compared to 191 F/g for the graphene/PANI. The dispersion of the MWNTs onto the graphene surface and the ratio of M-GR had a pronounced effect on the electrochemical performance of the PANI-based composites, which was attributed to the highly conductive pathway created by the M-GR incorporated in the PANI-based composites and the synergistic effect between M-GR and PANI.     

Ferromagnetic polyaniline/TiO2 nanocomposites

Novel ferromagnetic semiconducting polyaniline PANI/TiO₂ nanocomposites were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous medium, in the presence of colloidal TiO₂ nanoparticles (d ∼ 4.5 nm), without added acid. The morphological, magnetic, structural, and optical properties of the PANI/TiO₂ nanocomposites prepared at initial aniline/TiO₂ mole ratios 80, 40, and 20 were studied by scanning electron microscopy, superconducting quantum interference device, X‐ray powder diffraction, FTIR, Raman, and UV‐Vis spectroscopies. The emeraldine salt form of linear PANI chains as well as the presence of phenazine units, branched PANI chains, and anatase crystalline structure of TiO₂ in PANI/TiO₂ nanocomposites was confirmed by FTIR and Raman spectroscopies. The electrical conductivity of synthesized composites was ∼10⁻³ S cm⁻¹. The room temperature ferromagnetic response with coercive field of H_c ∼ 300 Oe and the remanent magnetization of M_r ∼ 4.35 × 10⁻⁴ emu/g was detected in all investigated PANI/TiO₂ nanocomposites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

PANI–LDPE composites: Effect of blending conditions

A composite based on polyaniline (PANI) and low density polyethylene (LDPE) with electrical conductivity was developed. Polyaniline was polymerized by chemical oxidation and doped with dodecyl‐benzene‐sulfonic acid (DBSA). PANI–LDPE composites were prepared via melt blending and the films were obtained by compression molding. The influence of three variables of the blending (temperature, [PANI], rotor speed) on conductivity, microstructure and mechanical properties of the composites was studied by means of statistical tools and a 2³ experimental design. The results show that the PANI concentration is the most influential variable, which mainly affects the conductivity and the elongation at break of the composites. These changes are related to the microstructure of the composites. Statistically, the other variables don't show significant influence on conductivity and mechanical properties in the studied range. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.     

Optical,electrical, and electrochemical properties of graphene based water soluble polyaniline composites

Polyaniline (PANI) is one of the most common polymers known for its conducting properties. However, poor water solubility limits its applications. In this work, PANI has been functionalized with sulfonic acid groups to produce sulfonated PANI (SPANI) offering excellent solubility in water. To compensate for the decrease of electrical conductivity due to functionalization, SPANI was combined with reduced graphene oxide (RGO) to form SPANI/RGO composites with interesting optical, thermal, and electrical properties. The composites have been characterized using X‐ray diffraction (XRD), field emission scanning electron microscopy, UV–vis absorption spectroscopy, Raman spectroscopy, Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, thermogravimetric analysis, cyclic voltammetry, and four probe electrical conductivity measurement. The SPANI/RGO composites show increased thermal stability, reduced optical band gap and improved electrochemical properties compared with the pure polymer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42766.