Preparation and characterization of TiO2 sols and their UV-cured hybrid thin films on plastic substrates

In this research, TiO2 sols were synthesized via a sol–gel reaction at room temperature followed by heating under reflux. Hybrid thin films were prepared using the TiO2 sols and dipentaerythritol hexacrylate on poly(methyl methacrylate) substrates via spin coating followed by UV-curing. The images of transmission electron microscopy (TEM) and results of dynamic light scattering (DSL) showed that some originally synthesized TiO2 nanoparticles aggregated while many small-sized (~5 nm) TiO2 nanoparticles still existed after reflux heating. The synthesized TiO2 sols showed poor photocatalytic ability, which might avoid degradation of organic moieties in the hybrids. The refractive indices of the hybrid thin films were increased from 1.66 to 1.82 while the water contact angles on the thin films were increased from 70.2° to 87.7° with the increment of TiO2 content. Increasing the heating time of the TiO2 sol resulted in an increase in the refractive index and contact angle.