Towards TiO2-conducting polymer hybrid materials for lithium ion batteries

Nanocomposites of TiO₂ (anatase) with polypyrrole (Ppy) or poly(3,4-ethylenedioxythiophene) (PEDOT) were prepared via electrochemical routes. The deposition process of the conducting polymer films was performed in the presence of perchlorate, p-toluenesulphonate (TOS) or bis(trifluoromethylsulphonyl)imide (TFSI) anions in propylene carbonate (PC). The obtained electrode materials were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). An improvement of lithium ion intercalation/de-intercalation properties of titanium(IV) oxide as a result of its interfacing with the polymers is evidenced. This effect was strongly dependent on the thickness of the polymer layer and closely related to the polymer facility for transporting of lithium ion. Polypyrrole properties, in contrast to the PEDOT case, are very sensitive to selection of the substrate material (Pt or Pt/TiO₂) during electropolymerization. Polypyrrole deposited on a rough surface exhibits an improvement in its ion exchange abilities. The impact of underlying TiO₂ layers on Ppy properties has an indirect (synergic) influence on the effectiveness of lithium ion intercalation into the oxide too. The properties of the composites were discussed also in view of the comparative electrochemical quartz crystal microbalance (EQCM) study focussing on ion transport properties of Ppy and PEDOT.     

聚合物发光电化学池研究进展

共轭聚合物是一类结合了光学、半导体电子性能和聚合物加工性能的新型材料,1995年聚合物发光电化学池出现以来就引起了广泛关注,文章在对文献结果分析的基础上总结了影响聚合物发光电化学池性能的若干因素和最新的研究进展。     

Electroactive polymer blends

The rapid development of two new classes of electrically active polymer materials, electronically conducting and electroactive polymers and ion-conducting polymers respectively, offers new possibilities for application of both classes of material, especially in combination with each other. While some of these combinations have been attempted before, they all met serious problems due to poor interpenetration of the two polymers. The recent availability of solubilized and soluble electroactive and conductive polymers has greatly advanced the possibilities of reducing the interpenetration problem. Some experimental studies using the combination of solubilized electroactive polypyrrole with poly(ethylene oxide) in an electroactive polymer blend electrode for solid-state polymer batteries are discussed. The opportunities for using polymer blends for solid-state electrochemical polymeric devices, and avenues for the development of materials for such devices, are also reviewed.     

Resistance of the Polypyrrole/Polyimide Composite by Electrochemical Impedance Spectroscopy

Electrically conducting polymers are promising for applications in polymer based charge storage devices and for membrane applications. Composing polypyrrole with polyimide improves mechanical properties of polypyrrole and affects the electrochemical properties of the composite. In this paper resistance to ion flow of pure polyimide and of the polypyrrole/polyimide composite were studied by electrochemical impedance spectroscopy, comparatively, as a function of applied potentials and of amount of polypyrrole. Electron scanning microscopy and surface mapping were used for surface characterization. Observed behavior was explained with electroactivity of the components of the composite. Conclusions about the effect of polypyrrole on the structure and resistance were made.     

Molecularly imprinted polypyrrole prepared by electrodeposition for the selective recognition of tryptophan enantiomers

Herein we report the electrosynthesis of polypyrrole with L ‐tryptophan (L ‐Trp) as a template to prepare molecularly imprinted polymers (MIPs). Overoxidized polypyrrole films with cavities complementary to the template were used for the enantioselective detection of L ‐Trp and D ‐tryptophan (D ‐Trp). Important parameters, such as the electropolymerization potential, overoxidization potential and time, thickness of the polypyrrole films, and scanning rate of the stripping voltammetric experiments, were varied to achieve an optimum sensor response. We found that L ‐Trp was inserted about 2 times higher into the imprinted polymer film than D ‐Trp. Also, in this study, an electrochemical quartz crystal microbalance technique was used to investigate the performance of overoxidized polypyrrole films. The enantioselectivity of the MIPs was attributed to the cavities in the imprinted films, which were complementary to the target molecules, both in shape and in positioning of the functional groups. The results also suggest the feasibility of preparing MIPs by electropolymerization for the enantioselective recognition of other amino acid enantiomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Review study of electrochemical impedance spectroscopy and equivalent electrical circuits of conducting polymers on carbon surfaces

