Highly-crystalline zirconia (ZrO(2)) nanoparticle was functionalized with 3-(N-aminoethyl) aminopropyl-trimethoxysilane (AAPTMS) and dispersed in water at primary particle size level under basic condition (pH13-14). The aqueous ZrO(2) nanoparticle dispersion was cast on a polycarbonate substrate with 1,4-butanediol digylcidyl ether as a cross-linker. Nanoparticle films with as high as 81 wt.% of ZrO(2) were obtained through heating the cast dispersion at 120 degrees C. which are highly transparent. The refractive index ranges from 1.70 to 1.77 at wavelength of 632 nm with the decrease of the amount of AAPTMS attached to ZrO(2) nanoparticles. Nanoindentation tests show that the hardness of the film reaches 1 7 GPa. In addition, both tape abrasion and nanoscratch tests reveal that the films exhibit prominent scratch resistant performance (C) 2010 Elsevier B.V. All rights reserved