Surface modification of TiO2 nanoparticles doped in photocured resins for the high refractive index optical waveguide

Abstract

To improve the refractive index of the nanoimprinting resin and the dispersion of TiO₂ nanoparticles in propylene glycol methyl ether acetate (PGMEA), silane coupling agent KH570 and 2-Ethylhexyl methacrylate (EHMA) were used to modify the surface of TiO₂ nanoparticles. The results show that KH570/EHMA modified TiO₂ nanoparticles have good dispersion ability in organic solvents and can effectively improve the surface hydrophobicity, particle uniformity, and optical properties of acrylate polymer/TiO₂ nanocomposite coatings. At the same time, the optimal pH condition of KH570 for TiO₂ reaction was determined. After doping with modified TiO₂, the refractive index of the nanoimprinting resin increased from 1.57 to 1.84 (@532 nm) when the solid content was 40 %. Nano-grating optical waveguide with high refractive index was successfully prepared. The diffraction efficiency of the grating is significantly improved.