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.     

Electrically conductive composites based on epoxy resin containing polyaniline–DBSA‐ and polyaniline–DBSA‐coated glass fibers

Four kinds of polyaniline (PANI)‐coated glass fibers (GF–PANI) combined with bulk PANI particles were synthesized. GF–PANI fillers containing different PANI contents were incorporated into an epoxy–anhydride system. The best conductivity behavior of the epoxy/GF–PANI composites was obtained with a GF–PANI filler containing 80% PANI. Such a composite shows the lowest percolation threshold at about 20% GF–PANI or 16% PANI (glass fiber‐free basis). The PANI‐coated glass fibers act as conductive bridges, interconnecting PANI particles in the epoxy matrix, thus contributing to the improvement of the conductivity of the composite and the lower percolation threshold, compared with that of a epoxy/PANI–powder composite. Particularly, the presence of glass fibers significantly improves the mechanical properties, for example, the modulus and strength of the conductive epoxy composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1329–1334, 2004     

Synthesis and electrorheological properties of polyaniline‐coated barium titanate composite particles

Polyaniline‐coated barium titanate composite particles were synthesized by surface grafting polymerization, in which five silane coupling agents with different terminal groups were used. The structure of composite particles was characterized by SEM, XRD, FTIR, and TGA, and the electrorheological properties were tested by rotational rheometer. The results show that polyaniline was coated on the surface of barium titanate particles to form the shell‐core structure. The yield stress of the electrorheological fluids based on polyaniline‐coated barium titanate composite particles is higher than that of polyaniline and barium titanate. Compared with PANI‐based electrorheological fluids (ERFs), the composite particles‐based ERFs have lower field‐off viscosity due to the molecular interaction. The yield stress of the ERFs, as well as density of the composite particles, was affected by the groups at terminal of silane coupling agents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of conducting polyaniline‐activated carbon nanocomposites

Conducting polyaniline (PAni)/activated carbon (AC) nanocomposites were synthesized by the in situ chemical polymerization method. The resultant shell–core PAni–AC nanocomposites were characterized by elemental analysis, Fourier transform infrared, scanning electron microscopy, thermal gravimetric analysis, X‐ray diffraction, and transmission electron microscopy. We did not observe any significant chemical interaction between the PAni and AC, only core–shell coupling between the AC and the tightly coated polymer chain was revealed. Measurement of the physical properties showed that the incorporation of conducting PAni on to AC particles during chemical synthesis increased electrical conductivity and thermal stability by several orders of magnitude to that of the pristine PAni powders. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1973–1977, 2007     

Enhancing the electrical conductivity of carbon black/graphite nanoplatelets: Poly(ethylene‐butyl acrylate) composites by melt extrusion

The influence of processing parameters such as screw geometry, temperature profile, and screw speed on the electrical properties of hybrid composites consisting of graphite nanoplatelets and carbon black in ethyl butyl acrylate was studied. Two different screws were used to compound the hybrid composites at two different temperatures and two different screw speeds. A beneficial effect was noted with regard to the electrical properties when adding nanoplatelets to the filler system. The cause could be a synergistic effect due to the difference in particle shape of the two fillers. Lower percolation thresholds were obtained with the conventional screw due to less breakage of the graphite nanoplatelets compared to the barrier screw. No significant changes of the electrical properties were observed when changing the temperature profiles or the screw speeds. Furthermore, the melt viscosity of the compounds was not appreciably affected at the rather low filler contents used here. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42897.     

Synthesis and characterization of a ferrocene‐modified,polyaniline‐like conducting polymer

