Abstract
Ultraviolet (UV) radiation poses significant risks to human health and interior materials, creating a demand for effective transparent shielding solutions. While organic polymer-based filters are widely used, they often suffer from poor weatherability and mechanical instability. This study aims to develop a durable, transparent, and hydrophobic UV-shielding coating using a methyltrimethoxysilane (MTMS) matrix reinforced with tungsten oxide (WO3) nanoparticles, specifically designed for scalable retrofitting on glass substrates. Nanocomposite coatings were prepared by dispersing WO3 nanoparticles into MTMS/ethanol solution. Four formulations were synthesized with WO3 loadings of 0, 6.25, 12.5, and 25 wt% relative to the precursor. The coatings were applied to glass slides using a facile sponge-coating technique. Characterization included Field Emission Scanning Electron Microscopy (FESEM) for morphology, X-ray Diffraction (XRD) for crystallinity and Fourier-Transform Infrared (FTIR) spectroscopy for chemical bonding. Optical performance was evaluated via ultraviolet-visible (UV-Vis) spectroscopy (200–900 nm) and surface wettability was assessed using water contact angle measurements. Mechanical durability was tested using the standard pencil hardness test before and after 48 hours of water immersion. XRD and FTIR analyses confirmed the successful covalent anchoring of crystalline WO3 nanoparticles into the siloxane network. FESEM revealed a crack-free surface with homogeneous nanoparticle dispersion. A direct trade-off between UV-shielding and visible transparency was quantified. The 25 wt% sample achieved the highest UV-shielding (81.08%) but suffered from low visible transparency (TVis = 50.44%). The 6.25 wt% formulation was identified as optimal, delivering 63.23% UV-shielding while maintaining high transparency (TVis = 76.32%), surpassing the architectural standard of 70%. All coatings maintained 9H pencil hardness even after water immersion, though hydrophobicity decreased slightly with higher WO3 loading due to surface hydroxyl groups. The MTMS-WO3 coatings demonstrate an excellent balance of optical clarity, UV protection and mechanical hardness compared to conventional soft-polymer films. The 6.25 wt% formulation is proposed as the optimal concentration for durable and transparent UV-shielding applications in architectural and automotive glazing.