Multifunctional polyaniline–tin oxide (PANI–SnO2) nanocomposite: Synthesis,electrochemical, and field emission investigations

Synthesis of PANI–SnO₂ nanocomposite has been performed using a simple two step chemical oxidative polymerization route. The structural, morphological and chemical properties of the as‐synthesized PANI–SnO₂ nanocomposite have been revealed by various characterization techniques such as SEM, TEM, XRD, FTIR, and XPS. Interestingly the as‐synthesized PANI–SnO₂ nanocomposite exhibits supercapacitance value of 721 F g^?1 with energy density 64 Wh kg^?1, which is noticed to be higher than that of pristine SnO₂ and PANI nanostructures. Furthermore, the galvanostatic charge–discharge characteristics revealed pseudocapacitive nature of the PANI–SnO₂ nanocomposite. The estimated values of charge transfer resistance and series resistance estimated from the Nyquist plot are found to be lower. Along with the supercapacitive nature, PANI–SnO₂ nanocomposite showed promising field emission behavior. The threshold field, required to draw emission current density of 1 μA/cm², is observed to be 0.90 V/μm and emission current density of 1.2 mA/cm² has been drawn at applied field of ～2.6 V/μm. The emission current stability investigated at preset values of 0.02 and 0.1 mA/cm² is observed to be fairly stable over duration of more than 3 h. The enhanced supercapacitance values, as well as, the promising field emission characteristics are attributed to the synergic effect of SnO₂ nanoparticles and PANI nanotubes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41401.     

Chemical synthesis,characterization, and direct‐current conductivity studies of polypyrrole/γ‐Fe2O3 composites

The in situ polymerization of pyrrole was carried out in the presence of γ‐Fe₂O₃ to synthesize polypyrrole/γ‐Fe₂O₃ composites by a chemical oxidation method. The polypyrrole/γ‐Fe₂O₃ composites were synthesized with various compositions, including 10, 20, 30, 40, and 50 wt % γ‐Fe₂O₃ in pyrrole. The polypyrrole/γ‐Fe₂O₃ composites were characterized with X‐ray diffractometry and infrared spectroscopy. The surface morphology of these composites was studied with scanning electron microscopy. The direct‐current conductivity was studied from 40 to 200°C. The dimensions of the γ‐Fe₂O₃ particles in the matrix had a greater influence on the conductivity values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2797–2801, 2007     

Preparation and electrochemical properties of polyaniline/reduced graphene oxide composites

Polyaniline (PANI)/reduced graphene oxide (rGO) composites were synthesized by in situ oxidative polymerization of aniline on reduced graphene sheets. Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscopy were used to characterize the composites. The results indicated PANI/rGO composites were produced and contained covalent bonds between the functional groups of PANI and rGO. A uniform coating of PANI on the rGO sheets had a synergistic effect on the properties of the composites. The electrochemical properties of the PANI/rGO composites produced using different feed ratios of aniline to rGO were studied. The results showed that the composites exhibited a maximum specific capacitance of 797.5 F/g at 0.5 A/g and minimum charge transfer resistance of 0.98 Ω when the feed ratio of aniline to rGO was 2:1. These values were superior to those of pure PANI and rGO. The composites also displayed excellent cycling stability, with specific capacitance retention of 92.43% after 1000 cycles. These stable structural composites show promise for the development of new supercapacitor applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46103.     

Rheological behavior ‐ Electrical and thermal properties of polypyrrole/graphene oxide nanocomposites

Polypyrrole/graphene oxide (Ppy/GO) nanocomposites were synthesized via in situ polymerization of pyrrole in the presence of GO at various proportions (1–5%). They were characterized to determine their electrical, thermal, and rheological properties by various techniques. The aim of this study was to determine the rheological behavior of Ppy/GO nanocomposite at different mass ratios (100 : 1, 100 : 2, 100 : 3, 100 : 4, and 100 : 5%) and temperature (25–180°C) using a rotational mode in cone‐plate method. The shear stress (τ Pa) and viscosity (η Pa s) values of the nanocomposites increased with the increase in GO mass ratio added to Ppy, which was accompanied by an increased flexibility of the nanocomposites due to the higher aspect ratio of the GO sheet. Hence, it is suggested that the GO sheets are effective for the reinforcement of Ppy thereby significantly improvising its thermal stability, electrical conductivity, and rheological properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40642.     

