Hybrid pigments via sol-gel processing

The incorporation of organic dyes into inorganic and hybrid sol-gel derived materials is a valuable method for the fabrication of colored layers for o ptical applications like filters, solar energy conversion, non-linear optic al devices, and active laser media. There have been clear hints for photoch emical stabilization of the organic dyes, therefore, our aim was to investi gate the light stability of organic dyes within hybrid solids. Besides the traditional way of doping sol-gel coatings with dyestuffs, they were also c ovalently attached to the hybrid matrix and pigments were produced by spray -drying processes. The resulting spherical powders were investigated with respect to their mor phological, structural and photochemical properties. The results show that uniformly shaped and colored hybrid pigments can be synthesized. The spectr oscopic studies demonstrate the fixation of the dye to the matrix and the h igh degree of crosslinking achieved in the composite. Additionally, the hyb rid pigments drastically improve the resistance of the dye against bleeding from thermoplastic polymers. Furthermore, a higher photochemical stability of the dye is observed within the hybrid matrix compared to a solution, an d purely organic or inorganic solid hosts.