Surface modification and functionalization of electroactive polymer films

Surface modification of electroactive polyaniline (PANi) films by gas plasm a 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 disch arge and VUV, followed by atmospheric exposure, resulted in the oxidation o f the carbon atoms to various extents. Carbon oxidation, in turn, caused a decrease in the intrinsic oxidation state ([=N -/[- NH -] ratio) of the ani line polymer. The as-cast and noncrosslinked emeraldine (EM-25) film of PAN i exhibited a surface micro-hardness of about 1 GPa. The hardness was furth er 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 styrenesulf onic acid could give vise to semi-conductive and super-hard-surfaced PANi f ilms having micro-hardness values approaching 20 GPa. This surface hardness is comparable to those reported for the super-hard-surfaced conventional p olymers from high-energy ion-beam bombardment. (C) 1999 John Wiley & Sons, Ltd.