Formation of Cu-based nanoparticles during imidization of PAA into PI in the various environments

A new method has been recently developed to fabricate highly dense nano-sized Cu2O particles in a polyimide film. Cu2O nanoparticles formed from the reaction of polyamic acid with a metal thin film and subsequent curing. In this paper, we report that both Cu2O and metallic Cu nanoparticles can be formed depending on the curing environment. When the N2 flow rate was very low during curing, Cu2O nanoparticles formed. Meanwhile, Cu nanocrystals were formed during curing in the N2 atmosphere employing a high flow rate or in a vacuum. Optical absorption spectra showed the surface plasmon resonance peak from metallic Cu nanoparticles at around 580–600 nm. Our results showed that Cu nanoparticles as well as Cu oxide nanoparticles can be formed by controlling the curing environment.