Influence of different dopants on the adsorption, morphology, and properties of self-assembled films of poly(o-ethoxyaniline)

Abstract

Self-assembled films of poly(o-ethoxyaniline)-POEA alternated with sulfonated lignin (SL)-were successfully produced, and their kinetics of formation and growth investigated for different dopants (hydrochloric acid, methanesulfonic acid, p-toluenesulfonic acid, and camphorsulfonic acid). These films were characterized by ultraviolet-visible spectroscopy, atomic force microscopy, surface potential, and electrical resistance measurements. It has been observed that the bulkiest dopants led to a greater time for the polymer deposition and greater amount of material adsorbed. This can be explained by the lower mobility and lower solvation of the bulkiest dopant counterions, which led to a higher screening effect of the charges present in the POEA chains and therefore to a more compact molecular conformation. The morphology of the POEA films were also greatly affected by the type of dopant used, being rougher for the bulkiest dopants. The POEA films also exhibited different electrical responses upon ethylene exposure depending on the dopant, indicating a promising use for gas sensor applications.