Gas barrier properties of hydrogenated amorphous carbon films coated on polyethylene terephthalate by plasma polymerization in argon/n-hexane gas mixture

• a-C:H films were prepared by plasma polymerization in Ar/n-hexane atmosphere.
• Barrier properties of coatings are dependent on their density and thickness.
• Highest barrier properties were observed for films with thickness 15 nm.

Hydrogenated amorphous carbon thin films were deposited by RF plasma polymerization in argon/n-hexane gas mixture on polyethylene terephthalate (PET) foils. It was found that such deposited films may significantly improve the barrier properties of PET. It was demonstrated that the principal parameter that influences barrier properties of such deposited films towards oxygen and water vapor is the density of the coatings. Moreover, it was shown that for achieving good barrier properties it is advantageous to deposit coatings with very low thickness. According to the presented results, optimal thickness of the coating should not be higher than several tens of nm.