Screen-printed poly(3,4-ethylenedioxythiophene) (PEDOT): A new electrochemical mediator for acetylcholinesterase-based biosensors

This work describes the use of a PEDOT:PSS-based conductive polymer for designing AChE-based biosensors. The transducers were obtained directly by screen-printing a PEDOT:PSS suspension on the surface of thick film carbon electrodes. The obtained working electrodes showed a high conductivity when compared with electrodes modified with conventional mediators like cobalt phthalocyanine or tetracyanoquinodimethane. The PEDOT:PSS polymer was shown to be suitable for thiocholine oxidation, allowing the measurement of AChE activity at 100 mV vs Ag/AgCl. The high conductivity of PEDOT:PSS allowed the accurate detection of the organophosphate insecticide chlorpyrifos-oxon at concentrations as low as 4 × 10⁻⁹ M, corresponding to an inhibition ratio of 5%.     

A UV-Visible/Raman spectroelectrochemical study of the stability of poly(3,4-ethylendioxythiophene) films

Poly(3,4-ethylendioxythiophene) films were electropolymerized in aqueous medium without using any surfactant, on glassy carbon electrodes. UV/Vis and Raman spectroelectrochemical techniques were used to analyze the degradation of the polymer film occurring at different pH values. Spectroelectrochemistry has proven to be a very useful analytical tool for this purpose, thanks to its ability to provide information not only about the extent of degradation, but also about mechanistic aspects of the process. From our results we extracted important information about the main factors that play a role in the degradation, in particular about the influence of repetitive doping and de-doping cycles and of photo-induced processes, as a function of the characteristics of the solution, i.e. of pH.     

Efficient post-polymerization functionalization of conducting poly(3,4-ethylenedioxythiophene) (PEDOT) via ‘click’-reaction

The possibility to functionalize polymers after a successful polymerization process is often an important challenge in macromolecular science. Herein, modified electrodes based on azide-containing potentiodynamically electropolymerized PEDOT derivatives are reported. This reactive coatings are subsequently modified under mild heterogeneous conditions by copper-catalyzed Huisgen 1,3-dipolar cycloaddition with terminal alkynes, the so-called ‘click’-reaction. A series of terminal alkynes have been successfully used for the facile immobilization of neutral, electron-accepting and electron-donating units to the conducting PEDOT with high conversion efficiencies showing the broad scope of the strategy. The route is devoid of the limitations generated by the various steric and electronic impacts of the substituents when attached to the monomer before polymerization.     

Synthesis and microwave absorbing properties of poly(3,4‐ethylenedioxythiophene) (PEDOT) microspheres

Poly(3,4‐ethylenedioxythiophene) (PEDOT) solid and hollow microspheres were successfully synthesized by simply adjusting the concentration of 3,4‐ethylenedioxythiophene (EDOT) and the molar ratio of EDOT to ammonium persulfate (APS) (represented by (EDOT)/(APS)), respectively. Microwave absorbing properties of PEDOT microspheres with tunable reflection loss (RL) and microwave frequency band were described in detail. The relationships between the conductivity and RL of PEDOT microspheres were also discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Click-functionalization of conducting poly(3,4-ethylenedioxythiophene) (PEDOT)

Efficient post-functionalization of conductive polymer films was achieved by Cu(+)-catalyzed "click"-cycloaddition of novel poly(azidomethyl-EDOT) and various functionalized terminal alkynes under mild heterogeneous conditions with high conversion efficiencies.     

