Novel wholly aromatic polyamide-hydrazides-VII. Metallization of polymers through transition metal complexation

Several polyamide-hydrazide (PAH)-transition metal complexes have been prepared as metallized plastic films. The metals incorporated into the polymeric chains include Ag, Cu, Ni, Pb, Fe and Cd. The metallization process is achieved in three stages. The first is the complexation of the PAH with various transition metal salts. The second is the doping of the resulting PAH-metal complex films with an ethanol solution of iodine. The third is the reduction of the iodine-doped films with a sodium boron hydride (NaBH 4 ) aqueous solution. The PAH-metal complexes have been characterized by IR, elemental analysis and UV-visible spectrophotometry. The doping of PAH-metal complex films into an ethanol solution of iodine and into an NaBH 4 aqueous solution was found to be essential for changing them from insulators to conductors. The effects of the dopant concentration, temperature and time of exposure on the conductivity of the PAH-metal complex films were studied. In all cases the use of a 4-6 wt% ethanol solution of iodine at room temperature for 5 min gave lower surface resistivity of the iodine-doped films, while a 5 wt% NaBH 4 aqueous solution at 65°C for 1 min gave a minimum surface resistivity in the range 10 -5 -10 -1 Ω cm -2 . The surface resistivity of these films is influenced by the type of metal incorporated into the polymeric chain. It decreases in the following order: Fe > Pb > Ni > Cu > Ag. For a particular metal, the surface resistivity of the films decreases with increasing metal content. Further, the surface resistivity is affected by polymer structural variations and is decreased by increasing the p-oriented phenylene ring content of the polymer. The surfaces of these films were proved to be metallized by means of scanning electron microscopy, X-ray diffraction and electron spectroscopy for chemical analysis (ESCA). The metallic layer generated on the surfaces of the films was believed to be responsible for their electrical conductivity. These metallized films maintain good mechanical and thermal properties.