Formation of Polythiophene and Related Polymers

Diaz et al. [599] have studied the electrooxidation of various aromatic monomers and oligomers including thiophene and its oligomers to identify relationships between the number of repeat units in the substrate molecule and the oxidation potential as well as the UV-vis absorption maximum of the oxidation product (soluble as well as deposited on the electrode). As can be expected based on theoretical calculations already mentioned, the oxidation potential shifts to less positive values with an increasing number of thiophene units in the educt, whereas the absorption maximum shifts considerably to longer wavelengths. 

Adsorption studies of thiophene on any of the electrode materials used most often are scant. Although data were obtained under ex situ conditions, the eonclusion that thiophene is adsorbed flat on the surface of Ag(111) reported by Baumgartner et al. [872] seems noteworthy because the assumed strong silver-sulfur interaction 

A change from a polymerization process that occurs in the solution phase toward a process that occurs on the surface in the case of weakfy adsorbing electrodes like ITO-glass has been concluded from a variety of experimental details obtained by et al. [888] with spectroelectrochemical and surface analytical tools during electropolymerization of thiophene. 

ESR spectra of a variety of electrooxidation products of thiophene oligomers, including orthogonally bridged dimers of 

Kilic et al. [896] performed a complete theoretical study of the electronic structure of thiophene, some of its oligomers, and some of its substituted derivatives. Conclusions with respect to preferred binding sites for coupling during polymerization, planarity, and so forth were reported. 

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