Polyaniline and Related Polymers

The following sections cover the preferred electrochemical aspects of the formation and the materials properties of the investigated monomers and their relatives as revealed with spectroscopic and surface sensitive methods. Results obtained with other methods (scanning probe microscopies and, especially, traditional electrochemical techniques) are quoted only in passing when deemed necessary for a better understanding of the spectroelectrochem-ical results. Because of the numerous reviews that cover a very broad range of conceivable and potential applications, no attention is paid to this aspect. 

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Recently developed catalyst systems make it possible to construct carbon (.v/>2 )-catbon (sp3) bonds and carbon-nitrogen bonds under mild conditions (Scheme 9.14).19,20 These new developments have also been incorporated into step-growth polymerization. Kanbara et al. reported the synthesis of polyanilines and related polymers in 1996 (Scheme 9.15).21 Wang and Wu reported the synthesis of polyketones in 1999 (Scheme 9.16).22... 

This chapter will consider in detail only PHCs and in particular pyrrole- and thiophene-based systems. This limitation implies that other important classes of polyconjugated polymers, such as polyacetylene, polyaiylenes, polyanilines, and related polymers, will not be treated. 

Properties of Polyaniline and Related Polymers and their Electrochemically... 

Redox Processes and Electrocatalysis at Polyaniline and Related Polymers... 

The preparation of polypyrrole, polythiophene, polyaniline, and related conducting polymers demonstrates principles of electrochemical synthesis that are more widely applicable, and it is instructive to examine these in detail. 

Brown, C. E., Kovacic, P, Welch, K. J., Cody, R. B., Hein, R. E., and Kinsinger, J. A., "Laser Desorption/Fourier Transform Mass Spectra of Polyfphenylene sulfide), Polyaniline, Poly(vinyl phenol). Polypyrene, and Related Oligomers Evidence for Carbon Clusters and Eeasibility of Physical Dimension Measurement," /. Polym. Sci. PolyttL Chem. Ed., 26,131-148,1988. 

The growth of the polymer film can be followed by cyclic voltammetry since the current peaks related to the polymer redox transformations increase as more and more polymer is deposited. The increase of the surface mass can be detected by using an -> electrochemical quartz microbalance. Such an example is shown in the Figure. In this experiment the positive potential limit of cycling was gradually decreased in order to avoid overoxidation of the polyaniline (PANl) formed. It does not affect the rate of polymerization, i.e., the film growth, since the electrooxidation of aniline is an autocatalytic process. 

Faradaic in nature and therefore is different farm Pseudocapacitance usually originates from electrosorption (specific adsorption) processes and related partial electron transfer or surface charging (Section 5-5). On metal oxide "supercapacitor" types of electrodes (such as iridium and ruthenium oxides) possessing several oxidation states, pseudocapacitance originates from potential dependence of multiple oxidation/reduction couples that are active on the surfaces of the materials. Another coiiunon source of pseudocapacitance is charging-discharging of redox-active polymers such as polyaniline and polypyrrole. 

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