Thermal stability of merocyanine form in spiropyran/silica composite film

Three types of spiropyran derivatives introduced octadecyl group (SP18), hydroxyl group (SPOH) and carboxyl group (SPCOOH) were synthesized and were dispersed into various matrices such as chloroform solvent, polymethylmetacrylate (PMMA)/acetone solution and poly(perhydrosilazane) (PSz)/m-xylene solution. Thermal stability of photomerocyanine isomer (PMC-form) in spiropyran derivatives dispersed in silica composite film was studied. Intensity at λmax of PMC-form in silica composite film keeps at initial values in long time except for SP18. PMC-form of SPOH and SPCOOH forms intermolecular hydrogen bonding between hydroxyl or carboxyl group and oxygen atom in silica matrix. Therefore, PMC-form of SPOH and SPCOOH in silica composite film is stabilized dramatically.