Electrochemical Copolymerization of Thiophene Containing Pseudo-Polyether Cages with Pyrrole (original) (raw)
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Materials Chemistry and Physics, 2006
Thiophene capped poly(ethylene oxide) (PEO) was synthesized. Copolymerisations of PEO with pyrrole (Py) and thiophene (Th) were achieved in water-sodium dodecyl sulfate (SDS) and acetonitrile (AN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couples via constant potential electrolyses. Characterisations of the samples were performed by NMR, cyclic voltammetry (CV), FT-IR, scanning electron microscopy (SEM). Electrical conductivities were measured by the four-probe technique. PEO-co-PTh film which was synthesized on ITO-glass in boron fluoride-ethyl ether (BFEE) found to exhibit electrochromic behaviour and it electrochemically switches between blue oxidized and red reduced states. Optical analyses were carried out to investigate the electronic structure of PEO-co-PTh electrochromic copolymer.
Journal of Solid State Electrochemistry, 2007
A new oligomer of N,N′-bis(2-pyrrolyl methylene)-3,4-dicyano-2,5-diaminothiophene possessing cyanosubstituted thiophene and pyrrole residues linked together by azomethine groups was used for the electrochemical polymerisation of conducting films. The approach used for the oligomer design favours inter-chain interactions through hydrogen bonding and negative charge stability through the cyano substitute thiophene. The oligomer was successfully electropolymerised at 0.67 V vs Ag + /Ag from 0.1M tetrabutylammonium tetrafluoroborate (TBABF 4 )/acetonitrile as a dark blue film on the surface of platinum electrodes. Cyclic voltammetry has been used to investigate the redox behaviour of the films. The electrically conducting polymer showed p-doping/neutralisation behaviour. The effect of different electrolytes such as TBABF 4 , tetrabutylammonium perchlorate (TBAClO 4 ), lithium perchlorate (LiClO 4 ) and sodium perchlorate (NaClO 4 ) on the redox switching and the stability of the polymer films was investigated. Infrared and UV-vis spectra of oligomer and polymers are presented. The evolution of the film growing process is shown by UV-vis spectroscopy.
Electrochimica Acta, 2003
Poly(3,4-dialkoxythiophene) films with different length of alkyl chain (1,3 and 8 carbon atoms) were obtained on Pt and ITO electrodes from the monomer solutions in acetonitrile by cyclic voltammetry (CV). The properties of the resulting films were studied by electrochemical methods, UV Á/Vis, FTIR and NMR spectra. The CVs were correlated with differential cyclic voltabsorptograms (DCVA) recorded at the absorption maxima to explain the shape of the voltammograms of the polymers studied, dependent on the alkyl-chain length in alkoxy group. The presence of the zones of different crystallinity in the polymer film was postulated. Significant influence of the type of the solvent on asymmetry of the cyclic voltammograms for the polymer doping Á/undoping has been discussed in terms of the solvent interaction with radical cation (polaron) delocalized on the alkoxy side groups. The polaron delocalization was proved by 1 H-NMR spectra. Appearance of infrared activated vibrations (IRAVs) in the range 1500 Á/600 cm (1 and a characteristic electronic band at 3300 cm (1 at the polarization potential '/0.25 V versus Ag/Ag ' and their gradual changes upon further polymer oxidation were interpreted in terms of evolution of different charge carriers in lightly and heavily doped polymer.
Synthetic Metals, 2004
A well-defined polystyrene (PSt) based polymer containing at one end-chain 3,5-dibromobenzene moiety, prepared by atom transfer radical polymerization (ATRP), was modified in two reaction steps. First one constitutes a Suzuki coupling reaction between aromatic dibromine functional polymer and 3-aminophenylboronic acid, when a diamino-containing intermediate was obtained. The second step is a condensation reaction between the diamino functional polystyrene and 2-pyrrole aldehyde. Thus, a polymer containing a conjugated sequence having pyrollyl groups at the extremities was synthesized. The presence of oxidable pyrrole groups in the structure of the polymer permitted further electropolymerization. The structures of intermediate polymers were analyzed by spectral methods ( 1 H NMR, FTIR). Electrochemical copolymerization of pyrrole functionalized polymer (PStPy) with pyrrole was carried out in acetonitrile (ACN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couple. Characterization of the resulting copolymer were performed via Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), spectroelectrochemical analysis, and kinetic study. Spectroelectrochemical analysis show that the copolymer of PStPy with Py has an electronic band gap (due to p-p* transition) of 2.4 eV at 393 nm, with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Via kinetic studies, the optical contrast %DT was found to be 20% for P(PStPy-co-Py). Results showed that the time required to reach 95% of the ultimate T was 1.7 s for the P(PStPy-co-Py). q
Polymer International - POLYM INT, 2004
Graft copolymers of poly(vinyl alcohol) with thiophene side-groups and pyrrole were synthesized by electrochemical polymerization methods. Poly(vinyl alcohol) with thiophene side-groups (PVATh) was obtained from the reaction between poly(vinyl alcohol) (PVA) and thiophene-3-acetic acid. The syntheses of copolymers of PVATh and pyrrole were achieved electrochemically by using three different supporting electrolytes, p-toluene sulfonic acid (PTSA), sodium dodecyl sulfate (SDS) and tetrabutylammonium tetrafluoroborate (TBAFB). Characterization of PVATh and graft copolymers was performed by a combination of techniques including cyclic voltammetry, scanning electron microscopy, thermal gravimetry, differential scanning calorimetry, size-exclusion chromatography, 1 HN MR and FT-IR.
