SUPERCRITICAL-FLUID INFUSION OF SILVER INTO POLYIMIDE FILMS OF VARYING CHEMICAL-COMPOSITION

Polyimides can be infused with silver complexes by the use of supercri tical fluids. Highly reflective polyimide films were formed by infusin g ne-1,1,1,5,5,5-hexafluoroacetylacetonato)silver(I) [Ag(COD)(HFA)] in to a number of polyimides and then thermally curing those films at 300 degrees C for time intervals between 30 min and 3 h. Reflectivities o f the films exhibited strong dependence on the infusion and cure condi tions as well as on the type of polyimide used, The highest reflectivi ty 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 degrees C, for 30 min and cured for 1 h at 300 degrees C. Reflectivities of silvered surfaces of other polyimi des investigated varied from 39% to 61%. A strong correlation between the presence of a ketonic group in the polyimide structure and the for mation of mirror surfaces was detected.