Effect of hydrophilic group on thin film formation using redox-active surfactants with an azobenzene group

Thin films of organic pigments were prepared at higher than pH 1 by the contact plating method using an anionic surfactant (AZNa, first figure of this article (part c) (n = 4)) containing an azobenzene moiety. The effects of hydrophilic group of the surfactants on the rate of following reaction of the reduction product were studied by cyclic voltammetry. The positive shift of the reduction peak potential of AZNa compared to those of cationic and non-ionic surfactants was ascribed to higher rate of following reaction of reduction product due to the presence of the anionic hydrophilic group of the surfactant. The present investigation revealed that the anionic hydrophilic group accelerates the cleavage of the NN bond of the azobenzene group. This phenomenon enabled us to prepare the organic thin film at higher pH condition.