Surface modification of ethylene-vinyl alcohol copolymer treated with plasma source ion implantation

The plasma source ion implantation technique was applied to modify the surface of ethylene-vinyl alcohol (EVOH) film using various working gases. The effects of the treated films were observed on the adhesion efficiency and physical properties. The hydrophobic properties of EVOH films were greatly enhanced after tetrafluoromethane-plasma source ion implantation (PSII) treatment. On the other hand, the higher hydrophilic properties of EVOH films increased after oxygen-PSII treatment. The results of X-ray photoelectron spectroscopy showed that the improved hydrophobic or hydrophilic properties of the film were closely related to the formation of fluorine-containing functional groups (i.e., CF, CF₂, and CF₃) or oxygen-containing functional groups (i.e., CAO, C=O) on the modified surface. According to the result observed by atomic force microscopy, the surface roughness was not influenced on the change of contact angle. Both the peel strength and oxygen barrier property were improved in the case of CF₄+O ₂-PSII-treated EVOH films. As a function of aging time, the properties of modified EVOH surfaces were maintained after PSII treatment using CF₄ and O₂ at the energy level of -5 kV for 1 min. When using PSII treatment, the properties of the EVOH surface were controlled by working gas and treatment conditions.