Preparation of Oleyl Phosphate‐Modified TiO 2 /Poly(methyl methacrylate) Hybrid Thin Films for Investigation of Their Optical Properties

TiO 2 nanoparticles (NPs) modified with oleyl phosphate were synthesized through stable Ti–O–P bonds and were utilized to prepare poly(methyl methacrylate)‐ (PMMA‐) based hybrid thin films via the ex situ route for investigation of their optical properties. After surface modification of TiO 2 NPs with oleyl phosphate, IR and 13 C CP/MAS NMR spectroscopy showed the presence of oleyl groups. The solid‐state 31 P MAS NMR spectrum of the product revealed that the signal due to oleyl phosphate (OP) shifted upon reaction, indicating formation of covalent Ti–O–P bonds. The modified TiO 2 NPs could be homogeneously dispersed in toluene, and the median size was 16.1 nm, which is likely to be sufficient to suppress Rayleigh scattering effectively. The TEM images of TiO 2 /PMMA hybrid thin films also showed a homogeneous dispersion of TiO 2 NPs, and they exhibited excellent optical transparency even though the TiO 2 content was 20 vol%. The refractive indices of the OP‐modified TiO 2 /PMMA hybrid thin films changed higher with increases in TiO 2 volume fraction, and the hybrid thin film with 20 vol% of TiO 2 showed the highest refractive index ( n = 1.86).