Water and oxygen permeability of silica thin films containing organic polymers coated on poly (ethylene terephtalate) substrate by the sol-gel method

Silica thin films containing organic polymers, such as poly(vinyl alcohol), poly(vinylpyrrolidone) or poly(vinyl acetate), were prepared on PET substr ates by the sol-gel method. Poly(vinyl alcohol) was found to be most effect ive to suppress the water permeability of PET substrates coated with the or ganic-inorganic composite films among the three. Under the optimal conditio n, the water permeability coefficient was about 40% of that of PET substrat es. The oxygen permeability coefficient was decreased with an increase in t he poly(vinyl alcohol) content in the composites and was about 10% of that of PET substrates when a large amount of poly(vinyl alcohol) was included i n the composites.