Special Electropolymerization Methods

Electrochemistry is one of the most promising areas in the research of conducting polymers. Thus, the method of choice for preparing conducting polymers, with the exception of PA, is the anodic oxidation of suitable monomeric species such as pyrrole [3], thiophene [4], or aniline [5]. Several aspects of electrosynthesis are of relevance for electrochemists. First, there is the deposition process of the polymers at the electrode surface, which involves nucleation-and-growth steps [6]. Second, to analyze these phenomena correctly, one has to know the mechanism of electropolymerization [7, 8]. And thirdly, there is the problem of the optimization of the mechanical, electrical, and optical material properties produced by the special parameters of electropolymerization. 

Oxide, flouride, and polymeric films, as well as certain others, are used as protective coatings for HTSC materials (for example, see [505]). The electrodeposition of conducting polymers such as polypyrrole [433,491, 493, 506], polythiophene and its derivatives [493, 507], and polyaniline [478] is the most effective process. Anodic electropolymerization in acetonitrile solutions proceeds without any degradation of the HTSC substrate and ensures continuous and uniform coatings. Apparently, this method is promising not only for the fabrication of compositions with special properties based on HTSC [50, 28,295] as mentioned above, but also for the creation of junctions with special characteristics [507]. 

Electropolymerization is typically a method used in the preparation of CPs. Electroinitiated polymerization has been used for special purposes with common vinyl monomers. Electropolymerization is, however, a stoichiometric method in which 2.1-2.7 equivalents of electricity are consumed per monomer unit. Usually electrochemical oxidation is used and the polymer is deposited on the anode. If the end monomers are not taken into account, two equivalents are needed per monomer for the bond formation. The rest is consumed for the oxidation, i.e., doping of the polymer. Schematically, the coupling reaction can be shown as in Fig. 7a. 

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