Comparison of oxidation polymerization methods of thiophene in aqueous medium and its mechanism

Precipitation method of oxidation polymerization for preparing polythiophene was carried out as well as dispersion and emulsion methods in aqueous medium by using (NH 4 ) 2 S 2 O 8 and CuCl 2 as the oxidant and catalyst, respectively. In precipitation method, ethanol was served as an auxiliary solvent to water. The effective conjugated length (ECL) of the obtained polythiophene was demonstrated to be evaluated by the UV absorption spectrum. The ECL of the polythiophene gradually increases with the rise of the content of ethanol in the mixed solvent in precipitation polymerization, and it was higher comparing to the ECL of the product prepared by aqueous dispersion or emulsion method. An electron transition mechanism of the oxidation polymerization of thiophene was suggested.