Preparation of silica-based hybrid materials coated on polypropylene film

In this study, silica-based organic–inorganic hybrid coating materials were prepared by the sol–gel method. Tertaethoxysilane and polyvinyl alcohol were used as the inorganic and organic compounds, respectively. The substrate polypropylene film surface was modified by corona-plasma treatment to provide appropriate adhesion between the coating material and the polymer base film. A silane.coupling agent of vinyltriethoxysilane was also used to improve the adhesion between the base film and the coated layer. The effects of vinyltriethoxysilane in the hybrid materials were investigated using Fourier transform infrared analyses and X-ray diffraction. The vinyl group of vinyltriethoxysilane increased the hydrophobicity of the hybrid materials. The polypropylene films coated with the hybrid materials were characterized by examining their morphology, optical transparency and oxygen permeability. The results showed that the formation of hydrogen bonds between polyvinyl alcohol and the other compounds affected the microstructure of the coating solution and the final oxygen permeation property. Further, although the presence ofvinyltriethoxysilane in the hybrid coating solution could improve adhesion between the coated layer and the polymer base film, it deteriorates the effectiveness of the barrier to prevent of oxygen permeation through the coated film. However, the coated film maintained visible transparency and even enhanced the transmission of long wavelength visible-light owing to refractive index matching.