Relation between structure and ions mobility in polypyrrole electrosynthesized under high frequency ultrasound irradiation

High frequency ultrasound (500 kHz) was shown to have very interesting effects on PPy elaborated with various counter-ions: perchlorate (ClO4−), p-toluenesulfonate (TS−) and molybdate (MoO42−). Changes in polymer growth for sonicated films were highlighted by Atomic Force Microscopy (AFM) while Scanning Electron Microscopy (SEM) showed thinner and more homogeneous surface structure for PPy elaborated under ultrasound. Mobility of ions within PPy films was studied by electrochemical techniques, sonicated PPy seems to have much denser and more compact structure than silent one's. Specific electrochemical behavior was evidenced for sonicated PPy/MoO42− as well as unique ions reparation within the organic matrix, thanks to Glow Discharge Optical Emission Spectroscopy (GDOES). This technique was used in original manner to study presence and repartition of doping ions in the film. X-Ray Photoelectron Spectroscopy (XPS) analyses showed an increase in doping level for sonicated PPy but electrical conductivity measurements let appear a decrease in conductivity for PPy elaborated under sonication.

► High frequency ultrasound is used during electropolymerization. ► It leads to structural changes during polymer growing. ► Polymer's surface morphology is thinner and more homogeneous and its compactness is bigger. ► Electrochemical behavior is specific due to different mobility of ions in the film. ► Influence on doping level and electrical conductivity is discussed.