Waterborne Hydrophobic Hard Coatings Based on Fluorinated Silica with Maintained Optical Transparency for Automotive Display Films

Abstract A waterborne fluorinated silica nanoemulsion was developed as a multifunctional additive for transparent automotive display coatings. Aqueous colloidal silica was first functionalized with γ-methacryloxypropyltrimethoxysilane (γ-MPS), followed by KPS-initiated polymerization of dodecafluoroheptyl methacrylate (DFMA). The modified silica was blended with a waterborne acrylate emulsion and wet-coated onto PC/PMMA films. Solid-state 29Si NMR confirmed γ-MPS condensation through the formation of T2 and T3 species, while XPS verified the introduction of DFMA-derived fluorinated groups. The optimized coating exhibited a water contact angle of approximately 107°, pencil hardness up to 3H, and visible-light transmittance of about 90% or higher. Fingerprint contamination and wiping tests further demonstrated improved easy-clean performance; the haze of the coated film decreased to approximately 0.99% after only two wiping steps, compared with 1.52% for bare PC/PMMA under the same conditions. After 100 steel-wool abrasion cycles, the transmittance change was limited to 0.4%, compared with 0.9% for the unfilled acrylic coating and 2.7% for bare PC/PMMA. SEM analysis confirmed reduced scratching and surface deformation. These results demonstrate a promising waterborne route to transparent, hydrophobic, easy-clean, and abrasion-resistant coatings for automotive display applications.