Electrochemical impedance spectroscopy (EIS) is an experimental method for characterizing electrochemical systems. This method measures the impedance of the concerned electrochemical system over a range of frequencies, and therefore the frequency response of the system is determined, including the energy storage and dissipation properties. The aim of this article is to review articles focusing on electrochemical impedance spectroscopic studies and equivalent electrical circuits of conducting polymers, such as polypyrrole, polycarbazole, polyaniline, polythiophene and their derivatives, on carbon surfaces. First, the conducting polymers are introduced. Second, the electrochemical impedance spectroscopic method is explained. Third, the results of EIS applications using equivalent electrical circuits for conducting polymers taken from the literature are reviewed.     

Conducting polymers are not just conducting: a perspective for emerging technology

Conducting polymers, such as polyaniline and polypyrrole, are organic semiconductors with mixed electronic and ionic conductivity. In addition to electrical properties, their electrochemical activity opens research opportunities in corrosion protection or energy‐storage devices. Conducting polymers are active in catalysis, the photocatalytic decomposition of dyes or electrocatalysts in fuel cells being examples. In contrast to classical polymers, conducting polymers respond to various stimuli by changes in conductivity, colour or other physicochemical parameters; this is used in sensors. Conducting polymers are good adsorbents of organic pollutants in wastewater treatment and are likely to be applicable for environmental issues. The perspectives of these polymers are briefly outlined. © 2019 Society of Chemical Industry     

Piezoelectric properties of PVDF-conjugated polymer nanofibers

This study presents the development and characterization of PVDF-conjugated polymer nanofiber-based systems. Five different conducting polymers (CPs) were synthesized successfully and used to create the nanofiber systems. The CPs used are polyaniline (PANI), polypyrrole (PPY), polyindole (PIN), polyanthranilic acid (PANA), and polycarbazole (PCZ). Nanofiber systems were produced utilizing the Forcespinning® technique. The nanofiber systems were developed by mechanical stretching. No electrical field or post-process poling was used in the nanofiber systems. The morphology, structure, electrochemical and piezoelectric performance was characterized. All of the nanofiber PVDF/CP systems displayed higher piezoelectric performance than the fine fiber PVDF systems. The PVDF/PPY nanofiber system displays the highest piezoelectric performance of 15.56 V. The piezoelectric performance of the PVDF/CP nanofiber systems favors potential for an attractive source of energy where highly flexible membranes could be used in power actuators, sensors and portable, and wireless devices to mention some.     

聚吡咯纳米复合材料制备及应用研究进展

在导电聚合物中掺杂纳米粒子复合改性是提高其性能的有效途径之一。文中综述了目前聚吡咯纳米复合材料的制备方法,包括电化学聚合法、化学氧化法、模板法、溶胶-凝胶法以及制备纳米纤维常用的静电纺丝法;根据其优异的导电性和化学特性,阐述了近年来聚吡咯纳米复合材料在传感器、生物医学、电子器件、棉织物、吸附除杂以及腐蚀保护领域的应用现状;此外,指出提高对复合材料表征手段的准确性以及共混时的分散性都是明确液相转化成固相过程机理时需要解决的问题,同时控制界面的相关参数并提高界面化学参数的测试手段,建立相关模型,实现微观与宏观的融合,是提高纳米复合材料性能的关键,也是未来研究的重要方向。     

Polymers of phenylenediamines

The chemical or electrochemical oxidation of phenylenediamines in acidic aqueous media yields the corresponding oligomers or polymers. Their structures and properties are discussed in relation to a closely-related conducting polymer, polyaniline. Depending on the reaction conditions, polyphenylenediamines are produced as powders, colloidal dispersions, thin films, or composites. In contrast to polyaniline, polyphenylenediamines are rated as non-conductors and their conductivities are low. Similarly to polyaniline, these polymers display a salt–base transition and they are redox-active. They act as reductants of noble-metal compounds to the corresponding metals or as precursors in the carbonization to nitrogen-rich carbons. Applications proposed in the literature are outlined; they include the corrosion protection of metals, catalysis, electrorheology, sensors, energy-conversion devices, electrochromism, noble-metal recovery, and water treatment.     

