Diffusion limited behaviour of hydrophobised thin UV-curable nanocomposite coatings against model electrolyte

Abstract

Two different approaches were used to modify a UV-curing resin based on polyester chemistry, namely molecular and nano-particular approaches. In the molecular approach a hydrophobic compound, glycidyl neodecanoate, was reacted with the resin and was fixed on the polymer backbone. In the nano-particular approach a nano-clay was used to modify the resin in a physical manner. The electrochemical properties of the coating films were investigated using electrochemical impedance spectroscopy. In all cases a broadening of the complex plane graph in the direction of real impedance axis was observed. It was necessary in all cases to incorporate a finite length warburg element into the equivalent circuit to account for this broadening effect. The presence of this element was attributed to an intermediate case of anomalous diffusion of charge carriers through the dense polymeric network of the UV-cured films. EIS investigations of the UV-cured films show that both molecular and nano-particular modifications cause the electrochemical properties of the film to remain constant for a longer immersion time compared to unmodified resin.