Anions polyaniline synthesis

Completely different monomers were called for. Before long, three of today s workhorses had been identified pyrrole, aniline and thiophene. In Japan, Yamamoto [38] and in Germany, Kossmehl [39] synthesized polythiophene doped with pentafluoroarsenate. At the same time, the possibilities of electrochemical polymerization were recognized. At the IBM Lab in San Jose, Diaz used oxidative electrochemical polymerization to prepare polypyrrole [40] and polyaniline. [41] Electrochemical synthesis forms the polymer in its doped state, with the counter-ion (usually an anion) incorporated from the electrolyte. This mechanism permits the selection of a wider range of anions, including those which are not amenable to vapor-phase processes, such as perchlorate and tetra-fluoroborate. Electrochemical doping also overcomes an issue associated with dopants... 

Ternary composites with electroactive components were also discussed by Gomez-Romero and coworkers in one of their recent publications [48]. The ternary composites consisted of doped-polyaniline (PANI) or doped-polypyrrole (Ppy) intercalated into V2O5 xerogels. The dopant anion for the conducting polymers was [Fe(CN)g] (HCF), derived from H3Fe(CN)6. More specifically, the synthesis of Ppy/HCF/V205 and PANI/HCFA 20s was carried out by treating the monomer (aniline or pyrrole)... 

For the synthesis of polyaniline designed for battery electrodes, Fe(C104)3 and Cu(BF4)2 are preferable as oxidizing agents, because the products contain CIO 4 or BFi anions, which are commonly used in lithium secondary batteries. Polyaniline synthesized by Cu(Bp4)2 has a fibrous morphology [57],... 

Berlin et al. [166] reported the synthesis of n-doped polycationic polythiophenes using thiophene monomer functionalized with ammonium groups (see Figure 1.20 (7)). The polymer exhibits reversible p-and n-doping characteristics. The n-doping process and the associated expulsion of anions, is reportedly fast and independent of cation size, and the in situ conductivity is reportedly 2 x 10 S/cm. Kumar et al. synthesized a fully sulfonated n-doped polyaniline electrochemically using an acetonitrile-water (4 1) mixture [180]. The n-doping was confirmed... 

A new class of water soluble polypyrrole has been prepared by selfdoping of the polymer. These self-doped polypyrroles can be prepared electrochemically or chemically, using various dopant anions covalently bound to the polymer backbone. The self-doped sulfonated polypyrrole is most commonly synthesized electrochemically in nonaqueous media. Electrochemical synthesis in aqueous media and chemical synthesis are not typically used, presumably due to issues with overoxidation. The postpolymerization modification of polypyrrole, in a manner similar to that used to form sulfonated polyaniline is rare [41]. The various synthetic approaches and properties of the polymer are discussed in the following sections. 

The most important characteristic of monomer molecules for the formation of a conducting polymer is the requirement for the conversion of a closed-shell system to a corresponding cation or anion radical and the stability of the product to form during the process. Polyaniline is prepared by either chemical or electrochemical oxidation of aniline under acidic conditions. An aqueous medium is preferred. The synthesis of polymer by either chemical or electrochemical methods depends upon the intended application of the polymer. Whenever thin films and better-ordered polymers are required an electrochemical method is preferred. 

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