Comparison of the corrosion protection of mild steel by polypyrrole–phosphate and polypyrrole–tungstenate coatings

The electrodeposition of polypyrrole–phosphate (PPy–P) and polypyrrole–tungstenate (PPy–W) on mild steel (MS) were achieved in an oxalic acid medium with cyclic voltammetry techniques. Adherent and homogeneous PPy–P and PPy–W films were obtained. The corrosion behavior of mild steel with phosphate (PPy–P) and tungstenate (PPy–W) composite coatings in 3.5% NaCl solutions were investigated through a potentiodynamic polarization technique, open‐circuit potential–time curves, and electrochemical impedance spectroscopy (EIS). On the basis of a physical model for corrosion of mild steel composites, Zview (II) software was applied to the EIS to estimate the parameters of the proposed equivalent circuit. It was found that the PPy–W coatings could provide much better protection than the PPy–P and polypyrrole coatings. The effects of the phosphate and tungstenate process parameters on the morphology and structure of the passive films were investigated by scanning electron microscopy and electron dispersion X‐ray analyses. The results reveal that the PPy–P and PPy–W coated electrodes offered a noticeable enhancement in protection against corrosion processes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Laccase‐catalyzed synthesis of conducting polyaniline‐lignosulfonate composite

Enzymatic polymerization of aniline was first performed in lignosulfonate (LGS) template system. High‐redox‐potential catalyst laccase, isolated from Aspergillus, was used as a biocatalyst in the synthesis of conducting polyaniline/lignosulfonate (PANI‐ES‐LGS) complex using atmospheric oxygen as the oxidizing agent. The linear templates (LGS), also serving as the dopants, could facilitate the directional alignment of the monomer and improve the solubility of the conducting polymer. The process of the polymerization was monitored using UV‐Vis spectroscopy, by which the conditions for laccase‐catalyzed synthesis of PANI‐ES‐LGS complex were also optimized. The structure characterizations and solubility of the complex were carried out using corresponding characterization techniques respectively. The PANI‐ES‐LGS suspensions obtained was used as coating for cotton with a conventional padder to explore the applications of the complex. The variable optoelectronic properties of the coated cotton were confirmed by cyclic voltammetry and color strength test. The molecular weight changes of LGS treated by laccase were also studied to discuss the mechanism of laccase catalyzed aniline polymerization in LGS template system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42941.     

Electrical properties of poly(phenylene sulfide)/multiwalled carbon nanotube composites prepared by simple mixing and compression

Poly(phenylene sulfide) (PPS)/multiwalled carbon nanotubes (MWNTs) conductive composites were prepared through the simple mixing of PPS granules with MWNT powder and subsequent compression. The electrical properties as a function of MWNT loading clearly showed a low percolation threshold of about 0.22 vol % and a high critical exponent value of 3.55 for composites prepared by this method. A comparison study with composites prepared via melt mixing was also carried out, where a random dispersion of MWNTs was achieved. There existed a striplike morphology of MWNTs in the PPS matrix and MWNTs were selectively located in strips caused by compression. The effects of temperature and pressure on the conductivity of the PPS/MWNT composites as prepared via simple mixing and compression are discussed. In addition, the conductivity also showed a dependence on the flow direction of the compression, with higher conductivity in the direction parallel to the flow direction than in the direction perpendicular to the flow direction. So the relationship of the processing and morphological properties was investigated in detail. The possible conductive mechanisms of conventional melt blending and preparation via sample mixing and compression are also discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of composites of polyaniline nanorods and multiwalled carbon nanotubes coated with polyaniline

Composites of polyaniline (PANI) nanorods and multiwalled carbon nanotubes (MWNTs) coated with PANI were prepared by in situ polymerization with perchloric acid as a dopant. Transmission electron microscopy images showed that the coexisting composites of PANI nanorods and MWNTs coated with PANI were formed at low MWNT contents. The interaction between MWNTs and PANI was proved by Fourier transform infrared and ultraviolet–visible spectra. The electrical conductivity of a dedoped PANI/MWNT composite with a 16.3 wt % concentration of MWNTs reached 3.0 × 10^?3 S/cm, which was 6 orders of magnitude higher than that of dedoped PANInanorods. The results also showed that coexisting composites of PANI nanorods and MWNTs coated with PANI had high electrochemical activity and good cyclic stability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Laccase‐catalyzed polymerization drying of Chinese lacquer sap with TiO2 nanoparticles

