Poly(acrylonitrile-co-itaconic acid)–poly(3,4-ethylenedioxythiophene) and poly(3-methoxythiophene) nanoparticles and nanofibres

This work aimed to produce poly(acrylonitrile-co-itaconic acid) (P(AN-co-IA)) nanocomposites with poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3-methoxythiophene) (PMOT). An anionic surfactant sodium dodecyl benzene sulphonate was used in emulsion polymerization for nanocomposite production. Incorporations of PEDOT and PMOT on the nanoparticles were characterized by scanning electron microscopy (SEM), atomic force microscopy, Fourier transform infrared-attenuated total reflectance spectroscopy and ultra-violet spectroscopy. These nanoparticles were blended with PAN and the blends were electrospun to produce P(AN-co-IA)–polythiophene-derivative-based nanofibres, and the obtained nanofibres were characterized by SEM and energy dispersive spectroscopy. In addition, electrochemical impedance studies conducted on nanofibres showed that PEDOT and PMOT in matrix polymer P(AN-co-IA) exhibited capacitive behaviour comparable to that of ITO–PET. Their capacitive behaviour changed with the amount of electroactive polymer.     

New hybrid active power filter for harmonic current suppression and reactive power compensation

In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.     

Nanoscale surface morphology and monomer concentration dependence on impedance of electrocoated 2,2-dimethyl-3,4-propylene-dioxythiophene on carbon fiber microelectrode

Poly(2,2-Dimethyl-3,4-propylenedioxythiophene) (PProDOT-Me2) thin films have been cyclovoltametrically coated onto carbon fiber microelectrode (CFME) as an active functionalized microelectrode. An electrochemical impedance spectroscopic study on the prepared electrodes is reported in this paper which electropolymerization performed under different initial monomer concentrations. The electrochemical impedance data fitted to equivalent circuit model, used to find out numerical values of the proposed components. Effect of the parameters on the capacitive behavior of the (PProDOT-Me2) coated carbon fiber microelectrode and morphology of films obtained by AFM and SEM was discussed. Highly porous coating was obtained at 100 mV/s scan rate and 10 cycles. EDX and ATR-FTIR results indicated the doping of anion of electrolyte due to formation of polaronic and bipolaronic sites. The presence of surface functional groups were determined by ATR-FTIR. Nanoscale conjugated polymer modified carbon fiber microelectrodes exhibited high capacitance of approximately 90 degrees phase angle, and vertical line in Nyquist plot. The capacitive behavior of CFME was increased by this very thin film coating of PProDOT-Me2. The electroactivity of Poly 2,2-Dimethyl-3,4-propylenedioxythiophene on the carbon fiber microelectrode open the possibility of using these coated electrodes for electrochemical microsupercapacitors and biosensor electrodes.     

Structural definitions for soluble portions of polyacrylamides synthesized with Ce(IV)–chelating agent redox systems

Polymerizations of acrylamide initiated by ceric ammonium nitrate and ceric sulphate in combination with nitrilotriacetic acid, ethylene diamine tetraacetic acid, diethylene triamine pentaacetic acid and 1,2-cyclohexane dinitrilotetraacetic acid were studied in aqueous nitric acid and sulphuric acid solutions at 55°C in the presence of air. The experimental results can be explained by assuming that the complexes of Ce(III) with sulphate and nitrate ions, Ce(SO₄)_n^{x(+ or −}) and Ce(NO₃)_n^{x(+ or −}), have different reactivities in the reactions. FTIR and UV spectra of the polymers, together with conductometric and gravimetric measurements, clearly showed that in the case of sulphato-cerate complexes, there were complexes not only on the end-groups but also on amide groups within the chain. Furthermore, it was observed that the stabilities of the primary radical sources generated by the redox pairs used in this work depend on the anion type and concentration of the acid and oxidation agent.     

Electrochemical composite formation of thiophene and N-methylpyrrole polymers on carbon fiber microelectrodes: Morphology,characterization by surface spectroscopy,and electrochemical impedance spectroscopy

Electrochemical composite thin film formation (∼0.6–0.7 μm) of thiophene and N-methylpyrrole on carbon fiber microelectrodes (diameter ∼7 μm) was carried out by cyclic voltammetry in order to understand and improve the surface properties and capacitance behaviour of carbon fibers. Carbon fiber microelectrodes were coated with polythiophene and N-methylpyrrole was electrografted onto the thiophene electrode. The electrocoated carbon fiber surface mophology was characterized by scanning electron microscopy and atomic force microscopy and by FTIR-reflectance spectroscopy for their composition. The effect of monomer concentration and scan number on electropolymerization has also been investigated. The impedance behaviour of composite electrodes was characterized by electrochemical impedance spectroscopy. The composite of polythiophene and poly-N-methylpyrrole exhibits better charge storage properties than polythiophene coated carbon fiber microelectrodes.     