A novel monomer called 1,1′‐ferrocenediacyl anilide (FcA) was synthesized from ferrocene (Fc). Copolymerization was carried out between FcA and aniline (ANI) by an electrochemical method. The novel monomer and copolymer were characterized with ¹H‐NMR, Fourier transform infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–vis) spectroscopy. The hydrogen protons of the benzene ring were moved to a low field in ¹H‐NMR, and the absorption band of N?Q?N (where Q is the quinoid ring) appeared in the FTIR spectrum of the polymer. The peaks of both Fc and the π–π* electronic transition in the UV–vis spectra were redshifted. The results indicate that the copolymer mainly existed as a highly delocalized conjugated system. X‐ray diffraction analysis established further proof, and the process of electrochemical deposition was observed by scanning electron microscopy. The optimal synthesis conditions of the copolymer were determined through changes in the monomer molar ratios and the scan rate. The ideal performance of the copolymer was gained when the monomer molar ratio between FcA and ANI was 1:4 and the scan rate was 50 mV/s. Furthermore, the electrochemical performances were tested in detail by cyclic voltammetry, galvanostatic charge–discharge testing, and electrochemical impedance spectroscopy. The results show that the specific capacitance of poly(1,1′‐ferrocenediacyl anilide‐co‐aniline) increased up to 433.1 F/g at 0.5 A/g, the diffusion resistance was very small, and the durability was good enough. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43217.     

In situ fabrication of polyaniline‐silver nanocomposites using soft template of sodium alginate

Polyaniline (PANI)‐Ag nanocomposites were synthesized by in situ chemical polymerization approach using ammonium persulfate and silver nitrate as oxidant. Characterizations of nanocomposites were done by ultraviolet–visible ( UV–vis), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM). UV–vis, XRD and FTIR analysis established the formation of PANI/Ag nanocomposites and face‐centered‐cubic phase of silver. PANInanofibers were of average diameter ～ 30 nm and several micrometers in length. Morphological analysis showed that the spherical‐shaped silver nanoparticles decorate the surface of PANI nanofibers. Silver nanoparticles of average diameter ～ 5–10 nm were observed on the TEM images for the PANI‐Ag nanocomposites. Such type of PANI‐Ag nanocomposites can be used as bistable switches as well as memory devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Potassium persulfate-mediated preparation of conducting polypyrrole/polyacrylonitrile composite fibers: Humidity and temperature-sensing properties

Conducting polypyrrole (PPy)/polyacrylonitrile (PAN) composite fibers were prepared by the polymerization of pyrrole in the presence of PAN fibers with potassium persulfate in an acidic aqueous solution. We obtained composite fibers containing concentrations of PPy as high as 1.14% and having surface resistivities as low as 0.6 kΩ/cm² by changing the polymerization parameters, including the temperature and concentrations of pyrrole and oxidant. The tensile strength of 10.02 N/m² and breaking elongation of 32.68% for the pure PAN fiber increased up to 10.45 N/m² and 33.23%, respectively, for the composite fiber containing 0.13% PPy. The change in the resistivity of the PPy/PAN composite fiber during heating–cooling cycles in the temperature range of +5 to 120°C was examined. Scanning electron microscopy and optical microscopy images of the composite fibers showed that the PPy coating was restricted to the surfaces of the PAN fibers. Surface resistivity measurements, Fourier transform infrared spectroscopy, and thermogravimetric analysis techniques were also used to characterize the composite fibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of conductive latex based on polyaniline–perlite composite

The development of polymers with high electrical conductivity has attracted significant research interest because of the possibility of new applications. Electrically conductive latexes have drawn the attention of scientists over the last few years. The present work reports the preparation of composites in which polyaniline was deposited onto perlite particles by oxidative polymerization. Electrically conductive latex was prepared by homogeneously mixing submicron conductive composites with poly(vinylacetate‐co‐butylacrylate‐co‐butylversitate) resin in a desirable ratio. The conductivity of composites and latex was measured by a standard four‐point probe. Morphology of composites was studied by scanning electron microscopy. Adhesion and electroactivity of the latex were also investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2528–2531, 2004     

X-ray photoelectron spectroscopy of conducting polyaniline and polyaniline–polystyrene blends

Conductive polyaniline solutions were chemically prepared using bis (2-ethylhexyl) hydrogen phosphate (DiOHP) as the dopant chemical species. The codissolution method leads to conductive polyaniline–polystyrene (PANI–PSt) composites with good mechanical properties. The electronic structure of both conducting PANI films and PANI–PSt blends was investigated by X-ray photoelectron spectroscopy, which allowed one to quantify the proportion of benzenoid amine, quinoid imine, and protonated units. Blending polyaniline with PSt does not involve important modifications in the polymer electronic structure. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1209–1214, 1998     

