Super-hard-surfaced polyaniline films by bulk and surface modifications

The hardnesses of conventional thermoplastics lie between 0.1-0.6 GPa. The as-cast emeraldine base (EB) exhibits a surface microhardness of 1-2 GPa. The hardness is increased to 6 GPa in highly crosslinked EB (x-EB) film and can be further enhanced to about 8 GPa through protonation or through reduction. Surface modification of x-EB films via graft copolymerization with acrylic acid and styrenesulfonic acid readily gives rise to a semi-conductive, super-hard surface, having a micro-hardness of about 20 GPa. This surface hardness is higher than many of known super-hard-surfaced conventional polymers from high-energy ion-beam bombardments.