Polyimide-metal oxide (Co304 or CuO) composite films have been prepared via in situ thermal decomposition of cobalt (II) chloride or bis (trifluoroacetylacetonato) copper (II). A soluble polyimide (XU-218) and its corresponding prepolymer (polyamide acid) were individually employed as the reaction matrix. The resulting composites exhibited a greater metal oxide concentration at the air interface with polyamide acid as the reaction matrix. The water of imidization that is released during the concurrent polyamide acid cure and additive decomposition is believed to promote metal migration and oxide formation. In contrast, XU-218 doped with either HAuCl4 • 3H2O or AgNO3 yields surface gold or silver when thermolyzed (300 °C).
SynopsisHigh-temperature polyimide films with metallic gold surfaces can be fabricated by the incorporation of a soluble metal salt into a solution of polyamic acid. Thermal treatment of these solutions produces the polyimide, decomposes the metal salt to metallic gold, and promotes the formation and growth of the metallized surface. What appeared to be a continuous metallic surface was actually composed of large gold aggregates. It is suspected that the formation of colloidal gold during the initial thermal treatment provides precursors to the large metal aggregates. Thermal treatment has been shown to influence the size and distribution of the aggregates. The shape of the aggregates suggests that diffusion-limited aggregation may be responsible for the unique shape of some of the gold aggregates. 4,4'-bis(aminophenyl)ether) containing HAuCl, . H,O.EXPERIMENTAL N-methyl pyrollidone (NMP) was dried over calcium hydride, vacuum distilled, and stored under nitrogen prior to use. The aromatic diamine,
Polyimide films with metallic surfaces were produced by thermal treatment of solutions containing HAuCl4⋅3H2O, hydrogen tetrachloroaurate trihydrate, and either Ciba–Geigy XU 218, poly[5(6)-amino-1-(4′ phenyl)-1,3,3 trimethylindane-3,3′,4,4′-benzophenonetetracarboxylimide] or BTDA-ODA, poly [ p, p′-oxybis (phenylene)-3,3′,4,4′-benzophenonetetracarboxylimide]. Scanning electron microscopy indicated that 0.1-μ particles covered a large portion of the air side surface; whereas, 10-μ particles covered the glass side surface of these films. Auger electron spectroscopy and x-ray photoelectron spectroscopy (XPS) indicated that the particles were gold in the metallic state. Model imide compounds were synthesized and used to evaluate the XPS spectra of both unmodified and gold containing films. Surface analysis data suggested that only a small amount of gold was located within the XPS sampling depth and that the observed gold particles resided underneath a polyimide overlayer. The discrete metal particles had an unexpected influence on the photoelectron spectra of the polyimide and the influence was dependent on particle size. A schematic model of the multilayered modified film surface was developed and the model further probed by electron flood gun and metal vapor deposition studies.
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