Sensitivity enhancement for microbial biosensors through cell Self-Coating with polypyrrole

Abstract

The development of amperometric glucose biosensors based on Aspergillus niger is an established method as is the use of conducting polymers (CPs) for improvement of analytical features. The novelty proposed herein consists in the synthesis of polypyrrole (Ppy) in situ, within the cellular membrane/wall for enhancement of electrochemical features of the cells in the context of electroanalytical applications. The process accomplishes a two-fold purpose: (i) it makes use of biocatalysts yielded by the cells without need for enzyme separation and purification; (ii) it involves cellular components, which perform self-coating with Ppy without need for chemical functionalization.     

The role of ion and solvent transport during the redox process of conducting polymers

The understanding of the redox behavior of conducting polymers is essential for a successful application of these so-called synthetic metals as functional coatings. The redox process involves the exchange of ions and solvent molecules. This so called doping/dedoping process involves changes of the mechanical and the electronic structure of the polymer. This paper discusses investigations at poly(3,4-ethylenedioxythiophene (PEDOT) and poly(pyrrole) (Ppy) by the electrochemical quartz crystal microbalance (EQCM) technique and electrochemical impedance spectroscopy (EIS). In the case of PEDOT a determination of the anion and the solvent fluxes was possible, and it was found that most anions replace solvent molecules upon their incorporation. The doping/dedoping mechanism of Ppy is more complicated. Here, the first redox cycles are characterized by a complex interplay of cation, anion and solvent fluxes with irreversible changes of the polymer structure. However, in combination with EIS new insights of the ion and solvent exchange and its influence on the electronic properties can be achieved.     

Borylated Polyolefins and their Applications

Different preparative routes for the attachment of organoboron moieties to polyolefins and applications of such materials are reviewed. Preparation from boron-functionalized monomers represents one possible synthetic strategy with free radical polymerization, Ziegler–Natta polymerization, and ring-opening metathesis polymerization methods as the most thoroughly studied procedures. Recent advances in the preparation of boron-containing polymers through polymer modification reactions provide an interesting alternative that allows for the facile preparation of well-defined organoboron polymers of various architectures including homo polymers, random copolymers, block copolymers, and telechelic polymers. New opportunities for organoboron polymers as supported catalysts, sensors, luminescent materials, device components, and precursors to ceramics are briefly discussed.     

Promoting effect of electroactive polymer supports on the catalytic performances of palladium-based catalysts for nitrite reduction in water

Conducting polymers, polypyrrole and polyaniline, were used as supports for Pd in order to obtain catalysts with higher performances than a classical Pd/Al₂O₃ catalyst for application in water treatment. The supports and the catalysts were characterized by elemental analysis, Fourier transformed infra-red spectroscopy (FTIR), transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD) and by their activity in nitrite reduction. It was demonstrated that these conducting polymers can be advantageously used as support for noble metals such as palladium. Indeed, the redox properties of these supports allow the deposition of a part of palladium directly in the reduced state and also a direct reduction of nitrite, even if this reduction is not complete. The Pd/polyaniline and Pd/polypyrrole catalysts are much more active than the classical Pd/Al₂O₃ catalyst with less ammonium ions. These better performances were explained by the redox and ion-exchange properties of the conducting polymers allowing the exchange between the hydroxides produced and the dopant anion of the conducting polymer. The ion-exchange property of the polymer depends on its oxidation state which is directly linked to the polymerization conditions and then can be easily modulated.     

Conducting Polymer Nanostructures and their Derivatives for Flexible Supercapacitors

This review provides a brief summary of the recent research developments in the fabrication and application of conducting polymer nanostructures and their derivatives as electrodes for flexible supercapacitors (SCs). By controlling the nucleation and growth process of polymerization, conducting polymers (CPs) with different nanostructures can be prepared by employing chemical polymerization, electrochemical polymerization and photo-induced polymerization. These CPs (such as polyaniline and polypyrrole) with special nanostructures possess high capacitance, superior rate capability ascribed to large electrochemical surface, and optimal ion diffusion path in the ordered nanostructures. The composites of nano-structured conducting polymer and some conductive flexible substrates (such as carbon nanotube film and graphene film) are proved to be ideal electrode materials for high performance flexible SCs. Furthermore, high N-containing CPs are very prospective for preparing N-doped carbon materials used as flexible electrodes for flexible SCs. With respect to the extra pseudo-capacitance induced by N atoms and superior stability derived from the conjugated graphitic structure of carbon materials, the obtained flexible SCs based on N-doped carbon materials could achieve high capacitance, high rate performance, and superior cycling stability.     