ESR spectroelectrochemistry of poly(3,4-ethylenedioxythiophene) (PEDOT)

In situ ESR spectroelectrochemical studies of poly(3,4-ethylenedioxythiophene) (PEDOT) have been performed, in an attempt to take a closer look at species responsible for the conductivity of the polymer in the doped state. A series of ESR spectra at progressively changed potentials applied to the polymer film in the oxidation and subsequently, reduction half-cycles were recorded. The results reveal distinct ESR lines with a noteworthy concentration of spins in the reduced state of the polymer and marked changes in both the intensities and ΔB_pp widths of the ESR signal across the studied potential range, indicating non-trivial changes in the character of charge carriers with changing potential. Also, interesting phenomena like the potential hysteresis of the spin concentration and of ΔB_pp linewidths between the oxidation and reduction cycles of the polymer are observed. The presence of residual spins in the polymer in the reduced state may indicate that at least to some partial extent, PEDOT chains exist in the quinoid rather than benzoid configuration in the dedoped state. Hysteresis of spectroscopic parameters may imply that certain hindrance factors like slow anion expulsion speed accompany the dedoping process of the polymer.     

Synthesis of calibrated poly(3,4-ethylenedioxythiophene) latexes in aqueous dispersant media

The synthesis of spherical poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles with a narrow size distribution was achieved in a dispersant aqueous medium. Various oxidants such as ammonium persulfate, iron(III) p-toluenesulfonate, and iron(III) trichloride were tested. A series of end-functionalized poly(ethylene oxide) (PEO) such as alpha-(3,4-ethylenedioxythiophene) PEO, alpha-( N-methyl pyrrole) PEO, alpha-(fluorene) PEO, alpha,omega-( N-methyl pyrrole) PEO, alpha,omega-(thiophene) PEO, and alpha,omega-(fluorene) PEO were compared as reactive stabilizers. The molar mass and the functionality of these reactive PEOs were found to be important parameters with respect to the control of particle size and size distribution. PEDOT samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), size exclusion chromatography (SEC), and conductivity measurements.     

Ritter Reactions between Alcohols and Acetonitrile Mediated by the Conducting Polymer Poly-(3,4-ethylenedioxy Thiophene) (PEDOT)

Herein, we report new reactivity of the conducting polymer, poly-(3,4-ethylenedioxy thiophene) (PEDOT), where PEDOT mediates a Ritter reaction between alcohols and acetonitrile. The yields were variable and in most cases competitive with results obtained using sulfuric acid. Attempts at a stoichiometric reaction between benzonitrile and diphenylmethanol are also reported herein. Finally, described here are preliminary mechanistic studies that suggest PEDOT is behaving as an alcohol-selective or specific Lewis acid.

Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for full experimental and spectral details.     

The Simplest Model for Doped Poly(3,4-ethylenedioxythiophene) (PEDOT): Single-crystalline EDOT Dimer Radical Cation Salts

Although doped poly(3,4-ethylenedioxythiophene) (PEDOT) is extensively used in electronic devices, their molecular-weight distributions and inadequately defined structures have hindered the elucidation of their underlying conduction mechanism. In this study, we introduce the simplest discrete oligomer models: EDOT dimer radical cation salts. Single-crystal structural analyses revealed their one-dimensional (1D) columnar structures, in which the donors were uniformly stacked. Band calculations identified 1D metallic band structures with a strong intracolumnar orbital interaction (band width W≈1 eV), implying the origin of the high conductivity of doped PEDOT. Interestingly, the salts exhibited semiconducting behavior reminiscent of genuine Mott states as a result of electron–electron repulsion (U) dominant over W. This study realized basic models with tunable W and U to understand the conduction mechanism of doped PEDOT through structural modification in oligomers, including the conjugation length.     

