Investigation of crystallinity effects on the surface of oxygen plasma treated poly(ethylene terephthalate)

Plasma treatment is very useful method to make hydrophobic polymer surface to hydrophilic surface for improving wettability and adhesion properties without affecting bulk properties. However, since the mobility of polymer chains enables polymer surface to respond to interfacial force and to adapt their surface chemical structure to their environment, polymer shows hydrophobic recovery after plasma treatment in air. By rotational and translational motions of chains and chain segments, the surface composition can change in order to minimize the interfacial free energy between the polymer surface and environment. The degree of crystallinity in plasma processing has influences on surface topography, formation of new functional groups, etching and hydrophobic recovery (ageing). Therefore, the polymer crystallinity should be taken into consideration when optimizing plasma treatment processes. In order to investigate the role of polymer crystallinity, we reviewed oxygen plasma treatment experiments on amorphous and semicrystalline poly(ethylene terephthalate) (PET) polymers.