pH electrodes constructed from polyaniline/zeolite and polypyrrole/zeolite conductive blends

A new type of solid state electrodes sensitive to pH changes is described, in which the chemical‐sensitive layer consists of Pt microparticles deposited on a conducting polymer (polyaniline, polypyrrole) blend containing 22.7% w/w zeolite. These sensors are stable in aqueous electrolyte solutions of low pH value at temperatures up to 45°C with response time in seconds. At 25°C, sensor sensitivity was ?310 ± 40 mV/pH and ?1300 ± 100 mV/pH for polyaniline and polypyrrole blends, respectively. Interferences appear to be acceptably small. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1853–1856, 2006     

Dopant induced effect on electrocatalytic reduction of nitrobenzene using conducting polypyrrole thin film electrodes

Conducting polypyrrole electrodes were prepared by electrochemical polymerization of pyrrole on vacuum‐metallized glass substrates. These electrodes were modified by doping with a range of metal halides as dopant ions having different electronegativity. Electrochemical reduction of nitrobenzene using these electrodes was studied by means of cyclic voltammetry technique in acetonitrile medium containing aqueous HClO₄ (0.1M) as supporting electrolyte. It was found that the electronegativity of the dopant ion played a very important role in the electrocatalytic activity. Polypyrrole doped with nickel chloride gave the highest anodic current at the reduction potential of nitrobenzene. The results were explained on the basis of charge transfer efficiency at the electrode–electrolyte interface, which was associated with the acceptor state created by the dopant in the semi‐conducting polymer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Studies of solvent effect on the conductivity of 2‐mercaptopyridine‐doped solid polymer blend electrolytes and its application in dye‐sensitized solar cells

Solvents and electrolytes play an important role in the fabrication of dye‐sensitized solar cells (DSSCs). We have studied the poly(ethylene oxide)‐poly(methyl methacrylate)‐KI‐I₂ (PEO‐PMMA‐KI‐I₂) polymer blend electrolytes prepared with different wt % of the 2‐mercaptopyridine by solution casting method. The polymer electrolyte films were characterized by the FTIR, X‐ray diffraction, electrochemical impedance and dielectric studies. FTIR spectra revealed complex formation between the PEO‐PMMA‐KI‐I₂ and 2‐mercaptopyrindine. Ionic conductivity data revealed that 30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I₂ electrolyte can show higher conductivity (1.55 × 10^?5 S cm^?1) than the other compositions (20, 40, and 50%). The effect of solvent on the conductivity and dielectric of solid polymer electrolytes was studied for the best composition (30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I₂) electrolyte using various organic solvents such as acetonitrile, N,N‐dimethylformamide, 2‐butanone, chlorobenzene, dimethylsulfoxide, and isopropanol. We found that ac‐conductivity and dielectric constant are higher for the polymer electrolytes processed from N,N‐dimethylformamide. This observation revealed that the conductivity of the solid polymer electrolytes is dependent on the solvent used for processing and the dielectric constant of the film. The photo‐conversion efficiency of dye‐sensitized solar cells fabricated using the optimized polymer electrolytes was 3.0% under an illumination of 100 mW cm^?2. The study suggests that N,N‐dimethylformamide is a good solvent for the polymer electrolyte processing due to higher ac‐conductivity beneficial for the electrochemical device applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42489.     

ABTS•+ scavenging activity of polypyrrole,polyaniline and poly(3,4‐ethylenedioxythiophene)

Although many methods are available for the evaluation of the antioxidant capacity of samples presented in the liquid state, typically food and beverages, to date only the 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) assay has been applied to the measurement of the antioxidant capacity of solid samples such as active packaging materials. A modified 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) assay has been successfully developed for the measurement of the antioxidant capacity of conducting polymer powders. The ABTS^?+ radical scavenging activity of polypyrrole (PPy), polyaniline (PANI) and poly(3,4‐ethylenedioxythiophene) (PEDOT) powders was compared. The ranking order for greatest antioxidant capacity among the conducing polymer powders was PANI > PPy > PEDOT. The reduced forms of all the three conducting polymer samples were found to show greater radical scavenging activity than their as‐prepared partially oxidized forms. The modified ABTS assay is a simple, rapid and sensitive method for evaluating the antioxidant capacity of conducting polymer powders. The method is also suitable for composite antioxidant materials comprising a conducting polymer and a conventional packaging polymer. Copyright © 2010 Society of Chemical Industry     

