A spectroelectrochemical study of poly(dithienothiophenes) (original) (raw)
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Synthetic Metals, 2004
Three novel 3-[-(p-methoxyphenoxy)alkyl]thiophene monomers were synthesized and electrochemically polymerized on ITO electrodes by potentiodynamic or potentiostatic methods. Potentiostatic deposition provided films with better stabilities and had smaller quantities of soluble oligomers formed during polymerization. We also observed that derivatives with shorter alkyl chains in the substituted thiophene are difficult to polymerize by electrochemical methods. Spectroelectrochemical characterization of the polymer films obtained showed that their colors depend on the alkyl chain length in the substituted monomer. This demonstrates that the electrochromic behavior of these polymers can be tailored by means of the chemical synthesis of the monomers. The electrochromic properties presented by these new polymers motivate their future application in electrochromic devices.
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. #
Electrochemical Polymerization and Characterization of 2-Vinylthiophene and Some of Its Derivatives
Macromolecules, 1994
We have polymerized 2-vinylthiophene (2-VTh) anodically at a potential of 2.75 V vs Ag/Ag+ in acetonitrile solvent using tetrabutylammonium tetrafluoroborate as supporting electrolyte. Two products result: a semiconducting (10-4 S/cm), dark coating on the electrode (polymer C) and a nonconducting precipitate from the anolyte solution (polymer B). Polymer B is spectroscopically similar to poly(2-vinylthiophene) (PVTh) produced by bulk, benzoyl peroxide-initiated polymerization of 2-VTh (polymer A) except that it has a lower molecular weight (1.5 X lo3 vs 1.9 X 104 for polymer A by SEC using polystyrene as standard).
The electrochemical polymerisation of 3-hydroxymethyl-2,2 :5 ,2-terthiophene, afforded a new conducting polymer bearing the nucleophilic –CH 2 OH substituent in-position. The characteristics of the system obtained have been defined through electrochemical and spectroelectrochemical techniques, as a function of the nature of the solvent in which polymerisation has been carried out and in which polymer doping is electrochemically induced. Two different morphological and/or structural fractions are obtained when the polymer is electrogenerated in CH 3 CN solvent, while a more homogeneous deposit, consisting of molecules with shorter conjugation system, forms in CH 2 Cl 2. Marked differences are also evidenced when the polymer is p-doped in the two different solvents.
In situ spectroelectrochemical characterization of poly(3,4-ethylenedioxythiophene)
Electrochimica Acta, 1999
The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT), in dierent electrolyte±solvent media was studied with cyclic voltammetry, in situ UV±VIS-spectroelectrochemistry, electrochemical quartz crystal microbalance technique (EQCM) and with in situ Fourier transform infrared (FTIR) spectroscopy using external and internal re¯ection techniques. The eect of polymerization current density and monomer concentration on the formation of the ®lm structure was studied. The redox reactions and the stability of charged ®lms of dierent thickness were studied with cyclic voltammetry and open circuit potentiometric measurements. FTIR spectra were recorded in situ during step-wise and continuous potential cycling of the polymer ®lms in dierent electrolytes. A characterization of the doping induced IR-bands has been made. # Electrochimica Acta 44 (1999) 2739±2750 0013-4686/99/$ -see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S 0 0 1 3 -4 6 8 6 ( 9 8 ) 0 0 4 0 5 -8 PERGAMON
Electrochemically Polymerized Terthiophene Derivatives Carrying Aromatic Substituents
Macromolecules, 1994
A series of terthiophene derivatives substitituted with an aryl group R at the 3'-position of the central thiophene [R = H (l), phenyl (2), 4-cyanophenyl (3), 4-methoxyphenyl(4), 4-pyridyl(5), 2-thienyl (6), or 3-methyl-2-thienyl (7)] have been polymerized. Although the Substituents force the monomers to a nonplanar conformation, thus preventing the extension of conjugation to the side group, they influence the polymerizability and the properties of the resulting polymers. Solubilities of the oxidation products and inductive effects of the substituents are discussed in order to explain the differences. As-grown films of poly-1,-2,-3,-4, and-6 were soluble in chlorinated organic solvents. Poly-1 consists of monomers and dimers, but the polymerization degree of other soluble polymers was larger, as determined by matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS). The polymers are mixtures of oligomers in all cases, and the highest observed oligomers were heptamers (with poly-2 and-3). With the exception of poly-1,-4, and-5, the films could be both anodically and cathodically doped. A splitting of the cathodic undoping peak in cyclic voltammograms was observed with poly-6 and-7 and polythiophene. This behavior is analogous to the anodic undoping, suggesting a mechanistic symmetry in the doping processes. Spectral changes during undoping are interpreted by reactions of ionic species having different effective conjugation lengths. compartment cell from solutions of the corresponding monomer (0.05 M) and tetrabutylammonium hexafluorophosphate (0.2 M)
Polímeros, 2020
This work reports the spectroelectrochemical and electrical behavior of electropolymerized donor-acceptor like (D-A) copolymer films, based on 3,4-ethylenedioxythiophene (EDOT) and beta-substituted electron-acceptor thiophenes. Initially, the copolymer films were deposited on indium tin oxide substrates, which spectroelectrochemistry measurements were carried out with an UV-Vis spectrophotometer. Hence, it was possible to observe the electrochromic properties of these materials, visualizing the color changing towards different potentials applied. The experiments have shown that these D-A like copolymers presented good electrochromic properties, such as optical contrast, coloration efficiency, and switching times. Additionally, films prepared on a platinum working electrode were investigated by electrochemical impedance spectroscopy, which has shown the electrical behavior of those copolymers and their potential as candidates to capacitive devices building. Therefore, the combination of electron-donor EDOT with those electron-acceptor monomers is indeed a useful strategy to tailoring and fine-tuning the physicochemical properties of polythiophenes with innovative applications.