Nano‐TiO₂/lacquer hybrid coatings are prepared by the blend of nano‐TiO₂ and lacquer sap. Nano‐TiO₂ particles are involved in the laccase‐catalyzed polymerization process of urushiol, which improves the properties of lacquer film. With increasing nano‐TiO₂ from 0 to 5 wt %, the drying time of lacquer film to reach hardened dryness decreases from >12 h to 8 h 30 min under 30 °C and 80% relative humidity. Gel permeation chromatography analysis shows that the addition of nano‐TiO₂ accelerates the polymerization of urushiol. It is also related to the formation of Ti? O? C bonds due to the reaction between nano‐TiO₂ and the radicals produced by laccase‐catalyzed oxidation. The pencil hardness, flexibility, and adhesion of hybrid lacquer film can be improved and reach 4H, 1 mm, and grade 2, respectively. Its inhibition rate against Escherichia coli and Staphylococcus aureus increases from 22.6% and ?21.4% to 49.2% and 67.8%, respectively. Furthermore, nano‐TiO₂ hybrid lacquer films also possess higher thermo‐stability than the raw lacquer film. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45865.     

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.     

Enhancing the performance of polypyrrole composites as electrode materials for supercapacitors by carbon nanotubes additives

In the framework of this study, a facile method to obtain polypyrrole (PPy)/carbon nanotubes composites is presented. Chemical polymerization of PPy directly on the carbon nanotubes allows to obtain a homogenous distribution of the polymer. A low amount of carbon additive, varying from 1.5 to 5.5 wt %, is applied in order to prevent the decrease of capacitance value due to the presence of a low-capacitance component and, at the same time, to protect the electrode material from mechanical changes during cycling electrical measurements. The electrochemical properties, such as capacitance, its retention at different current loads, cycling stability, or self-discharge, are discussed. Improvement of electrochemical performances of the synthesized materials is observed mostly during cyclic stability measurements and at high current regimes. The obtained results confirm that the addition of only 3% of carbon nanotubes provides the best electrochemical performances as electrode materials for supercapacitor application. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48867.     

Effect of orientation and content of carbon based fillers on thermal conductivity of ethylene‐propylene‐diene/filler composites

In this study, synthetic graphite, carbon fiber, and carbon nanotube were used as thermal conductive fillers and ethylene‐propylene‐diene (EPDM) as matrix. Oriented EPDM/filler composites were prepared with two‐roll mill, and the effects of orientation and content of carbon based fillers on thermal conductivity and tensile strength of the composites were investigated. Parallel thermal conductivity of the oriented composites is significantly higher than normal thermal conductivity of the oriented composites. Especially, at 31.6% graphite content, parallel thermal conductivity of oriented composites is 7.14 W/mK. Very high thermal conductivity was achieved for oriented EPDM/graphite composites. Orientation of the fillers using two‐roll mill significantly improves the thermal conductivity in the orientation direction. For all the EPDM/filler composites, tensile strength of orientation direction is higher than that of normal direction. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41000.     

Effect of processing parameters on the surface resistivity of ethylene propylene diene terpolymer/multiwalled carbon nanotube nanocomposites

In this study, ethylene propylene diene terpolymer (EPDM) is melt‐mixed with multiwalled carbon nanotube (MWCNT). To realize full‐scale application of MWCNT to the rubber industries, the effect of melt‐processing parameters on the surface resistivity in the rubber/MWCNT nanocomposites should be well understood. The effect of rotor speed, mixing temperature, and annealing time on the surface resistivity of the EPDM/MWCNT nanocomposites has been investigated. The surface resistivity of EPDM/MWCNT nanocomposites with 3 phr MWCNT increases with increasing the rotor speed and decreasing the mixing temperature. Tensile strength and tensile modulus of EPDM/MWCNT (3 phr) nanocomposites are higher than those of EPDM, respectively. For the nanocomposite with 3 phr MWCNT loadings, surface resistivity increases as the annealing time at room temperature increases. This is the first report that surface resistivity of rubber/MWCNT nanocomposites increases significantly on annealing at room temperature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40129.     