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     

Nanostructured star‐shaped polythiophene with tannic acid core: Synthesis,characterization, and its physicochemical properties

For the first time, synthesis and characterization of a nanostructured star‐shaped polythiophene (PTh) with tannic acid core by both chemical and electrochemical oxidation polymerization methods through a “core‐first” method is reported. The chemical structures of all samples as representatives were characterized by means of Fourier transform infrared (FTIR), and ¹H nuclear magnetic resonance (NMR) spectroscopies. The electroactivity behaviors of the synthesized samples were verified under cyclic voltammetric conditions, and their conductivities were determined using the four‐probe technique. The synthesized star‐shaped PTh showed higher electrical conductivity and electroactivity than those of the PTh in both chemical and electrochemical polymerized samples, due to its large surface area, spherical, and three‐dimensional structure. Moreover, the thermal behaviors, optical properties, and morphologies of the synthesized samples were investigated by means of thermogravimetric analysis (TGA), ultraviolet–visible (UV–Vis) spectroscopy, and field emission scanning electron microscopy (FE‐SEM), respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43513.     

In situ synthesis of cabbage like polyaniline@hydroquinone nanocomposites and electrochemical capacitance investigations

A Cabbage like polyaniline@hydroquinone composite microsphere was synthesized using in situ polymerization and the electrochemical performance was investigated. The core template, p‐benzoquinone, is demonstrated working as an oxidizing agent for the in situ polymerization of PANI, and to be reduced to 1, 4‐hydroquinone after reaction. The morphology and microstructure of samples were examined by field emission scanning electron microscopy, transmission electron microscope, X‐ray photoelectron spectrometer, thermo gravimetric, and Fourier transform infrared spectra. The cyclic voltammetry, impedance and galvanostatic charge/discharge analysis demonstrates that PANI contributes electronic conductive channels for hydroquinone, and hydroquinone works as a pseudocapacitance component. The prepared PANI@hydroquinone nanocomposite exhibits brilliant electrochemical properties of a specific capacitance of 126.0 F g^?1 at a scan rate of 5 mV s^?1 and enhanced stability of about 85.1% of initial capacitance retained after 500 cycles scanning at a current density of 1 A g^?1. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42290.     

Facile synthesis of graphene/polypyrrole 3D composite for a high‐sensitivity non‐enzymatic dopamine detection

One kind of nanocomposite consisting of graphene and polypyrrole was synthesized via a facile and mild way with the assistant of microwave irradiation. The synthesis route was embedding the polypyrrole into the graphene flakes to form a 3D structure, to achieve larger active surface and higher electro‐catalysis property. Structures and components of the composite were measured by X‐ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. A stronger electrochemical response of electrode with modified resultant was observed in the electrochemical test. Dopamine sensor based on the composite showed a sensitivity of 363 μA mM ^?1 cm^?2, a linear range of 1 × 10^?4 M to 1 × 10^?3 M , and a detection limit of 2.3 × 10^?6 M (S/N = 3). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44840.     

