Surface modification and functionalization of electroactive polymer films

Abstract

Surface modification of electroactive polyaniline (PANi) films by gas plasma treatment, corona discharge treatment, vacuum ultra-violet (VUV) exposure, and surface graft copolymerization has been carried out. Exposure of the nigraniline-like films of PANi to argon plasma, oxygen plasma, corona discharge and VUV, followed by atmospheric exposure, resulted in the oxidation of the carbon atoms to various extents. Carbon oxidation, in turn, caused a decrease in the intrinsic oxidation state ([N/[NH] ratio) of the aniline polymer. The as-cast and noncrosslinked emeraldine (EM-25) film of PANi exhibited a surface micro-hardness of about 1 GPa. The hardness was further enhanced to about 6 GPa in the highly crosslinked EM (EM-150) film after one cycle of acid–base treatment. Surface modification of the crosslinked EM film via surface graft copolymerization with acrylic acid or styrenesulfonic acid could give rise to semi-conductive and super-hard-surfaced PANi films having micro-hardness values approaching 20 GPa. This surface hardness is comparable to those reported for the super-hard-surfaced conventional polymers from high-energy ion-beam bombardment. Copyright © 1999 John Wiley & Sons, Ltd.