Enhancement in electrical conductive property of polypyrrole‐coated cotton fabrics using cationic surfactant

Recently, great efforts have been made to gain highly conductive fabrics for smart textiles and flexible electromagnetic shielding materials. Different from the conventional chemical synthesis method, fibrillar polypyrrole was synthesized on the cotton fabrics via a simple chemical polymerization process with micelles of cationic surfactant (cetyltrimethylammonium bromide, CTAB) as soft template. The modified cotton fabric exhibited excellent electrical conductivity and electromagnetic interference shielding effectiveness due to the formation of fibrillar polypyrrole on the fiber surface. Electrical conductivity of fabric surface were studied by four‐probe resistivity system. The highly conductive fabric with surface conductivity of 5.8 S cm^?1 could be obtained by changing cationic surfactant concentration. The electromagnetic interference shielding effectiveness (EMI SE) of the modified fabrics was evaluated by the vector network analyzer instrument. Compared with the sample without using surfactant, the EMI SE value of PPy‐coated cotton fabrics increased by 28% after using 0.03 M CTAB as soft template. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43601.     

Conducting polymer composites of multiwalled carbon nanotube filled doped polyaniline

A multiwalled carbon nanotube (c‐MWNT)/polyaniline (PANI) composite was synthesized by an in situ chemical oxidative polymerization process. With the carbon nanotube loading increased from 0 to 30 wt %, the conductivity also increased and became weakly temperature‐dependent. Fourier transform infrared spectroscopy studies showed that the synthesis by an in situ process led to effective site‐selective interactions between the quinoid ring of the PANI and the multiwalled nanotubes, facilitating charge‐transfer processes between the two components. The morphological analysis indicated that the c‐MWNTs were well dispersed and isolated, and the tubes became crowded proportionally to the weight percentage of c‐MWNTs used in the composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and enhanced electrochemical properties of Ag/polypyrrole composites electrode materials

Ag/polypyrrole (PPy) composites were synthesized with different dispersants via interface polymerization method. The morphology of the composites was investigated by scanning electron microscopy and transmission electron microscopy, and the results showed that the dispersant had strong effect on the morphology of the obtained composites. The structure of the products was characterized by Fourier transform infrared spectroscopy, and X‐ray diffraction. The specific capacitance and impedence of Ag/PPy composites electrode was evaluated through charge/discharge measurements and electrochemical impedance spectroscopy, respectively. Electrochemical performances indicated that Ag/PPy composite electrode used polyvinyl alcohol as dispersant exhibited the highest specific capacitance of 635.5 F/g at a current density of 2.45 mA/g, which provided potential application as supercapacitor materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Composite sodium p‐toluene sulfonate–polypyrrole–iron anode for a lithium‐ion battery

In this study, p‐toluene sulfonate (TsONa) doped polypyrrole (PPy) was synthesized for an anode in a lithium‐ion battery via a one‐step facile electropolymerization on Fe foil. The obtained TsONa–PPy–Fe composite electrode was investigated with scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, and galvanostatic charge–discharge profiling. As expected, many irregular microspherical particles of TsONa‐doped PPy formed and combined tightly with the surface of Fe foil. Furthermore, the obtained TsONa–PPy–Fe anode also delivered satisfactory electrochemical performances. For example, the reversible capacity was still about 105–115 mAh/g, even after at least 50 cycles. The high lithium storage activity of PPy and the high conductivity of the TsONa‐doped PPy jointly contributed into the satisfactory electrochemical performances. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44935.     

