Improvement of hydrophobic properties of polymer surfaces by plasma source ion implantation

The industrial use of linear low density polyethylene (LLDPE) and poly(ethylene terephthalate) (PET) films are limited because of undesirable properties of the polymer surface, for example, poor adhesion, printability, and gas barrier properties. The plasma source ion implantation (PSII) technique with CF4 gas was used for LLDPE and PET films to improve the surface hydrophobic properties. Their treated surfaces were characterized to understand the mechanism of modification processes by X-ray Photoelectron Spectrometry (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS). Variables examined in implantation were ion energy (0–10 keV), treatment time, and ion species. The modified surfaces of LLDPE and PET were also analyzed to check the relevance of the modification and aging on the polymer surface. PSII treated polymers were found to have more hydrophobic properties than traditional plasma treated samples. The hydrophobic properties of polymer films were greatly enhanced after CF4-PSII treatment as evidenced by an increased contact angle and an decreased surface energy. XPS and TOF-SIMS data provided the evidence that hydrophobic properties of the modified polymer surfaces are related to the fluorine-containing functional groups, especially CF2 and CF3 groups.