Formation of Polypyrrole and Related Polymers

PPy can be synthesized from both aqueous and nonaqueous electrolyte solutions. The influence of the composition of the electropolymerization solution on the properties of the deposited PPy film has been studied with respect to a variety of material properties [604-608]. 

Genies et al. [613] measured the UV-vis absorption during the oxidation and polymerization of pyrrole as a function of time. The radical coupling step was foimd to be rate determining. The initial stage of PPy film formation resembles nucleation during metal deposition. 

Abrantes and Correia [622] employed the probe beam deflection technique to investigate the early stages of growth of poly(3-methylthiophene) and PPy. Their results support the assumption (in eontrast to the bulk of the reports published so far) that oligomer formation is not determinant for PPy deposition, quite in contrast to the formation of the thiophene-based polymer. 

The influence of the dopant anion on film properties was studied by Krivan and Visy [626]. With sodium dodecylsulfate, an increase of redox capacity and a higher doping level were observed. Results obtained with UV-vis spectroscopy and their interpretation indicate that structural changes that result in a decreased hy-drophobicity may be a possible cause. 

Using the valence effective Hamiltonian (VEH), Bredas et al. [627] calculated optical as well as electrochemical properties of pyrrole and PPy. TTieir data agree nicely with reported experimental results. 

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