Capacitance properties of graphite oxide/poly(3,4‐ethylene dioxythiophene) composites

Poly(3,4‐ethylene dioxythiophene) (PEDOT) and graphite oxide (GO)/PEDOT composites (GPTs) doped with poly(sodium styrene sulfate) (PSS) were synthesized by in situ polymerization in aqueous media. The electrochemical capacitance performances of GO, PEDOT–PSS, and GPTs as electrode materials were investigated. The GPTs had a higher specific capacitance of 108 F/g than either composite constituent (11 F/g for GO and 87 F/g for PEDOT–PSS); this was attributable to its high electrical conductivity and the layer‐within/on‐layer composite structure. Such an increase demonstrated that the synergistic combination of GO and PEDOT–PSS had advantages over the sum of the individual components. On the basis of cycle‐life tests, the capacitance retention of about 78% for the GPTs compared with that of 66% for PEDOT–PSS after 1200 cycles suggested a high cycle stability of the GPTs and its potential as an electrode material for supercapacitor applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A highly selective electrochemical sensor for l‐tryptophan based on a screen‐printed carbon electrode modified with poly‐p‐phenylenediamine and CdS quantum dots

A new highly selective electrochemical sensor for the determination of l ‐tryptophan was proposed by modifying the surface of screen‐printed carbon electrodes (SPCEs). The surface of SPCE was firstly modified by electropolymerization of p‐phenylenediamine (PPD). The polymer film was then covalently linked with cysteamine capped cadmium sulfide quantum dots (Cys‐CdS QDs) by using glutaraldehyde (GA) as a cross‐linker resulted in an organic–inorganic hybrid composite film (QDs/GA/PPD/SPCE). The modified electrode was applied as a working electrode for detecting various amino acids. It was found that the modified electrode gave an electrochemical response selectively to l ‐tryptophan over other amino acids. The experimental parameters, including pH of solution, buffer types, electropolymerization cycles, scan rate, and accumulation time, were studied and optimized. The proposed sensor can be used to detect l ‐tryptophan with a low detection limit of 14.74 µmol L^?1 with good precision and the relative standard deviation less than 3.7%. The modified electrode was used to detect l ‐tryptophan in beverage samples and gave satisfactory recoveries from 91.9 to 104.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40356.     

Disposable potentiometric citrate sensor based on polypyrrole‐doped films for indirect determination of sildenafil in pharmaceuticals formulations

A new sensitive and selective disposable potentiometric sensor based on polypyrrole (PPy) films for determination of sildenafil citrate (SC) was proposed. The pyrrole polymerization was performed in presence of citrate ions under galvanostatic conditions which resulted in a membrane of PPy doped with citrate anion at graphite pencil electrode surface. Experimental conditions (e.g., pH and conditioning time) and instrumental parameters (e.g., current density and electrical charge) were evaluated in order to reach the best potentiometric response for the proposed sensor. Under optimized conditions, the device presented a linear dynamic range (LDR) for citrate ions concentrations varying from 0.034 to 1.7 mmol L^?1 with a Nernstian slope of 57.2 mV dec^?1 and a limit of detection (LOD) of 30 µmol L^?1. The developed potentiometric sensor was applied for sildenafil citrate (SC) determination (pharmaceutical formulations) and results compared with an official spectrophotometric method indicating a good agreement for a confidence level of 95%. Effect of concomitants species on the potentiometric response of the proposed device and morphologic characterization using microscopy of atomic force (AFM) were realized. The surface roughness of PPy films (synthesized in citrate solution and chloride) showed poorly affected by changing the doping anion, probably because the polypyrrole nodules grow three‐dimensionally simultaneously. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43762.     

Conductive fibers based on poly(ethylene terephthalate)–polyaniline composites manufactured by electrochemical polymerization

A novel method of manufacturing composite conductive fibers was developed through electrochemical polymerization with an apparatus consisting of insulating fibers, cotton fabrics as electrolytic solution holders, an electrolytic solution, and planer electrodes. By this method, poly(ethylene terephthalate) (PET) fibers coated with polyaniline (PAN) were prepared readily and yielded PET–PAN composite conductive fibers (PPCFs). The content of PAN in PPCFs increased with an increase in both the aniline concentration in the electrolytic solution and the polymerization voltage, although it did not depend on the load applied to the electrodes. Observations of the PPCF surface by scanning electron microscopy confirmed that the formation processes of PPCFs could be divided into three steps: (1) fine (nanometer‐size) granular PAN was generated from the anode and adsorbed onto the PET fiber surface, (2) the size of the granular PAN increased up to about 90 nm in a short time, and (3) the granular PAN was linked together to form networks. The conductivity of PPCFs increased with an increasing content of PAN networks. The surface resistance of the PPCF fabric was about 3 × 10⁵ Ω/□ at a PAN content of approximately 2 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1073–1078, 2003     

