Modification of the electrochemical and electronic properties of electrogenerated poly(3,4-ethylenedioxythiophene) by hydroxymethyl and oligo(oxyethylene)substituents

Ethylenedioxythiophene (EDOT) derivatives with hydroxymethyl and oligo(oxyethylene) groups covalently attached at the ethylenedioxy bridge have been synthesized. The hydroxymethyl group considerably increases the ability of EDOT to electropolymerize in water and the electroactivity of the polymer in aqueous media. The electrochemical and optical properties of the oligo(oxyethylene)-substituted polymer reveal a negative shift of the oxidation potential and a significant enhancement of the effective conjugation length with a 0.10 eV decrease of the bandgap. The optical spectra of the polymer undoped in the presence and absence of oxygen indicate a high sensitivity of the polymer towards molecular oxygen, suggesting possible spontaneous doping by molecular oxygen. (C) 2000 Elsevier Science S.A. All rights reserved.