A platform to synthesize a soluble poly(3,4‐ethylenedioxythiophene) analogue

Alkyl‐substituted polyhedral oligomeric silsesquioxane (POSS) cage is combined with 3,4‐ethylenedioxythiophene under the same roof. The corresponding monomer called EDOT‐POSS is used to get soluble poly(3,4‐ethylenedioxythiophene) (PEDOT‐POSS) analogue. Both chemically and electrochemically obtained polymers are soluble in common organic solvents like dichloromethane, chloroform, tetrahydrofuran, and so forth. The PEDOT‐POSS has somewhat higher band gap (1.71 eV at 618 nm) than its parent PEDOT (1.60 eV at 627 nm) and as expected the PEDOT‐POSS exhibits higher optical contrast (74% at 618 nm) and coloration efficiency (582 cm²/C for 100% switching), lower switching time (0.9 s), higher electrochemical stability (93% of its electroactivity retains after 5000 cycles under ambient conditions) when compared to the PEDOT. A number of advantages of the PEDOT‐POSS over the PEDOT can make it a promising material in the areas of electro‐optical applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3935–3941     

Preparation of poly(3,4-ethylenedioxythiophene)(PEDOT) coated silica core-shell particles and PEDOT hollow particles

Nanometre-sized PEDOT-silica core-shell particles were synthesized and self-assembled into crystalline colloidal arrays with a reflection peak in the visible region; these particles were also etched with hydrofluoric acid to produce hollow PEDOT particles.     

Synthesis and characterization of p-toluenesulfonate incorporated poly(3,4-ethylenedioxythiophene)

Poly(3,4-ethylenedioxythiophene) (PEDOT), a conducting polymer, was electrochemically synthesized with p-toluenesulfonate (TSNa) as a dopant on gold surface. The electrochemical properties of the polymer were studied by impedance spectroscopy and cyclic voltammetry (CV). It was found that the impedance magnitude of the electrode significantly decreased over a wide range of frequency from 10⁰ to 10⁴ Hz after the polymer deposition. The CV demonstrated enhanced reversibility of the PEDOT film. The surface morphology was investigated by scanning electronic microscope (SEM) and atomic force microscope (AFM). Due to the effect of TSNa structure, nano-fungus was observed. Polymerization time was optimized and 30 min deposition resulted in the highest charge capacity, showing the highest electroactive surface area, possibly due to its porous structured polymer. Moreover, the high specific surface area could be favorable for cell attachment. The stability of PEDOT in glutathione (GSH), a common biologically relevant reducing agent, was studied with polypyrrole (PPy) as a baseline. It showed that the former had much better stability than the latter and it could be an excellent candidate for potential applications of in vivo neural devices.     

Synthesis and characterisation of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) Zr(IV) monothiophosphate composite cation exchanger: analytical application in the selective separation of lead metal ions

In this study, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) zirconium(IV) monothiophosphate composite cation exchanger was prepared by sol–gel precipitation method. The presence of sulphur in the cation exchanger enhances affinity towards the heavy metal ions which can improve the selectivity of the material. The selectivity studies showed that the material is selective towards Pb(II) ions. To characterise the material, several physicochemical properties were also studied which includes X-ray, scanning electron microscopy and transmission electron microscopy studies. The ion-exchange behaviour of this cation exchanger was studied by using some of the selected properties like ion-exhange capacity for various metal ions, elution, effect of eluent concentration, thermal effect on ion-exchange capacity (IEC). The results of IEC and physicochemical properties revealed that the material is nanocomposite, crystalline, chemically, mechanically and thermally stable. The analytical ability of this cation exchanger was demonstrated in binary separation of Pb(II) ions from a mixture of other metal ions. The recovery is qualitative and the separations are reproducible.     

"Click"-modification of a functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) soluble in organic solvents

A PEDOT-based conductive copolymer soluble in organic solvents was synthesized electrochemically using dihexyl-EDOT and azidomethyl-EDOT as monomers and was successfully post-functionalized by "click"-cycloaddition reaction with a functionalized terminal alkyne under mild heterogeneous conditions.     