Transparent poly(methyl methacrylate‐co‐butyl acrylate) nanofibers

Nanofibers of n‐Butyl Acrylate/Methyl Methacrylate copolymer [P(BA‐co‐MMA)] were produced by electrospinning in this study. P(BA‐co‐MMA) was synthesized by emulsion polymerization. The structural and thermal properties of copolymers and electrospun P(BA‐co‐MMA) nanofibers were analyzed using Fourier transform infrared spectroscopy–Attenuated total reflectance (FTIR–ATR), Nuclear magnetic spectroscopy (NMR), and Differential scanning calorimetry (DSC). FTIR–ATR spectra and NMR spectrum revealed that BA and MMA had effectively participated in polymerization. The morphology of the resulting nanofibers was investigated by scanning electron microscopy, indicating that the diameters of P(BA‐co‐MMA) nanofibers were strongly dependent on the polymer solution dielectric constant, and concentration of solution and flow rate. Homogeneous electrospun P(BA‐co‐MMA) fibers as small as 390 ± 30 nm were successfully produced. The dielectric properties of polymer solution strongly affected the diameter and morphology of electrospun polymer fibers. The bending instability of the electrospinning jet increased with higher dielectric constant. The charges inside the polymer jet tended to repel each other so as to stretch and reduce the diameter of the polymer fibers by the presence of high dielectric environment of the solvent. The extent to which the choice of solvent affects the nanofiber characteristics were well illustrated in the electrospinning of [P(BA‐co‐MMA)] from solvents and mixed solvents. Nanofiber mats showed relatively high hydrophobicity with intrinsic water contact angle up to 120°. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4264–4272, 2013     

Electropolymerization, characterization and corrosion performance of poly(N-ethylaniline) on copper

Poly(N-ethylaniline) (PNEA) coatings were grown by cyclic voltammetry technique on copper from 0.1 M N-ethylaniline (NEA) in 0.3 M oxalic acid solution. The optimum conditions (e.g. upper potential limit, scan rate and cycle number) effect on corrosion performance of synthesized PNEA films were determined in order to obtain best protection results against corrosion. The electrodeposited coatings were characterized by cyclic voltammetry (CV), Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) spectroscopy and scanning electron microscopy (SEM). Redox parameters were found after electrochemical tests and results of stability tests of these films impart an electroactive behavior that is composed of both diffusion control and thin film behavior. In addition, corrosion performance of PNEA coatings were investigated in 0.1 M H₂SO₄ by Tafel extrapolation and electrochemical impedance spectroscopy (EIS) techniques.     

The polymerization of acrylamide initiated with CE(IV) and KMNO4 redox systems in the presence of glycine

Glycine-Ce(IV) salts and −KMnO₄ initiator systems were used for the polymerization of acrylamide, resulting in water-soluble polyacrylamide, which contains amino acid end groups. The dependence of polymerization yields and molecular weights of polymers on the mole ratio of acrylamide monomer to glycine, the polymerization time, the temperature, and the concentration of sulfuric acid were investigated. The decrease in the mole ratio of acrylamide to glycine resulted in a decrese in the molecular weight, and an increase in the yield of acrylamide polymer, which contains a glycine end group. With increasing acid concentration of the polymeric solution, the polymerization yield and the molecular weight of polymer decrease. Ce(IV) and Mn(IV) reduced to Ce(III) and Mn(II) in the polymerization reaction. The amounts of Ce(III) and Mn(II) bound to polymer were determined. The composition of the polymerization product was investigated and a bimodal character of the molecular weight distribution was observed. The mechanism of this phenomena is discussed. © 1996 John Wiley & Sons, Inc.     

Effect of Magnetic Field on Radial Dopant Segregation in Crystal Growth

A three-dimensional time-dependent computational model is developed to simulate the melt flow and the dopant transport during the growth of Si_1?x Ge _x semiconductor crystals. The effect of static magnetic fields of different orientations on radial segregation of dopant is analyzed. It is observed that the flow oscillations are damped and flow becomes steady for both horizontal and vertical applied magnetic fields as the Hartman number increases. It is found that there is an optimum value of Hartman number for each Rayleigh number beyond which little or no improvement in uniformity of concentration can be obtained at the growth interface.