Structure and morphology of nanoporous zno and dark current‐Voltage characteristics of the glass/(TCO)/zno/poly[2,7‐(9,9‐dioctylfluorene)‐alt‐(5,5'‐bithiophene)/ag structure

The hybrid organic‐inorganic structure based on glass/(TCO)/nanoporous ZnO/poly[2,7‐(9,9‐dioctylfluorene)‐alt‐(5,5′‐bithiophene)]/Ag that was prepared by physical deposition has been investigated. The structure of the nanostructured ZnO obtained by magnetron sputtering was confirmed by X‐ray diffractometry (XRD) and energy dispersive X‐ray spectroscopy (EDX). Scanning electron microscopy (SEM) analysis proved the existence of short and interconnected zinc oxide (ZnO) fibers, which form a continuous porous network with pores having an average diameter of 100 nm. Current‐voltage (I‐V) curves of the glass/TCO/ZnO/PF‐BT/Ag hybrid structure are similar to those of typical p‐n junctions and stable until 90°C temperature. According to the I‐V characteristics, the dominant mechanism of current flow is based on the generation‐recombination of carriers in the depletion region at low direct biases and also on the injection of carriers at high biases. The reverse branch of the I‐V characteristic, calculated in log‐log scale, shows one segment with a power coefficient of 3/2 at room temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42415.     

Preparation and properties of dopamine reduced graphene oxide and its composites of epoxy

To improve the thermal and mechanical properties and further to expand its applications of epoxy in electronic packaging, reduced graphene oxide/epoxy composites have been successfully prepared, in which dopamine (DA) was used as reducing agent and modifier for graphene oxide (GO) to avoid the environmentally harmful reducing agents and address the problem of aggregation of graphene in composites. Further studies revealed that DA could effectively eliminate the labile oxygen functionality of GO and generate polydopamine functionalized graphene oxide (PDA‐GO) because DA would be oxidated and undergo the rearrangement and intermolecular cross‐linking reaction to produce polydopamine (PDA), which would improve the interfacial adhesion between GO and epoxy, and further be beneficial for the homogenous dispersion of GO in epoxy matrix. The effect of PDA‐GO on the thermal and mechanical properties of PDA‐GO/epoxy composites was also investigated, and the incorporation of PDA‐GO could increase the thermal conductivity, storage modulus, glass transition (T_g), and dielectric constant of epoxy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39754.     

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.     

Electrochemical inspection of polypyrrole/chitosan/zinc oxide hybrid composites

Polymer nanocomposite composed of polypyrrole, chitosan, and zinc oxide nanoparticles has been synthesized and it has been evaluated for various electrochemical aspects of the current electrochemical industry. The polypyrrole (PPy) was synthesized by the chemical oxidative polymerization reaction by employing ammonium persulfate as oxidizing agent. Composites of polypyrrole/chitosan (PPy/Chy) and polypyrrole/chitosan/ZnO (PCZ) composites were synthesized by the solution blending method. Detailed structural, morphological, thermal characterization of PPy, PPy/Chy, and PCZ were performed to characterize the specific features of the systems. The composites exhibit better thermal stability and high surface area and the addition of ZnO nanoparticle increase the crystallinity of the composite. Electrochemical characterization of the ITO electrodes modified with PPy, PPy/Chy, and PCZ were performed using cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry techniques. The present study highlights the role of a bio-compatible material with high surface area and conductive constituent for designing of various high performing electronic noninvasive sensors, biosensors, and so forth.     

Controlled electrochemical synthesis of conductive nanopolypyrrole and its application in the design of a solid‐state ion sensor

A polypyrrole (PPy) conductive polymer was electrochemically synthesized from pyrrole–cupric chloride (CuCl₂)–H₂O (system A) and pyrrole–CuCl₂–sodium dodecyl sulfate–H₂O (system B). Their morphologies and growth behavior were studied, and their aggregates were characterized by powder X‐ray diffraction, scanning electron microscopy, transmission electron spectroscopy, thermogravimetry, and Fourier transform infrared studies. The powder X‐ray diffraction pattern showed only one peak characteristic of PPy. In system B, the dimensions of the fractal patterns were calculated and found to be very close to the theoretical value of diffusion‐limited aggregation. Various morphological transitions were observed at different field intensities and CuCl₂ concentrations. Transmission electron spectroscopy studies revealed the formation of nanosized spherical particles 5–10 nm in size. For system B, a potassium‐ion‐selective electrode was constructed on the basis of a dibenzo‐18‐crown‐6 impregnated poly(vinyl chloride) matrix membrane over a synthesized polymer‐modified electrode. The electrode showed Nernstian behavior with a slope of 57 mV; this revealed the potential application of the as‐synthesized material in the design of a solid‐state ion‐selective electrode. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42729.     

