Synthesis of Cu or Cu2O-polyimide nanocomposites using Cu powders and their optical properties

Abstract

Nanocomposites consisting of Cu or Cu 2 O nanoparticles in various polyimide (PI) films were successfully prepared using polyamic acid (PAA) and Cu powders. Cu powders were dissolved into PAA solutions, and the solutions were spin-coated onto the substrates. Cu or Cu 2 O nanoparticles were formed in PI film by curing in a reducing or inert atmosphere, respectively. The Cu nanoparticles were transformed to Cu 2 O nanoparticles by post-heat treatment in an oxidizing atmosphere after curing in a reducing atmosphere. Transmission electron microscopy showed that uniform, round Cu 2 O nanoparticles 6.0 nm in diameter were dispersed in the PI film by post-heat treatment. The addition of Cu 2 O nanoparticles in the 4,4′-(hexafluoroisopropylidene)diphthalic anhydride-4,4′-oxydianiline (6FDA-ODA) PI film enhanced the refractive index of the 6FDA-ODA PI film from 1.60 to 1.72 at 633 nm, and the transparency of the nanocomposite film was about 70?90% in the visible region and remained around 90% beyond 550 nm.