Synthesis and characterisation of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) Zr(IV) monothiophosphate composite cation exchanger: analytical application as lead ion selective membrane electrode

A Pb²⁺ ion selective membrane electrode based on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) Zr(IV) monothiophosphate composite cation exchange material was fabricated using solution casting method. The effect of membrane composition on the proton exchange capacity was investigated by using varying amounts of electroactive material. The membrane with 250 mg of electroactive material and 10 µL of plasticiser exhibited higher proton conductivity. The optimised membrane composition was used for the fabrication of ion selective membrane electrode which exhibited typical Nernstian response towards Pb²⁺ ions in the concentration range 20.70 gL^?1–20.7 µgL^?1 (1 × 10^–1–1 × 10^–7 mol L^?1) with a sub-Nernstian slope of 27.429 mV per decade change in Pb²⁺ ion concentration. The response time of the electrode under study for Pb²⁺ ions was found to be 11 s and the electrode can be used for 120 days without any considerable divergence in response potential. It can also be successfully used in the pH range from 3.0 to 6.5. It was found selective for Pb²⁺ ions in the presence of various monovalent, divalent and trivalent interfering metal ions. It was also employed as an indicator electrode in the potentiometric titration of Pb²⁺ ions using ethylenediaminetetraacetic acid, disodium salt, as a titrant.     

Characterization of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) adsorption on cellulosic materials

The interaction between poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) and cellulosic fibers was characterized in order to obtain further understanding of the conductivity properties of the modified cellulosic fiber material. Microcrystalline cellulose (MCC) was used as a model surface to study the adsorption behavior at various pH and salt concentrations, while samples of low-conductivity paper, normally used for the production of electrical insulation papers, were dipped into PEDOT:PSS dispersion and air-dried for X-ray photoelectron spectroscopy (XPS) studies. The results showed a strong interaction between the MCC and PEDOT:PSS, which implied a broad molecular distribution of the conducting polymer. With increasing pH, less amount of the conducting polymer was adsorbed whereas the amount adsorbed passed through a maximum value with varying salt concentration. Zeta potential measurement and polyelectrolyte titration were used to determine the surface charge of both suspended MCC particles and dispersed PEDOT:PSS at various pH levels and salt concentrations. Dip-coated paper samples exhibited two peaks in the S(2p) XPS spectra at 168–169 and 164–165 eV which correspond to the sulfur signals of sulfonate (in PSS) and in thiophene (in PEDOT), respectively. It was found that the PEDOT:PSS with a ratio of 1:2.5 was adsorbed more in the base paper than that with a ratio of 1:6. The PEDOT:PSS ratio on the surface of the cellulosic material was higher than that in the bulk liquid for all samples. The results indicated that PEDOT was preferentially adsorbed rather than PSS. The degree of washing of the conducting polymer did not significantly affect the PEDOT enhancement on the surface.     

Investigation of charge carriers in poly(3,4-butylenedioxythiophene) (PBuDOT) by means of ESR spectroelectrochemistry

In situ ESR spectroelectrochemical studies of poly(3,4-butylenedioxythiophene) (PBuDOT) have been performed, in order to investigate more closely the species responsible for the conductivity of this polymer in the doped state. In the process of electrochemical doping of the polymer, ESR spectra at progressively changed potentials were recorded. Then the subsequent dedoping process was studied accordingly. The results reveal that PBuDOTs ESR spectroscopic properties are markedly different form its close relative, poly(3,4-etylenedioxythiophene) (PEDOT). Firstly, the potential dependence of the spin concentration displays a clear peak-shaped transient with a gradual decrease at higher oxidation potentials. Similar behaviour is seen for the B_pp widths of the ESR signal, indicating that the type of interactions between paramagnetic centres is potential sensitive. The course of the reduction process of the polymer is more or less the reverse of the oxidation one, with only a slight hysteresis of the spin concentration and a barely discernible one of B_pp widths being observed. In PBuDOT, as in PEDOT, distinct narrow ESR lines revealing a noteworthy spin concentration in the reduced state of the polymer have also been observed. The presence of these residual spins in the dedoped polymer may indicate that the dedoping process of this polymer is indeed a slow one. The presence of trace amounts of impurities or oxygen may hinder the dedoping process, especially for thicker films.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003)     

