The quantitative effect of silica nanoparticles on optical properties of thin solid silica UV-cured films

• Silica UV-cured films were prepared by dispersions of silica and acrylate monomer.
• Matching refractive indices in a colloidal system provide the dispersion stability.
• The effect of silica nanoparticles on optical properties of the films was studied.
• Total transmittance of all films is similar to that of the bare glass.
• The diffuse transmittance of the films depends on the amount of the particles.

A thin solid silica UV-cured film was prepared by coating the dispersion of commercial silica nanoparticles in a UV-curable acrylate monomer on a glass substrate using a bar coater. The silica UV-curable acrylate resin was stored for 24 h in the dark for film formation and then transformed into the thin solid silica UV-cured films upon exposure to UV light at the wavelength of 254 nm for 5 min at ambient temperature. The amount of silica nanoparticles in the UV-cured films was varied from 1 to 30 vol.% and then the optical properties of the coated glass were compared with the bare glass. The result revealed that the total transmittance of all the films is insignificantly different when the amount of silica nanoparticles increases. The total transmittance of all the coated glasses is similar to that of the bare glass indicating the transparency of the film. Although the total transmittance of the films is independent of the amount of particles, the improved diffuse transmittance of the films is obtained as the amount of particles increased. This is due to the enhanced multiple scattering that occurs in the film. The increased amount of silica nanoparticles also leads to the formation of the aggregated particles with a larger size and homogeneous dispersion as evidenced from the FE-SEM images. These indicated that the amount and distribution of the silica nanoparticles strongly affect the improved optical properties of the thin solid silica UV-cured film.