Analysis of the effect of polypyrrole synthesis conditions on its capacity to reduce hexavalent chromium

This paper reports the capacity of polypyrrole to reduce toxic hexavalent chromium (Cr(VI)). The influence of using different electrolytes during the polymer's synthesis has been studied. To improve the reduction of Cr(VI), the parameters considered were the polypyrrole morphology and the amount of conducting polymer. Polypyrrole obtained by cyclic voltammetry at a low sweep rate using KBr as supporting electrolyte showed better performance for Cr(VI) reduction compared to coatings obtained by constant potential or cyclic voltammetry at high sweep rates.     

Bifunctional poly(ethylene glycol) based crosslinked network polymers as electrolytes for all‐solid‐state lithium ion batteries

Polymer electrolyte based lithium ion batteries represent a revolution in the battery community due to their intrinsic enhanced safety, and as a result polymer electrolytes have been proposed as a replacement for conventional liquid electrolytes. Herein, the preparation of a family of crosslinked network polymers as electrolytes via the ‘click‐chemistry’ technique involving thiol‐ene or thiol‐epoxy is reported. These network polymer electrolytes comprise bifunctional poly(ethylene glycol) as the lithium ion solvating polymer, pentaerythritol tetrakis (3‐mercaptopropionate) as the crosslinker and lithium bis(trifluoromethane)sulfonimide as the lithium salt. The crosslinked network polymer electrolytes obtained show low T_g, high ionic conductivity and a good lithium ion transference number (ca 0.56). In addition, the membrane demonstrated sterling mechanical robustness and high thermal stability. The advantages of the network polymer electrolytes in this study are their harmonious characteristics as solid electrolytes and the potential adaptability to improve performance by combining with inorganic fillers, ionic liquids or other materials. In addition, the simple formation of the network structures without high temperatures or light irradiation has enabled the practical large‐area fabrication and in situ fabrication on cathode electrodes. As a preliminary study, the prepared crosslinked network polymer materials were used as solid electrolytes in the elaboration of all‐solid‐state lithium metal battery prototypes with moderate charge–discharge profiles at different current densities leaving a good platform for further improvement. © 2018 Society of Chemical Industry     

Hydrolytic degradation of polyamides based on L-tartaric acid and diamines

We have studied the deposition of thin films of a conducting polymer, polypyrrole, onto printed circuit boards (PCBs). Film formation occurs as a result of the in situ polymerization of pyrrole monomer using a 1 : 1 FeCl³/5-sulfosalicylic acid oxidant complex in aqueous solution. We have optimized the polymerization conditions in order to coat a large number of PCBs with a single polymerization bath, while at the same time maintaining the quality of the conducting polymer coating (i.e., keeping its surface resistance below 10⁴ Ω per square). These improvements were achieved simply by controlling the initial oxidant–monomer mole ratio such that the oxidant is always present in significant excess. We have also examined the formation of thick polypyrrole layers obtained from the progressive buildup of thin layers. The morphology and film thickness of these polypyrrole coatings have been studied by scanning electron microscopy. Some preliminary electroplating experiments using these polypyrrole–PCB composites are also described. © 1995 John Wiley & Sons, Inc.     

Morphology and ionic conductivity of thermoplastic polyurethane electrolytes

Thermoplastic polyurethane (TPU) with a mixture of soft segments [poly(ethylene glycol) (PEG) and poly(tetramethylene glycol) (PTMG)], denoted TPU‐M, was prepared as an ion‐conducting polymer electrolyte. TPUs with PEG and PTMG as soft segments were also synthesized individually as polymer electrolytes. The changes in the morphology and ion conductivity of the phase‐segregated TPU‐based polymer electrolytes as a function of the lithium perchlorate concentration were determined with differential scanning calorimetry, Fourier transform infrared spectroscopy, alternating‐current impedance, and linear sweep voltammetry measurements. Both solid and gelatinous polymer electrolytes were characterized in this study. The effect of temperature on conductivity was studied. The conductivity changes revealed the combined influence of PTMG and PEG units in TPU‐M. The swelling characteristics in a liquid electrolyte and the dimensional stability were evaluated for the three TPUs. Because of its dimensional stability and ionic conductivity, the TPU system containing both PEG and PTMG as soft segments was found to be more suitable for electrolyte applications. A room‐temperature conductivity of approximately 1 × 10^?4 was found for TPU‐M containing 50 wt % liquid electrolyte. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1154–1167, 2004     

