Effects of high frequency ultrasound irradiation on incorporation of SiO2 particles within polypyrrole films

This paper deals with the effect of ultrasound on polypyrrole/SiO2 composite film elaboration through various steps (particle dispersion, electrosynthesis). Experiments were carried out on stainless steel in phosphoric acid solution. An efficient method for dispersion of SiO2 particles prior to electropolymerization, based on low frequency irradiation (20 kHz), was proposed. It was shown that mechanical effects of high frequency ultrasound (i.e. mass transfer improvement) led to enhancement of electropolymerization kinetics. Scanning electron microscopy imaging and glow discharge optical emission spectroscopy revealed localization of SiO2 particles in the outer region of the films as well as better incorporation of particles under high frequency ultrasound irradiation. Finally, anticorrosion behavior of formed films was investigated in sodium chloride solution by Open Circuit Potential and anodic polarization methods. The results showed that polypyrrole/SiO2 films elaborated under ultrasound irradiation exhibit the best protective performances.