Effect of the electropolymerisation conditions on the electrochemical, morphological and structural properties of PEDOTh films

摘要

Poly(3,4-ethylenedioxythiophene) (PEDOTh) films were deposited on platinum electrodes by consecutive potential scanning from acetonitrile solutions with 50 mM EDOTh. The effect of the supporting electrolyte used during electropolymerisation, namely LiClO4, TBAClO4 and TBAPF6, in the redox behaviour, surface morphology and degree of crystallinity of the films has been investigated by cyclic voltammetry, X-ray diffraction analysis and scanning electron microscopy, respectively. The use of LiClO4 leads to a higher electropolymerisation efficiency and an increase of electroactivity and crystallinity of the polymers. This electrolyte promotes the formation of a more compact morphology with clusters of different sizes. The film porosity increases when Li+ is substituted by a larger cation, TBA+. The PEDOTh layer obtained with $PF^{ - }_{6} $ as counter ion is more porous than the obtained with $CIO^{ - }_{4} $ and presents a fibrillar aspect. The influence of the scan rate was also studied for films obtained in TBAClO4, and high electropolymerisation efficiency and an increase of crystallinity were observed for a low scan rate. PEDOTh films with different number of growing cycles were obtained in LiClO4, pointing their redox behaviour to structural rearrangement during thickening; the thicker film presents higher structural organization. It was possible to prepare films in different conditions, but with the same electroactivity, showing the same structural arrangement.