Differences in nano structure on PET films formed with low-pressure and atmospheric pressure plasmas

At present, dielectric barrier discharge methods is commonly used for treatment of polymer films. Many works are reported on cleaning and adhesion improvement of them, and recently, roll-to-roll atmospheric pressure treatment is also available However, there are few reports on the detailed discussion on the nano-structure formation on the polymer surface. We have investigated differences between PET surface treatments with low-pressure and atmospheric-pressure plasmas. In the case of low-pressure oxygen-plasma treatment, we can obtain fine nano-structured roughness on the PET after the treatment. This brings about super hydrophilic feature on the surface, and super hydrophobic feature is available after forming hydrophobic self-assembled monolayer on it. In the case of atmospheric-pressure plasma treatment, we cannot obtain the fine roughness but broader roughness. This is considered to be due to a kind of ``loading effect.'' A possible method for preventing the loading effect is proposed.