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     

Potential controlled anion absorption in a novel high surface area composite of Cladophora cellulose and polypyrrole

The electrochemical properties of a novel composite paper material of high surface area consisting of polypyrrole (PPy) deposited on cellulose derived from Cladophora sp. algae have been investigated in electrolytes containing different concentrations of nitrate, chloride and p-toluene sulfonate, as well as in solutions containing both p-toluene sulfonate and chloride. The oxidation mechanism and the dependence of the oxidation behavior of the polypyrrole, which was obtained by oxidation of pyrrole with iron(III) chloride, on the anion type and concentration have been studied. Current nucleation maxima, appearing at different times depending on the anion concentration, were obtained during the oxidation of the reduced polymers as a result of the combined action of the formation and growth of conducting polymer strands and anion diffusion. No loss of capacity was seen during repeated oxidation and reduction of the polymer indicating that trapping of anions in the reduced polymer did not limit the electroactivity of the present material. The latter can be explained by the thin polymer layer present on the cellulose substrate. During the oxidation of the polymer, the anions most likely first cover most of the surface of the composite before diffusing into the bulk of the polymer. The estimated distance between these surface sites was also found to match the size of the anions. For electrolytes containing a mixture of anions, the oxidation charge depends on the concentration and size of the different anions.The combination of the thin polymer coating and the large specific surface area of the composite give rise to a high ion absorption capacity even for large anions. Hence, the investigated material should be well-suited for use in biotechnological applications involving, e.g., desalting and extraction of proteins and DNA from biological samples.     

Benign enzymatic synthesis of multiwalled carbon nanotube composites uniformly coated with polypyrrole for supercapacitors

BACKGROUND: Recently, various composites of carbon nanomaterials and conducting polymers have been actively investigated as potential electrode materials for supercapacitors which can store and deliver large amounts of electrical energy promptly. Harsh chemical or complex electrodeposition methods have been studied to prepare such composites. In this report, the mild and simple enzymatic catalysis of horseradish peroxidase (EC 1.11.1.7) in aqueous solutions (pH 4.0) was utilized for the first time to prepare composites of multiwalled carbon nanotubes and polypyrrole. RESULTS: Electron micrographs show that in situ enzymatic reaction by horseradish peroxidase enables the uniform coating of multiwalled carbon nanotubes with polypyrrole without containing the polymer aggregates. The specific capacitance of the composites (46.2 F g^?1) measured with a two‐electrode cell containing an electrolyte of 1 mol L^?1 NaNO₃ increased more than four‐fold compared with that obtained with bare multiwalled carbon nanotubes (10.8 F g^?1). CONCLUSIONS: Horseradish peroxidase‐catalyzed in situ synthesis of the composites of multiwalled carbon nanotubes and polypyrrole requires neither the derivatization of multiwalled carbon nanotubes and/or pyrrole monomers nor the post‐doping of the synthesized composites to enhance the capacitance of the composites. © 2012 Society of Chemical Industry     

Synthesis,characterizations, and physical properties of carbon nanotubes coated by conducting polypyrrole

A new type of carbon nanotube (CNT) (diameter of <100 nm) coated by conducting polypyrrole (PPY) was synthesized by in situ polymerization on CNTs. The structure of the resulting complex nanotubes (CNT‐PPY) was characterized by elemental analysis, X‐ray photoelectron spectroscopy, Raman spectra, and X‐ray diffraction. These indicated no significant chemical interaction between PPY and the CNT. The electrical, magnetic, and thermal properties of the complex nanotubes were measured and showed the physical properties of the CNTs were modified by conducting PPY. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2605–2610, 1999     

Effects of ultrasonic assisted processing and clay nanofiller on dielectric properties and lithium ion transport mechanism of poly(methyl methacrylate) based plasticized polymer electrolytes

