Low-temperature atomic layer deposition of Al₂O₃ on blown polyethylene films with plasma-treated surfaces

In this study, a layer of Al₂O₃ was deposited on blown polyethylene films by atomic layer deposition (ALD) at low temperatures, and the surface characteristics of these Al₂O₃-coated blown polyethylene films were analyzed. In order to examine the effects of the plasma treatment of the surfaces of the blown polyethylene films on the properties of the films, both untreated and plasma-treated film samples were prepared under various processing conditions. The surface characteristics of the samples were determined by x-ray photoelectron spectroscopy, as well as by measuring their surface contact angles. It was confirmed that the surfaces of the plasma-treated samples contained a hydroxyl group, which helped the precursor and the polyethylene substrate to bind. ALD of Al₂O ₃ was performed through sequential exposures to trimethylaluminum and H₂O at 60 °C. The surface morphologies of the Al ₂O₃-coated blown polyethylene films were observed using atomic force microscopy and scanning electron microscopy/energy-dispersive x-ray spectroscopy. Further, it was confirmed that after ALD, the surface of the plasma-treated film was covered with alumina grains more uniformly than was the case for the surface of the untreated polymer film. It was also confirmed via the focused ion beam technique that the layer Al₂O₃ conformed to the surface of the blown polyethylene film.