High refractive index PU-acrylate/ZrO₂ transparent nanocomposite

This study used methacrylic acid as surface modifier to facilitate the homogeneous dispersion of n-ZrO2 into polymer. Nanocrystals of ZrO₂ modified with methacrylic acid were first tested for it dispersibility in selected organic solvents. It was found that n-ZrO₂ modified with methacrylic acid was able to disperse in solvents such as ,MeOH,EtOH, THF, Benzen and CHCl₃, Consequently, the methacrylic acid modified n-ZrO₂ was selected to blend with acrylate for further study. The blending of modified n-ZrO₂ and urethane-acrylate, as well as the initiator was accomplished in THF solvent. After the removal of solvent, the transparent composite was UV-cured into a highly transparent film. The refractive index of the composite increased from the value of 1.51 for the original resin to 1.63 and the hardness increased from 170 to 470 MPa. when 53 wt% of n-ZrO₂ was added, and the transparency remains at 97.1% for a film thickness of 25 μm.