Preparation of Oleyl Phosphate-Modified TiO2/Poly(methyl methacrylate) Hybrid Thin Films for Investigation of Their Optical Properties

Abstract

TiO2nanoparticles (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 theex situroute for investigation of their optical properties. After surface modification of TiO2NPs with oleyl phosphate, IR and13C CP/MAS NMR spectroscopy showed the presence of oleyl groups. The solid-state31P 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 TiO2NPs 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 TiO2/PMMA hybrid thin films also showed a homogeneous dispersion of TiO2NPs, and they exhibited excellent optical transparency even though the TiO2content was 20 vol%. The refractive indices of the OP-modified TiO2/PMMA hybrid thin films changed higher with increases in TiO2volume fraction, and the hybrid thin film with 20 vol% of TiO2showed the highest refractive index (n = 1.86).