Electrochemical preparation and characterization of conducting copolymer/silica composite

A composite based on organic copolymer and inorganic oxide, polyaniline/poly o‐toluidine/silica (PANI/POT/SiO₂), has been synthesized successfully by a simple electrochemical method. The composite film was found to be deposited on a Pt substrate by sweeping the potential between ?0.2 and +1.0 V versus a saturated calomel electrode with a scan rate of 100 mV/s. The polymeric composite film thus obtained was characterized by scanning electron microscopy, infrared spectroscopy, conductance measurement, and cyclic voltammetry techniques. Incorporation of silica in the copolymer results a clear difference in surface morphology compared with the bulk homo‐ and copolymers. Further evidence of silica in the composite was achieved by infrared spectral analysis. Indeed, a chemical analysis of the composite matrix showed a content of as high as 25% SiO₂ in the composite thus prepared. Based on the results of cyclic voltammetric analysis, the composite electrode as prepared was found to show good electrochemical stability even at high positive potentials. It also exhibited excellent electroactivity even after incorporation of silica in the matrix. The electroactive composite film was thus examined as electrode modifier to study the redox behavior of ferrous/ferric (Fe²⁺/Fe³⁺) and hydroquinone/benzoquinone (H₂Q/Q) couples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hybrid polyaniline–TiO2 nanocomposite Langmuir–Blodgett thin films: Self‐assembly and their characterization

Polyaniline (PANi)–titanium dioxide (TiO₂) nanocomposite materials were prepared by chemical polymerization of aniline doped with TiO₂ nanoparticles. Surface pressure–area (π‐A) isotherms of these nanocomposites show phase transformations in the monolayer during compression process. Multiple isotherms indicate that the monolayer of the nanocomposite material can retain its configuration during compression‐expansion cycles. Langmuir–Blodgett thin films of PANi–TiO₂ nanocomposite were deposited on the quartz and indium tin oxide coated conducting glass substrates. Fourier transfer infrared spectroscopy and UV–visible spectroscopy study indicates the presence of TiO₂ in PANi, whereas X‐ray Diffraction study confirmed the anatase phase of TiO₂ and particle size (～nm) of PANi–TiO₂. The morphology of Langmuir–Blodgett films of these nanocomposites was also characterized by atomic force microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41386.     

Electrically conducting polyaniline–poly(acrylic acid) blends

We report an electrically conducting polyaniline–poly(acrylic acid) blend coatings prepared by mixing the emeraldine base (EB) form of polyaniline (PANI) and poly(acrylic acid) (PAA) aqueous solution. The samples show a moderate electrical conductivity σ. If they are immersed in an HCl aqueous solution, the conductivity of the samples is increased by two or three orders of magnitude and their thermal stability is also improved. Optical transmittance spectra show a complete protonation of PANI–PAA blends after immersion in HCl aqueous solution. Fourier transform infrared spectroscopy studies indicate that the better thermal stability of σ could come from the more stable protonated imine nitrogen ions. A low percolation threshold phenomenon is observed in PANI–PAA blends, from a strong interaction between the carboxylic acid groups of PAA and the nitrogen atoms of PANI. © 1998 SCI.     

One‐step oxidation of aniline by peroxotitanium acid to polyaniline–titanium dioxide: A highly stable electrode for a supercapacitor

In this study, to make a stable electrode material for a supercapacitor, we selected a polyaniline and titanium dioxide (TiO₂) hybrid material. Peroxotitanium acid was used to oxidize aniline in the presence of sulfuric acid to a poly(aniline sulfate) salt–titanium oxide composite in one step. IR, X‐ray diffraction, and energy dispersive X‐ray analysis (EDAX) analyses supported the formation of the composite. The poly(aniline sulfate) salt–titanium oxide composites (50 wt % each) showed an amorphous, flakelike morphology having a conductivity value of 8 × 10^?3 S/cm with an excellent yield and stability (300°C).This composite material in the cell configuration showed a specific capacitance of 320 F/g at a 0.33 A/g discharge current density. Thirty thousand charge–discharge (CD) cycles at a heavy CD current density of 3.3 A/g were carried out on the supercapacitor cell. The values of equivalent series resistance (ESR) (8–9 Ω) and efficiency (100–98%) were found to be independent of the cycle number with an excellent retention capacity of 83%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41711.     

