Preparation and characterization of high-refractive-index polymer/inorganic hybrid films containing TiO2 nanoparticles prepared by 4-aminobenzoic acid

In this study we used 4-aminobenzoic acid (4ABA) as the chelating ligand to synthesize anatase TiO2 nanoparticles (NPs) in an aqueous solution. The chelating behaviors of 4ABA with respect to TiO2 NPs were evaluated by infrared spectroscopy, zeta potential analysis, x-ray photoelectron survey spectra, and differential scanning calorimetry. The pre-made TiO2 NPs were incorporated into epoxy resin with various NP contents to fabricate high-refractive-index hybrid films at a low film-forming temperature. We found that the hybrid films featuring TiO2 NPs prepared by 4ABA had higher refractive indices than those by acetic acid—a traditional chelating ligand. The difference can reach to 0.044 at 80% NP content. We suspect that the increase in refractive indices may arise from the fact that 4ABA features a higher refractive index and less demand due to the higher coordinating stability.