A spectroelectrochemical study of conducting pyrrole-N-methylpyrrole copolymers in nonaqueous solution (original) (raw)
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2011
C opolymerizations of pyrrole (Py) with N-pentylpyrrole (NPPy) and N-dodecylpyrrole (NDPy) were carried out by chemical and electrochemical oxidation methods. Nanoparticles made of conjugate copolymers with different feed ratios of monomers were prepared by chemical polymerization (conventional and interfacial methods) in presence of iron (III) chloride hexahydrate (FeCl 3 .6H 2 O) as the oxidant. Nanostructure copolymers with higher conductivity were synthesized by simply tuning the preparation conditions in a two-phase medium (toluene-water as solvents). The Npentylpyrrole and N-dodecylpyrrole monomers were synthesized with higher purity from pyrrole. Fourier transform infrared spectroscopy, scanning electron microscopy and four probe conductivity measurement techniques were applied for the characterization of the copolymers. The conductivity of the copolymers obtained by interfacial method using toluene as an organic phase was 5-6 times higher than the copolymer obtained by a conventional method (for molar ratio of Py:NPPy, 30:70). In electrochemical method, copolymer thin films were synthesized with different feed ratios of monomers by cyclic voltammetry in lithium perchlorate-acetonitrile (LiClO 4 /CH 3 CN) electrolyte on the surface of the glassy carbon (GC) as the working electrode. Deposition conditions on the GC, influence of the molar ratio of monomers on the electroactivity and formation of copolymers were studied using cyclic voltammetry.
Polymer, 2006
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
The copolymerization of N-Methylpyrrole (N-MPy) and N-ethylcarbazole (ECz) by chemical and electrochemical methods is investigated in detail. Random copolymers of poly[N-Methylpyrrole-N-ethylcarbazole], P[N-MPy-co-ECz], were synthesized in the presence of ceric ammonium nitrate (CAN) in acetonitrile. Electrocopolymerization of N-MPy, and ECz was carried out in various solvents on platinum electrode. Propylene carbonate (PC) was found to be the most suitable solvent for film formation. The effects of sweep rate, supporting electrolyte type, mole ratio, and temperature on the electropolymerization were discussed. The electrochemical properties of Poly(N-ethylcarbazole), (PECz) were improved on copolymerizing it with N-MPy. A copolymerization mechanism has been suggested. The resulting copolymer was characterized by UV-Vis and FT-IR spectroscopic methods, as well as cyclic voltammetric measurements. Ã Given potentials have deviation ¼ AE0.003 V. 1 Polymer oxidation potential, V. 2 Monomer oxidation potential, V. a Initial feed ratio of monomers, n N-MPy =n ECz ¼ 2.
Physicochemical and morphological properties of poly(aniline-co-pyrrole
Journal of Materials Science, 2010
Copolymers of aniline and pyrrole have been prepared by chemical oxidative polymerization of 1:1 mixture of aniline and pyrrole monomer with ammonium per sulphate and ferric chloride. The structural and morphological properties were studied by X-ray diffraction and scanning electron microscopy. Both copolymers showed an amorphous behaviour compared to their homopolymers. SEM micrographs of poly(aniline-pyrrole) copolymer showed agglomerated spherical structures where as poly(2,5 dimethoxyanilinepyrrole) showed disordered structures of spherical agglomerates. The copolymers showed improved UV-Vis absorption with the broad peak from 2 450-850 nm. The copolymers exhibited a lower conductivity compared to the homopolymers. It is also observed that the PDMA-PPY copolymer obeyed ohms law where as PANI-PPY behaved like a diode.
Polymer International, 2007
The structural, electric and electronic properties of copolymers derived from mixtures of Nmethylpyrrole and 3,4-ethylenedioxythiophene (EDOT) with various concentration ratios have been investigated and, additionally, compared with those of the corresponding homopolymers. The electropolymerization kinetics of all the generated copolymers and the homopolymers was examined in terms of current productivity using chronoamperometry. The chemical structure of the linkages between adjacent monomers and the microstructure of the chains were investigated using Fourier transform infrared spectroscopy and quantum mechanical calculations, respectively. The results indicate that the linkages between monomeric units formed during the anodic copolymerization are of the α -α type, while the microstructure of the copolymers depends on the EDOT content. Theoretical calculations were also used to examine the electronic properties of the systems under study, while the conductivity and the electrical stability were studied using the sheet-resistance method. Interestingly, the electric properties are consistent with the random and block microstructures predicted for the copolymers with low and high EDOT content, respectively.
The copolymerization of N-Methylpyrrole (N-MPy) and N-ethylcarbazole (ECz) by chemical and electrochemical methods is investigated in detail. Random copolymers of poly[N-Methylpyrrole-N-ethylcarbazole], P[N-MPy-co-ECz], were synthesized in the presence of ceric ammonium nitrate (CAN) in acetonitrile. Electrocopolymerization of N-MPy, and ECz was carried out in various solvents on platinum electrode. Propylene carbonate (PC) was found to be the most suitable solvent for film formation. The effects of sweep rate, supporting electrolyte type, mole ratio, and temperature on the electropolymerization were discussed. The electrochemical properties of Poly(N-ethylcarbazole), (PECz) were improved on copolymerizing it with N-MPy. A copolymerization mechanism has been suggested. The resulting copolymer was characterized by UV-Vis and FT-IR spectroscopic methods, as well as cyclic voltammetric measurements.
Applied Surface Science, 2015
A direct electrochemical copolymerization of pyrrole-formyl pyrrole (Py-co-FPy) was carried out by oxidative copolymerization of formyl pyrrole and pyrrole in LiClO 4 aqueous solution through galvanostatic method. The (Py-co-FPy) copolymer was characterized using Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FESEM), energy-filtering transmission electron microscope (EFTEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The FESEM images showed that the synthesized copolymer had a hollow whelk-like helixes structure, which justifies the enhancement of charge transportation through the copolymer film. Cyclic voltammetry studies revealed that the electrocatalytic activity of synthesized copolymer has improved and the surface coverage in copolymer enhanced 1.6 times compared to polypyrrole alone. Besides, (Py-co-FPy) copolymer showed 2.5 times lower electrochemical charge transfer resistance (R ct) value in impedance spectroscopy. Therefore, this copolymer has a strong potential to be used in several applications such as sensor applications.
Copolymers Of Pyrrole And Α,Ω-Dithienyl Terminated Poly(Ethylene Glycol)
2015
This work presents synthesis of α,ω-dithienyl<br> terminated poly(ethylene glycol) (PEGTh) capable for further chain<br> extension by either chemical or electrochemical polymeriztion.<br> PEGTh was characterized by FTIR and 1H-NMR. Further<br> copolymerization of PEGTh and pyrrole (Py) was performed by<br> chemical oxidative polymerization using ceric (IV) salt as an oxidant<br> (PPy-PEGTh). PEG without end group modification was used<br> directly to prepare copolymers with Py by Ce (IV) salt (PPy-PEG).<br> Block copolymers with mole ratio of pyrrole to PEGTh (PEG) 50:1<br> and 10:1 were synthesized. The electrical conductivities of<br> copolymers PPy-PEGTh and PPy-PEG were determined by four<br> point probe technique. Influence of the synthetic route and content of<br> the insulating segment on conductivity and yield of the copolymers<br> were investigated.