Structure–property relationships for novel wholly aromatic polyamide-hydrazides containing various proportions of para-phenylene and meta-phenylene units : IV Preparation and characterization of metallized plastic films through transition metal complexation

Abstract

A series of metallized plastic films based on several polyamide-hydrazides has been synthesized. Metallization process was achieved via complexation of the polymers with various transition metal salts, followed by surface modification of the resulting complex films by a chemical reduction. The complexation reaction was simply carried out by stirring the mixed N, N-dimethylacetamide [DMAc] solutions of the polymer and the metal salt at room temperature overnight. The metals incorporated into the polymeric chains include silver, copper and cobalt. The complex solutions appeared clear, highly viscous, colored and could readily be cast into films. The complex films were further modified by a chemical treatment using an aqueous sodium boro hydride solution. The complexes were investigated by elemental analyses, infrared spectra and ultraviolet-visible spectrophotometry. The results revealed that metal ions were complexed with polymer repeating unit by a ratio of 1:1. These complexes showed a good solubility in several common organic solvents. Scanning electron microscopy and X-ray diffraction were employed to characterize the surfaces of the complex films before and after modification. Upon treatment with a reducing agent, all the complex films showed a significant change in their colors to a shiny metallic appearance. Their surfaces changed from smooth to very rough appearance as observed by scanning electron microscope. This can be attributed to the abundant aggregation of metal particles on the surfaces of the complex films which develop to form a metallic surface layer. This result is strongly evidenced by X-ray diffraction. All the metal complexes showed better thermal and thermooxidative stability relative to those of the corresponding polymers in terms of initial degradation temperatures as well as residual weight (%) at a particular temperature. The data also demonstrate how the thermal and thermooxidative stability of these complexes are significantly affected both by the type of the metal incorporated and by the nature of the polymer. Further, the metallized films maintain good mechanical properties.