Light diffusing films fabricated by strawberry-like PMMA/SiO2 composite microspheres for LED application

This paper presents a facile method to fabricate volumetric light diffusing films with high transmittance and haze simultaneously by mimicking the micro- and nanostructure of compound eyes. Strawberry-like polymethyl methacrylate/SiO 2 composite microspheres were first prepared via the electrostatic attraction between positively charged PMMA spheres and negatively charged SiO 2 nanoparticles , and further blended with polyacrylate latex to produce light diffusing coatings. A novel light diffusing film with hemispherical surface was built by casting the light diffusing coatings on optical-grade PET film. Effects of the sizes of PMMA spheres and SiO 2 nanoparticles on the optical properties of light diffusing film were investigated by a haze meter and application on a LED lamp. The best result (transmittance 94.6% and haze 84.2%) was achieved for the strawberry-like composite microspheres based on 1   μm PMMA spheres and 50   nm SiO 2 nanoparticles. The light-diffusing mechanism of the strawberry-like microspheres in the film was discussed.