Conditions leading to the formation of polymer thin layers with densely dispersed organic dyes using the "vapor transportation method" with vacuum technique

The "vapor transportation method" with vacuum technique, developed previously in our laboratory, was used to form polymer thin layers with densely dispersed photochromic dyes on polystyrene (PS), poly(methyl methacrylate) (PMMA), and polycarbonate (PC) substrates. The organic photochromic dye cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethane (CMTE) was used, and the rate of formation of the CMTE-containing layer was as follows: PS > PC > PMMA. These observations are important for application of the present method to the formation of organic memory media for optical recording etc. These results also indicate that the formation rate is dependent on not only the chemical composition and the structure of the polymer substrate, but also on the treatment temperature. Optical density (OD) measurements of the CMTE-dispersed thin polymer films showed maximum values near the glass transition temperature (TB) with increases in temperature of film formation. The T-g values of CMTE-dispersed polymers decreased rapidly after CMTE-dispersal into the polymer matrices; indicating that T-g values of the polymers are important parameters for investigation of the mechanism of formation of CMTE-dispersed layers on polymer substrates using the present method.