Effect of the RF-discharge plasma treatment of thin polyimide films on water diffusion

Abstract

The effects of the treatment of thin polyimide films of different thickness (2-7.5 µ m), which were prepared from poly(amic acid) solutions, in a radiofrequency-discharge plasma on the diffusion of water and the permittivity were studied. It was found that the diffusion coefficients of water in the films increased with film thickness. The increase of the diffusion coefficients by a factor of 4-24 and an increase in the permittivity by a factor of 1.5-2 after the action of an RF discharge on the films was explained by an increase in the amount of polar groups and the formation of an excess negative charge, which was injected from the plasma, in the bulk of the films.