SYNTHESIS OF REFLECTIVE POLYIMIDE FILMS VIA IN-SITU SILVER(I) REDUCTION

Optically reflective polyimide films have been prepared by the incorpo ration of silver(I) acetate and hexafluoroacetylacetone into a dimethy lacetamide solution of the poly(amic acid) formed from 3,3',4,4'-benzo phenonetetracarboxylic acid dianhydride (BTDA) and 4,4'-oxydianiline ( 4,4'-ODA). Thermal curing of the silver(I)-containing poly(amic acid) leads to imidization with concomitant silver(I) reduction, yielding a reflective silver surface. The metallized BTDA/4,4'-ODA films retain t he essential mechanical properties of undoped films and have good ther mal stability particularly in nitrogen atmospheres. The surface and bu lk are not electrically conducting. Several additional soluble silver( I) additive systems were examined, all of which underwent thermal redu ction to metallic silver but gave widely varying degrees of reflectivi ty.