Polyimides can be infused with silver complexes by the use of supercritical fluids. Highly reflective polyimide films were formed by infusing (1,5-cyclooctadiene-1,1,1,5,5,5-hexafluoroacetylacetonato)silver(I) [Ag(COD) (HFA)] into a number of polyimides and then thermally curing those films at 300 °C for time intervals between 30 min and 3 h. Reflectivities of the films exhibited strong dependence on the infusion and cure conditions as well as on the type of polyimide used. The highest reflectivity of 67.1% was achieved with a silvered film prepared from 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (BTDA) and oxydianiline (ODA) infused at 5000 psi, 100 °C, for 30 min and cured for 1 h at 300 °C. Reflectivities of silvered surfaces of other polyimides investigated varied from 39% to 61%. A strong correlation between the presence of a ketonic group in the polyimide structure and the formation of mirror surfaces was detected.
synopsisModified polyimide films containing cobalt have been prepared by the addition of cobalt.@) chloride to a solution containing one of the diamines 4,4'-oxydianiline (ODA) or 4,4'diaminodiphenylsulfide ODs) and one of the dianhydrides 3.3, 4,4'-benzophenonetetracarboxylic dianhydride (BTDA) or 4,4'-bis(3,4-dicarboxyphenoxyMiphenylsulfide dianhydride (BDSDA) and characterized by thermal methods, UV-visible spectra, room-temperature direct-current electrical resistivity measurements, and X-ray photoelectron and Auger electron spectroecopy.A principal goal of this work was to establish if there was coordination of the potential donor atoms of the polyimide to cobalt. UV-visible spectra of the modifed polyamic acid solutions and polyimide films and a titration study of a model system do not show any appreciable coordination with either the polyamic acid or the polyimide; rather, the cobalt(I1) appears to be coordinated to the solvent, NJV-dhethylacetamide @MAC), as [C~@MAC),]~+, until the temperature is raised above 200°C. X-ray photoelectron spectra of films cured only to 200T alao do not show significant shifts in the binding energies of the potential donor atoms from those binding energies of the undoped polymers, confirming little direct coordination of the cobalt to atoms of the polyimide. Heating the filp to 3OOT in a forced-air oven causes the formation of a cobalt oxide layer on the air side of the polymer. Dired-current electrical resistivity measurements on this surface show a 104-108 reduction in resistivity due to this layer.
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