Lithium ion conducting solid polymer electrolyte (SPE) films consisted of poly(methyl methacrylate) (PMMA) matrix with lithium perchlorate as a dopant ionic salt, poly(ethylene glycol) as plasticizer and montmorillonite clay as inorganic nanofiller have been prepared by classical solution casting and high intensity ultrasonic assisted solution casting methods. The X‐ray diffraction study confirmed the amorphous structure of all these PMMA‐based solid electrolytes and the clay nanosheets existed in exfoliated form in their amorphous phase. Dielectric relaxation spectroscopy had been employed for the investigation of complex dielectric function, ac electrical conductivity, electric modulus, and impedance spectra of these electrolytes over the frequency range from 20 Hz to 1 MHz. It was observed that the dielectric properties and ionic conductivity of the electrolytes strongly depended on the sample preparation methods, and also had changes with addition of the clay nanofiller. Temperature‐dependent dielectric study of the electrolyte films confirmed that their dc ionic conductivity and conductivity relaxation time values obeyed the Arrhenius behavior. This study also revealed that the lithium ion transportation in the ion–dipolar complexes of these electrolytes occurred through hopping mechanism and it was correlated with the conductivity relaxation time. Preparation of these electrolyte films through ultrasonic assisted solution casting method increased the ionic conductivity by more than one order of magnitude in comparison to that of the classical solution casting method, which revealed that the former was a novel method for the preparation of these SPEs of relatively enhanced ionic conductivity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42188.     

Key role of the desolvation in the achievement of the quasi-metallic state of electronically conducting polymers

Redox transformation of electronically conducting polymers was studied by different in situ combined electrochemical techniques. Results obtained with polypyrrole/dodecyl sulfate film in aqueous solution and with polythiophene/hexafluorophosphate films in acetonitrile by in situ ac conductance and EQCM support the assumption of the key role of the desolvation in the achievement of the so-called quasi-metallic state of electronically conducting polymers. The desolvation considered as a phase transition is the chemical background of the capacitive behaviour, and it causes the structural changes, which lead to a film in which the interchain interactions may form the large-scale conducting polymer matrix.     

Effect of grafting degree and side PEO chain length on the ionic conductivities of NBR-g-PEO based polymer electrolytes

Comb-shaped graft polymers were synthesized and complexed with a LiCF₃SO₃ salt to form a new class of polymer electrolytes. The polymers based on an acrylonitrile-butadiene copolymer (NBR) have pendant, short-chain poly(ethylene oxide) (PEO) grafted onto a butadiene unit. The characteristics of these polymer electrolytes were investigated in terms of number of pendant EO groups and grafting degree in the graft copolymer. The maximum conductivity was observed at the optimum side PEO chain length, and the PEO chain length for the maximum conductivity decreased with an increase in the grafting degree. And a solid ⁷Li NMR relaxation technique was used to study the local environments and dynamics of the ions in the polymer electrolytes. The maximum conductivity value obtained from our study was three orders of magnitude higher than that of classical PEO-based electrolytes at ambient temperature. These improved low temperature conducting polymers with higher relative mechanical strength are expected to be suitable for practical applications, such as in rechargeable lithium batteries or electrochromic devices.     

Poly(ethylene oxide)‐based block copolymer electrolytes for lithium metal batteries

Nanostructured block copolymer electrolytes (BCEs) based on poly(ethylene oxide) (PEO) are considered as promising candidates for solid‐state electrolytes in high energy density lithium metal batteries (LMBs). Because of their self‐assembly properties, they confer on electrolytes both high mechanical strength and sufficient ionic conductivity, which linear PEO cannot provide. Two types of PEO‐based BCEs are commonly known. There are the traditional ones, also called dual‐ion conducting BCEs, which are a mixture of block copolymer chains and lithium salts. In these systems, the cations and anions participate in the conduction, inducing a concentration polarization in the electrolyte, thus leading to poor performances of LMBs. The second family of BCEs are single‐lithium‐ion conducting BCEs (SIC‐BCEs), which consist of anions being covalently grafted to the polymer backbone, therefore involving conduction by lithium ions only. SIC‐BCEs have marked advantages over dual‐ion conducting BCEs due to a high lithium ion transference number, absence of anion concentration gradients as well as low rate of lithium dendrite growth. This review focuses on the recent developments in BCEs for applications in LMBs with particular emphasis on the physicochemical and electrochemical properties of these materials. © 2018 Society of Chemical Industry     

