Enhanced physical properties of UV-cured transparent PUA coating based on a “nanoparticle take root on surface” strategy by dual-functionalized nano-silica

Inspired by the rooting of seeds, dual-functionalized silica nanoparticles (FM x SiO 2 ) with both perfluorooctyl (F) and methacrylate (M) groups were prepared and used to develop a UV-cured polyurethane acrylate (PUA) hybrid coating having a unique balance of high hardness, excellent transparency, and superior anti-smudge performance. The FM x SiO 2 nanoparticles with various F/M ratios (x) were synthesized via a controlled sol-gel process and co-modified by changing the volume ratios of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS-17) to 3-methacryloxypropyltrimethoxysilane (MPTS). The methacrylate groups (from MPTS) enabled covalent crosslinking with the polymer matrix during photopolymerization, while the perfluorodecyl groups (from FAS-17) facilitated nanoparticle migration to the surface, forming a low surface energy layer. The optimized hybrid coating with 5 wt% FM 5 SiO 2 exhibited outstanding mechanical and surface properties, including a pencil hardness of 9H, a Young's modulus of 42.7 GPa, and visible light transmittance of up to 97%. Furthermore, the surface energy was significantly reduced to 25.8 mJ·m −2 , endowing the coating with excellent water and oil repellency, scratch resistance, and self-cleaning behavior. These excellent physical properties were attributed to FM x SiO 2 NPs with efficient surface migration and uniform dispersion having strong interfacial bonding with PUA. This study provides a synergistic design strategy that combines nanoscale reinforcement and surface-energy regulation to fabricate transparent, mechanically robust, and self-cleaning UV-curable coatings.