Polythiophenes Yamamoto polymerization

Polythiophene, as obtained from Grignard-coupling polymerization from dibromothiophene, was vacuum deposited on various substrates and studied by electron diffraction by Yamamoto el al. [51]. They report diffraction patterns obtained from a single crystalline region, showing 44 distinct reflections of hkO-type. The indexing is in accordance with the a and 6-axes values obtained by Mo el al. Curiously the crystal is oriented with its c-axis perpendicular to the substrate, and the c-axis parameter could not be determined. The crystal is reported to deteriorate under the electron beam. 

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... 

Yamamoto Method. Yamamoto et al. [423] prepared polythiophene by treating 2,5-dibromothiophene with Mg and catalyzing the polymerization by Ni(bipyridine)2Cl2 (Fig. 15). A similar... 

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