Electrochimica Acta, 2008
Sulfonated thiophenes, sodium 2-(3-thienyloxy)ethanesulfonate (C 6 H 7 S 2 O 4 Na) and sodium 6-(3-thienyloxy)hexanesulfonate (C 10 H 15 S 2 O 4 Na), were synthesized and used in the fabrication of ion-selective electrodes (ISEs) sensitive and selective to Ag + . The Ag + -ISEs were prepared by galvanostatic electropolymerization of 3,4-ethylenedioxythiophene (EDOT) on glassy carbon (GC) electrodes, with either C 6 H 7 S 2 O 4 − or C 10 H 15 S 2 O 4 − as the charge compensator (doping ion) for p-doped poly(3,4-ethylenedioxythiophene) (PEDOT). Potentiometric measurements were carried out with these sensors, GC/PEDOT(C 6 H 7 S 2 O 4 − ) and GC/PEDOT(C 10 H 15 S 2 O 4 − ), to study and compare their sensitivity and selectivity to silver ions. PEDOT(C 6 H 7 S 2 O 4 − ) and PEDOT(C 10 H 15 S 2 O 4 − ) films were also studied by using other techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), electrochemical quartz crystal microbalance (EQCM) and Fourier transform infrared spectroscopy (FTIR).
Electrosynthesis and comparative studies on carboxyl-functionalized polythiophene derivatives
Electrochimica Acta, 2011
Electrochemical synthesis of a novel carboxylic acid functionalized polythiophene -poly(3-thiophenebutyric-acid), PTBA -has been realized. Its morphology, electrochemical, spectral and conducting properties have been compared to those of poly(3-thiophene-acetic-acid), PTAA, which is widely used to immobilise both bioactive molecules and inorganic nanoparticles. According to scanning electron microscopic (SEM) images, the difference in the real and geometric surface area of the modified electrodes is much more expressed in the case of PTBA. Both the symmetry of the cyclic voltammograms and the concurrent, sustained optical changes proved that this polymer possesses an improved and more stable redox activity. According to simultaneously performed in situ ac. impedance and UV-Vis measurements, both films could be uniformly transformed between the insulating and conducting forms, but PTAA exhibited some degradation. The development of the conducting state during the redox switching of both thiophene derivative polymers proved to be primarily connected to the formation of di-cationic species. The electrochemical quartz crystal microbalance (EQCM) results evidenced also differences between the two polymers, which difference can be interpreted by assuming the more expressed effect of the deprotonation-connected (self-) doping process in PTAA. The results confirm that the new conducting polymer, PTBA is much more convenient for being considered as the polymer matrix of practically applicable composites.
Macromolecules, 1999
In recent years, polythiophenes have attracted a great deal of research interest due to their electronic and electrochemical properties. The thiophene and bithiophene 2 monomers are easily obtained and derivatized to give structurally diverse polythiophenes. Thiophene has been substituted in the 3-position with a wide variety of functional groups and polymerized to give the corresponding -substituted polythiophenes. Polythiophenes substituted with alkyl, 3 alkoxy, 4 aryl, 5 chiral, 6 nucleobase, 2c and redox 7 groups have been synthesized and studied. In particular, poly(3-arylthiophenes) are showing promise as electrode materials for redox supercapacitors due to their ability to undergo reversible electrochemical doping and dedoping. 5a,b,8 However, to our knowledge the poly(3-arylthiophenes) have been limited to derivatives of benzene. 5 Therefore, we have initiated studies with the aims of attaching aromatic and heteroaromatic moieties other than phenyl directly to the thiophene ring and of investigating the corresponding polymers made both chemically and electrochemically. Herein we communicate results on our first system, namely, poly-[3-(9-tris(ethylene glycol) monomethyl ether)carbazoylthiophene].