The integration of inorganic nanoparticles into transparent polymers allows for the function-alization of plastics. Due to the small particle size, a high transmittance may be achieved even for high filler contents. However, a crucial point is to achieve integration of the particles inside the matrix without aggregation of the inorganic nanoparticles. Using in situ-polymerization, several optical functions can be integrated into nanocomposites. Manganese-doped ZnS nanoparticles show orange luminescence. Europium-doped YVO_(4) emits red light. An interesting feature is controlled photobleaching of the latter for patterning. Another potential application of inorganic nanoparticles is their use as color filters. Zinc oxide (ZnO) is an efficient UV filter with a strong absorption at 360 nm. Nanocomposites composed of ZnO and poly(butanediol monoacrylate) show a strong absorption in the UV-range but a high transparency in the visible. As compared to the pure polymer an increase in the elastic modulus is observed upon integration of the particles. BiOI nanoparticles show a pronounced quantum size effect allowing one to adjust the color of the pigment with the particle size from deep red via orange to a yellow or even colorless pigment. Effective adjustment of the particle size was achieved using a reverse microemulsion technique. Preliminary results indicate the accessibility of BiOI-nanocomposites as novel photochromic switching materials with a reversible color change between yellow and black upon UV irradiation.
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