Ultrastable Waterborne Nanocomposite Coating of Polyurethane and Zirconia Nanoparticles To Avoid Rainbow Effect on Polyester-Based Superficial Hardening Films

Transparent nanocomposites constructed by adding ultrasmall inorganic nanoparticles into an organic polymer matrix have been a new paradigm for preparing functional films for various optical components. Herein, aiming to avoid the negative influences of the rainbow effect on polyester film optoelectronic devices, a transparent nanocomposite of waterborne polyurethane (WPU) and ZrO2 nanoparticles is reported. The water-dispersible nanoparticles of ZrO2 modified with citric acid (CA) are first synthesized, which ensures homogeneous blending of ZrO2 nanoparticles and WPU emulsions. The ZrO2@CA nanoparticles can be well dispersed in the alkaline aqueous solution with a solid content of 5 wt %. The ZrO2/WPU hybrid films exhibit high transparency of visible light and the products of polyester-based hard coating films without rainbow effect are successfully prepared by using the ZrO2/WPU hybrid films as a functional layer for interference cancellation. This work demonstrates an efficient approach for developing water-dispersible ultrasmall ZrO2 nanoparticles and nanoparticle-derived transparent nanocomposites for advanced applications in optics.