Polypyrrole–multiwalled carbon nanotubes composites as immobilizing matrices of ascorbate oxidase for the facile fabrication of an amperometric vitamin C biosensor

An amperometric vitamin C biosensor was facilely fabricated by the immobilization of ascorbate oxidase (AO) on polypyrrole (PPy)–multiwalled carbon nanotubes (MWCNTs) composites with a one‐step electrodeposition technique in a 0.05M phosphate buffer solution (pH 6.5). The cyclic voltammetry, IR spectral analysis, electrochemical impedance spectroscopy, and scanning electron microscopy measurements indicated that AO was successfully immobilized on the PPy–MWCNT composites. The optimization of the biosensor parameters, including the working potential, pH, and temperature, was investigated in detail. The proposed biosensor showed a linear range of 5 × 10^?5 to 2 × 10^?2 M with a detection limit of 0.3 μM, a sensitivity of 25.9 mA mM^?1 cm^?2, and a current response time less than 20 s under the optimized conditions. The apparent Michaelis–Menten constant together with the apparent activation energy indicated that the proposed biosensor exhibited a high bioaffinity and a good enzyme activity. In addition, the biosensor also showed good operational and storage stabilities. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Electropolymerization and energy storage of poly[Ni(salphen)]/MWCNT composite materials for supercapacitors

Ni(salphen), a Schiff base ligand compound, was synthesized and electropolymerized on multiwalled carbon nanotube (MWCNT) electrodes in an acetonitrile solution via the pulse potentiostatic method and then applied as a supercapacitor electrode material. The polymerization mode was investigated through methyl replacement in the para‐position of phenyl rings in the Ni(salphen) monomer, and it was found that the Ni(salphen) monomers would polymerize by the generation of C? C bonds between the phenyl rings in the para‐position of the phenol moieties. The optimum condition for polymerization was evaluated, and when the polymerization time was 8 min, poly[Ni(salphen)] exhibited a specific capacitance up to 200 F g^?1 at a current density of 0.1 mA cm^?2, and the capacitance remains at 164 F g^?1 at 20 mA cm^?2. The energy density of the poly[Ni(salphen)] electrode reached 40 Wh kg^?1 at 0.1 mA cm^?2, about eight times greater than for a pure MWCNT electrode. Electrochemical performances were investigated, and the composites showed good redox property and ion transfer capability. This work showed that Ni(salphen) may be an attractive material in supercapacitors© 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44464.     

High cycling stability and well printability poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate)/multi‐walled carbon nanotube nanocomposites via in situ polymerization applied on electrochromic display

A high cycling stability material and an additive manufacturing method are reported for the fabrication of solid electrochromic devices. The poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate)/multi‐walled carbon nanotube (PEDOT:PSS/MWCNT) nanocomposites were synthesized via in situ polymerization. A carboxymethyl cellulose gel was used as the ink vehicle for screen printing. The electrochromic (EC) performance of films patterned by screen printing was also examined. The results of characterization indicate that strong interfacial interactions occurred between PEDOT:PSS and the MWCNTs and the MWCNTs formed a network in these conducting polymers film, so the composite was more conductive than pure PEDOT:PSS. Devices containing PEDOT:PSS/MWCNTs were more stable after 1000 cycles, exhibited higher rate of ion exchange and faster increases in current. The composite containing 0.3 wt % MWCNTs also had a 23% higher color contrast (ΔE*) than pure PEDOT:PSS at 2.5 V applied voltages. The EC inks with well printability not only can be used to print large area films, but also can print fine lines and pixel‐type dots in displays. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45943.