Crosslinking and its effects on polyaniline films

Abstract

Polyaniline base films with varying degrees of crosslinking were cast from N-methylpyrrolidinone solutions at different processing temperatures. The effects of crosslinking on the films' physical properties (solubility, surface morphology, tensile strength), doping characteristics, and transport of ions across the films were investigated. The presence of crosslinking in the film significantly decreases its solubility and enhances its strength, but a comparison of the surface anion/N ratio (as determined by X-ray photoelectron spectroscopy) and the bulk anion/N ratio (as determined from elemental analysis) shows that uniform doping of the crosslinked film by acids is much more difficult to achieve. The transport of H+ ions through the base film is characterized by an initial time lag followed by a steady-state flux. Both of these parameters are dependent on the degree of crosslinking in the film. It appears that doping of the base film and transport of ions across a doped film are affected differently by crosslinking in the film.