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 th e polymeric chains include Ag, Cu, Ni, Pb, Fe and Cd. The metallizatio n process is achieved in three stages. The first is the complexation o f the PAH with various transition metal salts. The second is the dopin g of the resulting PAM-metal complex films with an ethanol solution of iodine. The third is the reduction of the iodine-doped films with a s odium boron hydride (NaBH4) aqueous solution. The PAM-metal complexes have been characterized by IR, elemental analysis and UV-visible spect rophotometry. The doping of PAM-metal complex films into an ethanol so lution of iodine and into an NaBH4 aqueous solution was found to be es sential for changing them from insulators to conductors. The effects o f the dopant concentration, temperature and time of exposure on the co nductivity of the PAM-metal complex films were studied. In all cases t he 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% NaBH4 aqueous solution at 65 degrees C for 1 min gave a minim um surface resistivity in the range 10(-5-)10(-1) Ohm cm(-2). The surf ace resistivity of these films is influenced by the type of metal inco rporated into the polymeric chain. It decreases in the following order : Fe > Pb > Ni > Cu > Ag. For a particular metal, the surface resistiv ity 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 th e 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 generat ed on the surfaces of the films was believed to be responsible for the ir electrical conductivity. These metallized films maintain good mecha nical and thermal properties. (C) 1998 Elsevier Science Ltd. All right s reserved.