Electrochemical behaviors of polyaniline–poly(styrene‐sulfonic acid) complexes and related films

This research focuses on the syntheses of polyaniline with poly(styrenesulfonic acid) and their electrochemical behavior, including absorbance behavior and electrochemical response time of polyaniline‐poly(styrenesulfonic acid) [PANI–PSSA]. The complexes PANI–PSSA were prepared by electrochemical polymerization of monomer (aniline) with PSSA, using indium‐tin oxide (ITO) as working electrode in 1M HCl solution. Polyaniline (PANI), poly(o‐phenetidine)–poly(styrenesulfonic acid) [POP–PSSA], and poly(2‐ethylaniline)–poly(styrenesulfonic acid) [P2E‐PSSA] also were prepared by electrochemical polymerization and to be the reference samples. The products were characterized by IR, VIS, EPR, water solubility, elemental analysis, conductivity, SEM, and TEM. IR spectral studies shows that the structure of PANI–PSSA complexes is similar to that of polyaniline. EPR and visible spectra indicate the formation of polarons. The morphology of the blend were investigated by SEM and TEM, which indicate the conducting component and electrically conductive property of the polymer complexes. Elemental analysis results show that PANI–PSSA has a nitrogen to sulfur ratio (N/S) of 38%, lower than that for POP–PSSA (52%) and P2E–PSSA (41%). Conductivity of the complexes are around 10^?2 S/cm, solubility of PANI–PSSA in water is 3.1 g/L. The UV‐Vis. absorbance spectra of the hybrid organic/inorganic complementary electro‐chromic device (ECD), comprising a polyaniline–poly(styrenesulfonic acid) [PANI–PSSA] complexes and tungsten oxide (WO₃) thin film coupled in combination with a polymer electrolyte poly(2‐acrylamido‐2‐methyl‐propane‐sulfonic acid) [PAMPSA]. PANI–PSSA microstructure surface images have been studied by AFM. By applying a potential of ～3.0 V across the two external ITO contacts, we are able to modulate the light absorption also in the UV‐Vis region (200–900 nm) wavelength region. For example, the absorption changes from 1.20 to 0.6 at 720 nm. The complexes PANI–PSSA, POP–PSSA, and P2E–PSSA were prepared by electrochemical polymerization of monomer (aniline, o‐phenetidine, or 2‐ethylaniline) with poly(styrenesulfonic acid), using ITO as working electrode in 1M HCl solution, respectively. UV‐Vis spectra measurements shows the evidences for the dopped polyaniline system to be a highly electrochemical response time, recorded at the temperature 298 K, and the results were further analyzed on the basis of the color‐ discolor model, which is a typical of protontation systems. Under the reaction time (3 s) and monomer (aniline, o‐phenetidine, 2‐ethylaniline) concentration (0.6M) with PSSA (0.15M), the best electrochemical color and discolor time of the PANI–PSSA is slower than POP–PSSA complexes (125/125 ms; thickness, 3.00 μm) and P2E–PSSA complexes. Under the same thickness (10 μm), the best electrochemical color and discolor time of the PANI–PSSA complexes is 1500/750 ms, that is much slower than P2E–PSSA complexes (750/500 ms) and POP–PSSA complexes (500/250 ms). In film growing rate, the PANI–PSSA complexes (0.54 μm/s) are slower than P2E–PSSA complexes (0.79 μm/s) and POP–PSSA complexes (1.00 μm/s), it can be attributed to the substituted polyaniline that presence of electro‐donating (? OC₂H₅ or ? C₂H₅₎ group present in aniline monomer. The EPR spectra of the samples were recorded both at 298 K and 77 K, and were further analyzed on the basis of the polaron–bipolaron model. The narrower line‐width of the substituted polyaniline complexes arises due to polarons; i.e., it is proposed that charge transport take place through both polarons and bipolarons, compared to their salts can be attributed to the lower degree of structural disorder, the oxygen absorption on the polymeric molecular complexes, and due to presence of electro‐donating (? OC₂H₅ or ? C₂H₅) group present in aniline monomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:4023–4044, 2006     

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.     

