Towards carboxylic acid-functionalized aniline monomers: Chemical synthesis, electropolymerization and characterization

Abstract

Polyaniline is one of the most studied conducting polymers because of its high stability and interesting combination of redox and proton doping properties. Moreover, it is possible to use the amino group of polyaniline to graft a substituent to obtain polyaniline derivatives. In the present study, aniline monomers were functionalized by an alkyl chain terminated by a carboxyl group at the N-position of the monomers in an attempt to obtain a series of carboxylic acid-functionalized polyanilines. The electro-oxidation of the modified aniline monomers was studied in HCl and H3PO4 acidic solutions with potentiodynamic and potentiostatic methods. The influence of the nature of the solvent and the length of the grafted alkyl chain on the thickness, morphological features and wettability of the carboxyl-functionalized polyaniline films was studied. In particular, the nature of the acid used strongly impacted the film properties leading to thinner, smoother, more hydrophilic, more adhesive and more homogeneous films when the electropolymerization was performed in phosphoric acid solutions.