One‐pot synthesis of monodispersed phosphazene‐containing microspheres with active amino groups

An amine‐terminated nucleophile Hexakis (4‐aminophenoxy) cyclotriphosphazene (HACP) was synthesized. Its chemical structure was identified by ¹H NMR and ³¹P NMR. Novel monodispersed phosphazene‐containing microspheres with active amino groups on the surface have been successfully prepared through a one‐pot precipitation polymerization of hexachlorocyclotriphosphazene with HACP. Just by single step, the microspheres were synthesized without stirring, surfactant and ultrasonic irradiation. The diameter of the obtained microspheres ranged from 0.1 to 0.5 μm with the rough surface. And, the onset of the thermal‐degradation temperature was 460°C, which is attributed to the highly cross‐linked structure and the introduced of the cyclotriphosphazene rings. Moreover, the products at variable stages of polymerization were measured by TEM. The formation mechanism was proposed which is corresponding with an oligomeric species absorbing mechanism. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43336.     

Electrochemical behavior of a Nafion‐membrane‐based solid‐state supercapacitor with a graphene oxide—multiwalled carbon nanotube—polypyrrole nanocomposite

In this study, we sprayed a graphene oxide–multiwalled carbon nanotube (GM) suspension in isopropyl alcohol–water onto a Nafion membrane. The electrodeposition of polypyrrole (PPy) was carried out on Nafion to complete the fabrication of a solid‐state symmetric supercapacitor. Nafion 117 membranes are used as electrolyte separators in the preparation of supercapacitors. The characterization of the symmetric supercapacitor was done by X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the symmetric solid‐state supercapacitor were investigated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques in 1M lithium chloride. A specific capacitance of 90.4 mF/cm² (258.3 F/g¹) was obtained for the supercapacitor at a scan rate of 10 mV s^?1. Maximum energy and power densities of 10 W h/kg and 6031 W/kg were obtained for the fabricated supercapacitor. In such a symmetric configuration, the highly interconnection networks of GM–PPy provided good structure for the supercapacitor electrode, and the good interaction between PPy and GM provided fast electron‐ and charge‐transportation paths so that a high capacitance was achieved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44926.     

Polyaniline self‐assembled with DTPA: Facilely tuned morphology and properties

The effects of pH profile and “soft template” during aniline chemical oxidative polymerization (COP) were investigated and evaluated simultaneously with diethylene triamine pentaacetic acid (DTPA) as a structural directing agent. Formation of PANI nanotubes and nanoparticles, smooth microspheres, and urchin‐like microspheres were illustrated by evaluating the pH profile during aniline COP while considering the “soft template” effects of DTPA. PANI nanosheets with two semicurled edges were found in the system producing nanotubes, which provides an evidence for the “curling mechanism” of PANI nanotube formation. With different pH profiles, chemical structures and aggregation structures of the as‐synthesized PANI micro/nanostructures are similar, whereas their conductivity, wettability, Cr (VI) adsorption, and electrochemical behaviors are distinct. The present study indicates that if properly conducted, pH profile adjustment is more effective than “soft template” to control the morphology and to optimize the performance of PANI micro/nanostructures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42403.     