Immobilization of cholesterol oxidase and potassium ferricyanide on dodecylbenzene sulfonate ion‐doped polypyrrole film

Dodecylbenzene sulfonate (DBS)‐doped polypyrrole (PPY) conducting polymer films were electrochemically deposited onto the indium‐tin‐oxide (ITO)‐coated glass plates in aqueous medium. The enzyme cholesterol oxidase (ChOx) was immobilized on these DBS–PPY films by a physical adsorption technique. These ChOx‐immobilized DBS–PPY films were characterized by ultraviolet–visible and Fourier transform infrared spectroscopy. The enzyme activity studies indicate that ～40% of ChOx leaches out from the ChOx/DBS–PPY film. The ChOx activity in the ChOx/DBS–PPY film was assayed as a function of cholesterol concentration. The results of amperometric measurements conducted on ChOx/DBS–PPY/ITO film show linearity over the range 2–8 mM of cholesterol solution. The ChOx/DBS–PPY/ITO electrodes exhibit a response time of 30 s and are stable for ～3 months at 4 °C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3486–3491, 2001     

Evidence of redox interactions between polypyrrole and Fe3O4 in polypyrrole-Fe3O4 composite films

The electrical properties of conducting polymers make them useful materials in a wide number of technological applications. In the last decade, an important effect on the properties of the conducting polymer when iron oxides particles are incorporated into the conductive matrix was shown. In the present study, films of polypyrrole were synthesized in the presence of magnetite particles. The effect of the magnetite particles on the structure of the polymer matrix was determined using Raman spectroscopy. Mass variations at different concentrations of Fe₃O₄ incorporated into the conducting matrix were also measured by means of quartz crystal microbalance. Additionally, the changes in the resistance of the films were evaluated over time by electrochemical impedance spectroscopy in solid state. These results show that the magnetite incorporation decreases polymeric film resistance and Raman experiments have evidenced that the incorporation of magnetite into polymeric matrix not only stabilizes the polaronic form of the polypyrrole, but also preserves the polymer from further oxidation.     

Polymer electrolytes based on lithium sulfonate derived from perfluorovinyl ethers; single ion conductors

A new lithium perfluoroakylsulfonate has been synthesized from a commercial perfluorovinylether fitted with a fluorosulfonyl group. By making use of the vinylether group, this species was incorporated into polyurethane networks based either on a poly(ethylene oxide)glycol or on a tri‐arm star‐poly(ethylene oxide)triol. The results, in terms of ionic conductivities, thermal behaviour and different domains of rigidity (solid‐state ¹H NMR), are reported for these single cation conductor polymer electrolytes. When compared to the polymer electrolytes where the same but untethered lithium perfluoroakylsulfonate is dissolved in the same initial networks, a loss of conductivity is observed despite the higher mobility of the ionomers. This loss corresponds to the conductivity attributed to the anionic species. The higher mobility of the ionomeric electrolytes is to be related to the quasi absence of physical crosslinks. © 2000 Society of Chemical Industry     

Electromagnetic radiation shielding by composites of conducting polymers and wood

Polyaniline or polypyrrole composites with fir or oak wood have been prepared by in situ polymerization of the corresponding monomers in an aqueous suspension of wood sawdust. The percolation threshold of compressed coated particles is located below 5 wt % of the conducting component and, above this limit, the conductivity of most composites was higher than 10^?3 S cm^?1. The conductivity of composites containing ca 30 wt % of conducting polymer was of the order of 10^?1 S cm^?1, an order of magnitude lower than that of the corresponding homopolymers, polyaniline and polypyrrole. The conductivity stability has been tested at 175°C. The polypyrrole‐based composites generally lasted for a longer time than pyrrole homopolymers, also on account of the improved mechanical integrity of the samples provided by the presence of wood. The reverse order was found with polyaniline composites. The dielectric properties of the composites were determined in the range of 100 MHz–3 GHz, indicating that thick layers of composite material, ～ 100 mm, are needed for the screening of the electromagnetic radiation below ?10 dB level in this frequency range. Nevertheless, considering the potential production cost of composites and their low weight, such composite materials could be of practical interest in the shielding of electromagnetic interference. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 807–814, 2005