| dc.description.abstract |
Superhydrophilic hard coatings are frequently applied on plastic substrate as a protective layer. The coatings have been recently widely fabricated by sol-gel processes. Here, a bilayer hard coatings with superhydrophilic performance was developed on polyethylene terephthalate (PET) substrate using modified sol-gel processes. The bottom coating, UV curable hybrid hard coating, is an organic/inorganic composite comprising surface-modified silica with acrylic groups embedded in pentaerythritol tetraacrylate (PETTA) cross-linked network to provide a mechanical support. The upper coating was modified using superhydrophilic nanoparticles, which synthesized by tetraethoxysilane (TEOS) in base catalyst. Various methods, e.g., UV/VIS spectrophotometer, atomic force microscopy (AFM), water contact angle, pencil hardness test, adhesion test and abrasion-resistant test, anti-fogging test, soaking test, durability test were employed to characterize the film performance. The results indicated that the amount of PETTA was deeply affect hybrid hard coatings characteristics. Especially, the hardness of hybrid hard coatings significantly improved with the addition of PETTA, due to the PETTA has four reaction functional groups. The optimal bilayer superhydrophilic hard coatings has not only excellent hardness (4H) but also superior flexibility. It also exhibited that superhydrophilic properties (WCA<10°) were effectively improved after applying the superhydrophilic nanoparticles on the hybrid hard coatings surface. The average transmittance (400-700 nm) of the coatings also increased by applying the nanoparticles layer efficiently. It demonstrated that the bilayer hybrid hard coatings can be applied on many industries. | en_US |