Formulation of chemically reduced graphene oxide assembly with poly(4‐vinyl pyridine) through noncovalent interaction

Soluble chemically reduced graphene oxide (RGO)/poly(4‐vinyl pyridine) (P4VP) assembly was attempted by totally noncovalent approach. Chemical reduction of P4VP/GO mixture by hydrazine produced soluble RGO/P4VP assembly with long term stability. Prepared RGO/P4VP assembly showed pH‐dependent variation of optical transmittance. Transmittance of RGO/P4VP assembly solution at pH 2.0 dramatically increased more than 200% of transmittance of assembly at pH 6. This optical transmittance change was fully reversible. The detailed morphological features of assemble was evaluated by dynamic light scattering (DLS) and atomic force microscopy (AFM). It is estimated that RGO/P4VP assemblies were well separated each other at pH 6, enabling much higher optical absorption of RGO plates. At pH 2, protonation of pyridine ring occurs and this might hamper effective noncovalent interaction between RGO plate and protonated P4VP chains, forming bigger aggregates having less chance for optical absorption. This pH‐dependent optical modulation of RGO/P4VP assembly can be useful for the designing of pH‐sensor, removable nanocatalyst, and targeted drug delivery, etc. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2538–2543, 2013     

Electrocatalysis and detection of nitrite on a polyaniline‐Cu nanocomposite‐modified glassy carbon electrode

A polyaniline (PANI)‐Cu nanocomposite‐modified electrode was fabricated by the electrochemical polymerization of aniline and the electrodeposition of copper under constant potentials on a glassy carbon electrode (GCE), respectively. Scanning electron microscope result shows that the PANI‐Cu composite on the surface of the GCE displays the nanofibers having an average diameter of about 80 nm with lengths varying from 1.1 to 1.2 μm. The electrode exhibits enhanced electrocatalytic behavior to the reduction of nitrite compared to the PANI‐modified GCE. The effects of applied potential, pH value of the detection solution, electropolymerization charge, temperature, and nitrite concentration on the current response of the composite‐modified GCE were investigated and discussed. Under optimal conditions, the PANI‐Cu composite‐modified GCE can be used to determine nitrite concentration in a wide linear range (n = 18) of 0.049 and 70.0 μM and a limit of detection of 0.025 μM. The sensitivity of the electrode was 0.312 μA μM^?1 cm^?2. The PANI‐Cu composite‐modified GCE had the good storage stability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Few‐layer‐graphene/polycarbonate nanocomposites as dielectric and conducting material

An attempt is taken to develop a flexible and light weight polycarbonate‐based nanocomposite system which could be successfully used as a dielectric material below percolation and as conducting material beyond percolation. The nanocomposite system has been prepared by solution mixing method in which few layer graphene was incorporated as conductive filler. X‐ray diffractometry, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy techniques were employed for characterization studies. The dielectric constant and conductivity were evaluated using precision impedance analyzer. Percolation threshold has been observed to occur at 3.5 wt % of few layer graphene. Dielectric constant of the nanocomposite system, in the smearing region, has been found to increase from ～3.3 (without filler) to ～70 (at 5 wt % FLG) with a dissipation factor of 0.07. The conductivity of the system was increased from 10^?9 S/cm without FLG to 10^?2 S/cm with 7 wt % of few layer graphene. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42443.     

A novel method for synthesis of water‐soluble polypyrrole with horseradish peroxidase enzyme

A novel water‐soluble, conducting polypyrrole was synthesized by horseradish peroxidase (HRP), in the presence of sulfonated polystyrene, as a polyanionic template. The HRP is an effective catalyst for the oxidative polymerization of pyrrole in the presence of hydrogen peroxide at room temperature. The reaction is sensitive to solution pH and it is performed in pH 2 aqueous solutions. Polymerization of pyrrole by this biological route produced a conducting water‐soluble polypyrrole for the first time. The reaction is benign and in one pot, and the product requires minimal purification. The reversible redox activity of the polypyrrole displays a hystersis loop with pH changes. FT‐IR, UV‐vis absorption spectroscopy, and cyclic voltammetry are used in the characterization of the synthesized polypyrrole. These studies confirm the electroactive and conducting form of polypyrrole, similar to that which has been traditionally synthesized, chemically and electrochemically. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 254–258, 2004