Electrochemical, spectroscopic and electrogravimetric detection of oligomers occluded in electrochemically synthesized poly(3,4-ethylenedioxythiophene) films

This paper shows that oligomers are retained inside the polymer film during the electrosynthesis of poly(3,4-ethylenedioxythiophene), PEDOT, in aqueous media. The behavior of the electrochemically generated PEDOT film is highly dependent on the presence of these oligomers. A detailed study of the release of oligomers trapped in the PEDOT film has been carried out using bidimensional spectroelectrochemistry (BSEC), spectroelectrochemical quartz crystal microbalance (SEQCM) and scanning electrochemical microscopy (SECM). These multiresponse techniques have allowed us to determine when these EDOT oligomers are released into solution and to investigate their electrochromic properties. Mass spectroscopy measurements revealed that most of these oligomers consist of four or six monomer units, which seem to be the most stable species in aqueous solution.