Electrochemistry of Conductive Polymers: XIV . In Situ Spectroelectrochemical and Kinetic Studies on Poly(3‐Methylthiophene) Growth

Abstract

The growth mechanism of poly(3-methylthiophene) has been studied employing in situ spectroelectrochemical and kinetic measurements. Results indicate that: (i) the polymer film grows only when 3-methylthiophene is oxidized, suggesting that the radical-radical coupling reaction is important for the polymer growth; (ii) concentrations of intermediate species, i.e., radical cations of the trimer and tetramer, are maintained at a steady-state level during the growth; and (iii) both monomer and polymer concentrations appear in the rate expression, indicating that both the monomer and polymer participate in the polymer growth. The growth is not autocatalytic, and oxidation of both the monomer and oligomer or polymer is required for further growth of the polymer. The reaction order in the rate expression depends on experimental conditions ranging 0.5 -1 for the monomer, while it is about 0.5 for the polymer.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 157.182.150.22 Downloaded on 2015-03-10 to IP

In situ spectroelectrochemical study of dissolved oligomer products formed in the electrochemical polymerization of 3-methylthiophene

“…As a result, the probability of forming an ion pair of the oligomer +× species and the anion drops and, correspondingly, transfer of the oligomer radical-cations generated into the solution bulk decreases. On the whole, these results indicate the specific transfer of charged oligomers into the solution, which is in accord with the findings of Haier [8]. On the other hand, the subsequent transformations of these products indeed lead to the appearance of oligomers in solution, which, as shown by Correia [12], diffuse toward the anode and participate in the polymerization reaction, reducing its overvoltage.…”

“…1) with those for charged and neutral oligomers of unsubstituted and substituted thiophene [8]. Haier [8] has found that, depending on the environment and substituents, the radical-cations of the thiophene dimer, trimer, and tetramer display absorption maxima at~400-425,~530-557, and 614-648 nm, respectively. Hence, the strongest band with maximum at 530 nm in the spectra of the soluble polymerization products (Fig.…”

“…1a-c). According to Haier and Park [8], the long-wavelength band corresponds to absorption of the oligomer radical-cations (3MT trimer and, possibly, 3MT tetramer), while the bands at 300-400 nm are for neutral oligomers appearing due to reaction of these radical-cations with the 3MT radical-cation and/or their disproportionation into the corresponding dication and neutral oligomer or due to elimination of two protons by the dissolved dihydrodication. Another mechanism has also been proposed for annihilation of the oligomer radical-cations through nucleophilic addition of 3MT to these radical-cations with subsequent elimination of a proton [11].…”

“…the dissolved monomer [8]. It is clear that these ions, similar to all ions [9], characteristically undergo associative processes involving other ions and polar solvent molecules (dipoles) present in the system.…”

Performance of Polyaniline Coatings on Stainless Steel for Silver Recovery

“…It is well known that the polymer morphology and structure depend on polymerisation route [9,10]. For successful metal recovery it is important to obtain polymer with a large surface area.…”