Freestanding chemiresistive polymer composite ribbons as high-flux sensors

Chemiresistive polymer composite ribbons that function as chemical detectors were produced from solution-cast films of polymers and carbon composites. An array with multiple polymer sensor threads was exposed to dimethyl methyl phosphonate, a nerve agent simulant, and different interferents in the vapor phase. Principal component analysis was used to differentiate between the analytes. The response of the ribbon sensors as a function of the carbon composite and the host polymer source was investigated. The freestanding threads/sensors were mounted into a cell perpendicular to the gas flow to provide little pressure drop and were imbedded into fabrics to provide an example of a small, low-cost, wearable chemical sensor. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Conductive polyaniline–polythiophene/poly(ethylene terephthalate) composite fiber: Effects of pH and washing processes on surface resistivity

A conductive polyaniline (PAn)–polythiophene (PTh)/poly(ethylene terephthalate) (PET) composite fiber was prepared by polymerization of aniline and thiophene in the presence of PET fibers in an organic medium with FeCl₃. The effects of polymerization conditions, such as polymerization medium, mol ratios of aniline/thiophene and FeCl₃/aniline‐thiophene as well as polymerization temperature and time, were investigated on PAn–PTh content (%) and surface resistivity of the composite. The composite with the lowest surface resistivity (1.30 MΩ/cm²) was obtained by polymerization of aniline and thiophene (1/3 mol ratio) in acetonitrile/chloroform (1/5 volume ratio) at 20°C. The surface resistivity of the PAn–PTh/PET composite containing 4.8% PAn–PTh was increased from 1.9 MΩ/cm² to 270 MΩ/cm² at pH 11. The washing durability of the composites was determined with domestic and commercial laundering processes by monitoring the surface resistivity and morphology. The composite was also characterized with FTIR, TGA, elemental analysis, optic microscope and SEM techniques. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41979.     

Electrospun composite nanofibers of poly (vinylidene fluoride‐trifluoroethylene)/polyaniline‐polystyrene sulfonic acid

Nanofibers of poly(vinylidene fluoride‐trifluoroethylene)/polyaniline‐polystyrene sulfonic acid (PVDF‐TrFE/PANi‐PSSA) were fabricated in air at room temperature using electrospinning, with the thinnest fiber having a diameter of ～ 6 nm. This is a cheap, fast, and reliable process for generating PVDF‐TrFE/PANi‐PSSA composite nanofibers. The presence of conducting PANi‐PSSA increased the charge density of the solution and assisted in the fabrication of PVDF‐TrFE nanofibers at low polymer concentrations in dimethylformamide without the beading effect. Ultraviolet and visible spectroscopy showed that PANi‐PSSA was well incorporated into the PVDF‐TrFE solution with no polymer segregation or degradation. A scanning electron microscope was used for morphological characterization of the fibers and a profilometer used to determine the fiber diameter. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal behavior of polyaniline films and polyaniline–polystyrene blends

In this article, a study of the thermal behavior of polyaniline films and polyaniline–polystyrene blends is presented. Transport measurements (electrical conductivity and thermoelectric power) at high temperature and thermogravimetric analysis show that an irreversible degradation is observed near 450 K for films doped with DiOHP and near 500 K for films doped with CSA. In both cases, the thermoelectric power is the most sensitive parameter to electrical degradation during the heating of conducting films. Electrical conductivity measurements during heating–cooling cycles show a diminution of the room temperature conductivity after evaporation of the solvent (water, m‐cresol). A model of cluster with a variable diameter allows interpreting this phenomenon by assuming the existence of a sensitive frontier to the solvent at the periphery of conducting clusters. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1848–1855, 2002; DOI 10.1002/app.10468