Protavic Sg Fp Sol-Gels For Thin Film Coating With Fast Photochromic Response (In French)

Existing photochromic glasses become dark in a couple of minutes, and get back to the original colour in about the same time. Sol-gel chemistry allows the preparation of hybrid inorganic/organic material. The organic part can be adjusted to modify the hydrophobicity/hydrophilicity of the internal matrix of the material. Some organic photochromic molecules have the properties to have their ionisation status modified while they change colour. By an appropriate formulation of the sol-gel solution it has been possible to get a good solubility of the organic photochromic molecule in the solution ad in the matrix. Moreover, the time to coloration or discoloration has been drastically reduced down to a couple of seconds.