The incorporation of inorganic particles into polymers allows to integrate new functions inside the polymer matrices, and for transparent plastics, modification of the matrix by dispersing a second inorganic components into the polymer usually results in a significant loss of transparency due to scattering from large particle or agglomerates. In the microemulsion technique, water droplets 10-20 nm in diameter are used as nanoreactors for the generation of inorganic particles. The integration of luminescent nanoparticles, such as doped semiconducting sulfides into transparent polymers produces luminescent hybrid materials. Inorganic semiconducting oxides such as ZnO are effective UV-absorbers as its band gap could be adjusted with the size of particles.