Polymer International, 2005
Thiophene functionalized polystyrene samples (TFPS) were synthesized by atom transfer radical polymerization (ATRP) of styrene, followed by Suzuki coupling with 3-thiophene (Th) boronic acid. Conducting graft polymer of TFPS with thiophene was achieved at 1.5 V in tetrabutylammonium tetrafluoroborate/dichloromethane (TBAFB/DM) by electrochemical methods. Spectroelectrochemical analysis of the resulting copolymers [P(TFPS-co-Th)] reflected electronic transitions at 449, 721 and 880 nm, revealing π − π* transition, polaron and bipolaron band formation, respectively. We also successfully established the utilization of dual type complementary colored polymer electrochromic devices using P(TFPS-co-Th)/poly(3,4-ethylenedioxythiophene (PEDOT) in sandwich configuration. The switching ability, stability and optical memory of the electrochromic device were investigated by UV–visible spectrophotometry and cyclic voltammetry. Device switches between brown and blue color with a switching time of 1.3 s were prepared with optical contrast (%ΔT) of 25 %. Copyright © 2005 Society of Chemical Industry
European Polymer Journal, 2004
A well-defined polystyrene (PSt) based polymer containing at one end-chain 3,5-dibromobenzene moiety, prepared by atom transfer radical polymerization (ATRP), was modified in two reaction steps. First one constitutes a Suzuki coupling reaction between aromatic dibromine functional polymer and 3-aminophenylboronic acid, when a diamino-containing intermediate was obtained. The second step is a condensation reaction between the diamino functional polystyrene and 2-pyrrole aldehyde. Thus, a polymer containing a conjugated sequence having pyrollyl groups at the extremities was synthesized. The presence of oxidable pyrrole groups in the structure of the polymer permitted further electropolymerization. The structures of intermediate polymers were analyzed by spectral methods ( 1 H NMR, FTIR). Electrochemical copolymerization of pyrrole functionalized polymer (PStPy) with pyrrole was carried out in acetonitrile (ACN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couple. Characterization of the resulting copolymer were performed via Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), spectroelectrochemical analysis, and kinetic study. Spectroelectrochemical analysis show that the copolymer of PStPy with Py has an electronic band gap (due to p-p* transition) of 2.4 eV at 393 nm, with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Via kinetic studies, the optical contrast %DT was found to be 20% for P(PStPy-co-Py). Results showed that the time required to reach 95% of the ultimate T was 1.7 s for the P(PStPy-co-Py). q
Spectroelectrochemistry of intrinsically conducting aniline–thiophene copolymers
Electrochimica Acta, 2005
The electrochemical copolymerization between selenophene and 3-chlorothiophene monomers was successfully realized. The influence of the applied polymerization potential and the monomer feed ratio on the copolymer properties were investigated, and the results revealed that the obtained polymer films strongly depended on the polymerization conditions. The obtained copolymers showed good redox stability in acetonitrile-based electrolyte solution. Band gap energy of the homo-and copolymer films was estimated and the values were between 1.95-2.11 eV. The electrical conductivity measurements of selenophene-3-chlorothiophene copolymers were successfully achieved using a four-probe technique and generally increased with increasing temperature. Fourier transform infrared (FTIR) characterization disclosed that the bands of homopolymers were retained in the spectra of copolymers with typical assignments suggesting that α-positions in the polymer chains were involved in the polymerization.
Electrochimica Acta, 2000
3-Thiophene-acetic acid and 3-methylthiophene co-polymers have been prepared with the consideration that the solvation behaviour of the film could be modified. The modification is coupled with the observed splitting of the oxidation peak on the cyclic voltammograms. The redox transformation of the films was studied by electrochemical quartz crystal microbalance (EQCM) and in situ conductance (ISC) techniques. Mass changes during the electrochemical processes showed that the cation is not involved into the charge balancing of the film. Manifestation of self-doping was excluded by analogous measurements with an aprotic co-polymer of methylthiophene. Results completed with in situ conductance and spectroelectrochemical observations confirmed the assumption of a chemical step taking place after the first oxidation. In this process desolvation of the oxidised intermediate occurs, which is a necessary step for the achievement of the quasi-metallic state.