Linear chains electropolymerization

In contrast to linear chains, branched alkyl groups drastically affect the effective conjugation of the PT backbone and, in some cases, the ability of the monomer to polymerize. Thus, attempts to electropolymerize 3-isopropyIthiophene (7) were unsuccessful, and 3-isobutylthiophene (8) leads to a polymer considerably less conjugated and less conductive than its linear analog [61,155]. In contrast, the oxidation potential and absorption maximum of the polymer from 3-isoamylthiophene (9) are similar to those of poly(3-amylthiophene) [61,205,206]. 

Electrochemical procedures have also progressed considerably. In particular, anodic electropolymerization has been tested in a great variety of experimental conditions in organic and acid media. The procedure constitutes a well established method for depositing doped or undoped thin polyphenylene films on platinum or other metals. The linearity and the DP of the PPP chains are very poor in organic media, but are much improved in acidic media (melt salts in the presence of Lewis acids, superacid media), or when the electrosynthesis is carried out at low temperature in SO2 with a Lewis acid (SbFs). 

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