Investigation of the doping efficiency of poly(styrene sulfonic acid) in poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonic acid) dispersions by capillary electrophoresis

CE can efficiently separate poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) complexes and free PSS in dispersions and can be used to estimate the degree of PSS doping. We investigated the doping efficiency of PSS on PEDOT in dispersions using CE and its effect on the conductivity of the resulting PEDOT/PSS films. Results of this study indicate that dispersions containing 1:2.5–3 EDOT:PSS feed ratio (by weight) exhibiting 72–73% PSS doping generate highly processable and highly conductive films. Conductivity can be optimized by limiting the time of reaction to 12 h. At this point of the reaction, the PEDOT/PSS segments, appearing as broad band in the electropherogram, could still exist in an extended coil conformation favoring charge transport resulting in high conductivity. Above a threshold PEDOT length formed at reaction times longer than 12 h, the PEDOT/PSS complex, appearing as spikes in the electropherogram, most likely have undergone a conformational change to coiled core‐shell structure restricting charge transport resulting in low conductivity. The optimal conductivity (5.2 S/cm) of films from dispersions synthesized for 12 h is significantly higher than those from its commercial equivalent Clevios P and other reported values obtained under similar conditions without the addition of codopants.     

Interpolymer complexation in hydrolysed poly(styrene-co-maleic anhydride)/poly(styrene-co-4-vinylpyridine)

Complexation between hydrolysed poly(styrene-co-maleic anhydride) (HSMA) copolymers containing 28% and 50% maleic anhydride and a poly(styrene-co-4-vinylpyridine), St4VP32 copolymer with 32% of 4-vinylpyridine content has been investigated. Formation of interpolymer complexes from 1,4-dioxane solutions is observed, over the entire composition range and the stoichiometry of these complexes has been determined from elemental analysis.Quantitative FTIR study of the system HSMA50/StV4Py32 shows that the ideal complex composition leads to 2:1 unit mole ratio of interacting component. FTIR results are in good agreement with DSC and TGA ones, since this complex composition gives the maximum value of the glass transition temperature and the best thermic stability.For the systems investigated, the T_g versus composition curve do not follow any of the commonly accepted models proposed for polymer blends. A new model proposed by Cowie [Cowie JMG, Garay MT, Lath D, McEwen IJ. Br Poly J 1989;21:81] is used to fit the T_g data and found to reproduce the experimental results more closely.     

Novel flexible chemical gas sensor based on poly(3,4-ethylenedioxythiophene) nanotube membrane

Poly(3,4-ethylenedioxythiophene) nanotubes (PEDOT NTs) flexible membrane was successfully fabricated by vapor deposition polymerization (VDP) mediated electrospinning for ammonia gas detection. PVA nanofibers (NFs) were electrospun as a core part and polyvinyl alcohol (PVA)/PEDOT coaxial nanocables (NCs) were prepared by VDP method via EDOT monomer adsorption onto the electrospun PVA NFs as templates. To obtain the PEDOT NTs membrane, the PVA NFs were removed from PVA/PEDOT coaxial NCs with distilled water. PVA/PEDOT coaxial NCs and PEDOT NTs had the conductivities of 71 and 61 S cm⁻¹ and were applied as a transducer for ammonia gas detection in the range of 1-100 parts per million (ppm) of NH₃ gas. They exhibited the minimum detectable level of ca. 5 parts per million (ppm) and fast response time (less than 1 s) towards ammonia gas. In a recovery time, the PEDOT NTs membrane sensor was ca. 30 s and shorter compared to that of the membrane sensor based on the PVA/PEDOT NCs (ca. 50 s). In addition, sensor performance of PEDOT NTs membrane was also undertaken as a function of membrane thickness. Thick membrane sensor (30 μm) had the enhanced sensitivity and the sensitivity on the membrane thickness was in the order of 30 μm > 20 μm > 10 μm at 60 ppm of NH₃ gas.