Investigation of the influence of low-pressure plasma on PET to improve layer adhesion between PET and ALD multilayers

The paper shows the influence of low-pressure plasma on polyethylene terephthalate (PET) to achieve improved layer adhesion between PET and ALD multilayers. The literature describes a relationship between functional groups that are incorporated into the polymer surface and better layer adhesion. In this work, the relative number of functional groups after treatment on the surface of PET was measured by the surface energy. The PET film Hostaphan® RNK was exposed to oxygen and argon plasma with varying treatment times. Subsequently, the surface energy was determined via the contact angle measurement. The investigations have shown that with increasing treatment time in the oxygen plasma, an increasing surface energy is associated, which is due to the increased incorporation of functional groups, such as hydroxy groups. Furthermore, the results have confirmed the thesis that if the plasma treatment is too long, oxidation takes place on the polymer surface and thus the surface energy decreases. Another aspect that has emerged in the results of the study is the subordinate role of the power of the plasma. Since the study has not proven the connection between a good layer adhesion, of ALD multilayers on PET, and a high surface energy, this work should serve as an indication for the investigation of this thesis