Highly reflective polyimide films created by supercritical fluid infusion of a silver additive

Supercritical fluid infusion of a silver-containing additive [1,5-cyclooctadiene silver(I)-1,1,1,5,5,5-hexafluoroacetylacetonate] into a fully cured polyimide was achieved with moderately high-density carbon dioxide at 110°C for the first time. The polyimide was derived from 4,4′-oxydianiline and 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride. After infusion for approximately 60 min, the resulting film was then recured at 300°C in air. During this time, a silver mirror formed on both film surfaces. The nature of the silver and its distribution within the film and on the film surface were established via microscopy and surface analysis techniques.