Hydrophilic/hydrophobic surface of Al2O3 thin films grown by thermal and plasma-enhanced atomic layer deposition on plasticized polyvinyl chloride (PVC)

• The Al2O3 thin films were deposited on PVC by T-ALD and PE-ALD techniques.
• The PE-ALD Al2O3 films exhibited a hydrophilic surface.
• The T-ALD Al2O3 films exhibited a hydrophobic surface.
• The carbon residue affects the hydrophilicity/hydrophobicity of the Al2O3 films.
• The surface properties of the Al2O3 thin films can be modified by the ALD conditions.

Thermal ALD (T-ALD) and plasma-enhanced ALD (PE-ALD) processes were employed to prepare the Al2O3 thin films on plasticized polyvinyl chloride (PVC) surfaces at a low deposition temperature of 80 °C. The water contact angle test shows that the T-ALD Al2O3 films exhibited a hydrophobic surface, while the PE-ALD Al2O3 films were hydrophilic. The difference in the surface hydrophobicity is attributed to the carbon residue in Al2O3 films, as revealed by the X-ray photoelectron and Fourier transform infrared spectroscopies. The trend of hydrophobicity follows with the evolution of surface roughness of the T-Al2O3 films, indicating that the surface roughness contributed to the hydrophobicity as predicted by the Wenzel's mode. The result indicates that the surface hydrophilicity/hydrophobicity of the Al2O3 thin films can be modified and controlled by the deposition conditions of the ALD process.