Neutral, Undoped PEDOT by Oxidative Polymerization

To suppress premature doping, the presence of a stoichiometric excess of iron(III) chloride over EDOT during the reaction must be avoided. 

Furthermore, the use of an appropriate solvent— for example, a halogenated hydrocarbon—and the presence of an acid acceptor like calcium carbonate are helpful to isolate neutral PEDOT in acceptable yields in the lower two-digit percent range. Because even under optimal conditions doping cannot be excluded completely, the yield of undoped PEDOT is limited. 

As iron(III) chloride additionally functions as Lewis acid, trace amounts of the EDOT dimer and trimer (see Chapter 5) could be detected in the product iH-NMR-spectroscopically by the clearly separated peak at 5.42 ppm (o).  

Infrared spectrum of oxidatively prepared undoped, neutral PEDOT. (Adapted from K. Reuter, 2001. Unpublished results.) 

Comparison of IR Data of Different Undoped PEDOT Grades 

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