Transparent hydrophobic fluorocarbon coatings fabricated on regenerated cellulose films by RF magnetron sputtering

A series of novel transparent hydrophobic regenerated cellulose (RC) films were coated with a fluorocarbon polymer by radio frequency magnetron sputtering. The effect of sputtering power and pressure on the surface morphology, chemical composition, contact angle and visible light transmittance of the coated films were investigated by atomic force microscopy, X-ray photoelectron spectroscopy, contact angles and ultraviolet-visible spectroscopy. The surface roughness increased as the sputtering power and pressure increased. The fluorocarbon coatings contained four components: -CF3, -CF2-, -CF- and -C-. The relative proportions of the saturated components significantly affected the hydrophobicity of the coatings. After applying a fluorocarbon coating, the static contact angle of the coatings was greater than 90 degrees, and the substrate RC film was transformed from hydrophilic to hydrophobic. The visible light transmittance was greater than 80% when the roughness of the coating was less than 100 nm. The optimal sputtering conditions used a power between 80 and 150W, and pressure between 1.0 and 3.0 Pa.