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.     

Influence of Process Parameters on the Conductivity and Surface Morphology of Polypyrrole Films

Influence of electrochemical process parameters such as monomer and electrolyte concentrations, current density, pH of the electrolyte, and type of electrolyte have been studied during polymerization of polypyrrole (Ppy). The changes in the conductivity of synthesized Ppy film for different electrolytes were observed by chronopotentiograms recorded during the electrochemical polymerization and it was confirmed by measuring it using four probe techniques. It was found that the electrochemical process parameters have a considerable influence on the conductivity of the film. The Ppy film was synthesized on a platinum substrate by electrochemical polymerization with different electrolytes such as potassium nitrate, sodium nitrate, sulphuric acid, hydrochloric acid, potassium chloride, sodium chloride, oxalic acid, and sodium salicylate, under galvanostatic condition over a wide range of pH of the reaction medium and applied current density. The different concentration ratios of pyrrole and sodium nitrate were considered during synthesis of Ppy films. It has been observed that the polymerization potential increases with the pH and applied current density. One could synthesize Ppy film with very good surface morphology and conductivity with optimized process parameters. The characterization of synthesized Ppy film was done by electrochemical technique, electrical conductivity, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM).     

Trends in Conducting Polymer and Hybrids of Conducting Polymer/Carbon Nanotube: A Review

Several conducting polymers, including polyaniline, polypyrrole, polythiophene, polyvinylpyrrolidone, poly(3,4-ethylenedioxythiophene), poly(m-phenylenediamine), polynaphthylamine, poly(p-phenylene sulfide), and their carbon nanotube reinforced nanocomposites are discussed in this review. The physical, electrical, structural and thermal properties of polymers along with synthesis methods are discussed. A concise note on carbon nanotubes regarding their purification, functionalization, properties and production are reported. Moreover, the article focuses upon synthesis methods, properties and applications of conducting polymer/carbon nanotube nanocomposites are focused. Nanotube dispersion, loading concentration and alignment within conducting polymer/carbon nanotube nanocomposite affect their performance and morphology. The conducting polymer/carbon nanotube nanocomposites are substantially used in sensors, energy storage devices, supercapacitors, solar cells, EMI materials, diodes, and coatings.     

Electrochemical stability of PEDOT for wearable on-skin application

Conducting polymers are promising candidates for wearable devices due to mechanical flexibility combined with electroactivity. While electrochemical measurements have been adopted as a central transduction method in many on-skin sensors, less studied is the stability of the active materials (in particular poly3,4-ethylenedioxythiophene, PEDOT) in such systems, particularly for “on-skin” applications. In this study, several different variants of doped PEDOT are fabricated and characterized in terms of their (electrical, physical, and chemical) stability in biological fluid. PEDOT doped with tosylate (TOS) or polystyrenesulfonate (PSS) are selected as prototypical forms of conducting polymers. These are compared with a new variant of PEDOT co-doped with both TOS and PSS. Artificial interstitial fluid (aISF) loaded with 1% wt/vol bovine serum albumin is adopted as the testing medium to demonstrate the stability in dermal applications (i.e., conducting polymer microneedles or coatings on microneedles). A range of techniques such as cyclic voltammetry and electrochemical impedance spectroscopy are used to qualify and quantify the stability of the doped conducting polymers. Furthermore, this study is extended by using human skin lysate in the aISF to demonstrate proof-of-concept for stable use of PEDOT in wearable “on-skin” electronics.     

Electrochemical synthesis of polypyrrole in ionic liquids

Electrochemical synthesis of inherently conducting polymers such as polypyrrole is traditionally performed in a molecular solvent/electrolyte system such acetonitrile/lithium perchlorate. We report the use of ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide and N,N-butylmethylpyrrolidinium bis(trifluoromethanesulfonyl) amide, both as the growth medium and as an electrolyte for the electrochemical cycling of polypyrrole films. Use of the ionic liquid as the growth medium results in significantly altered film morphologies and improved electrochemical activities.