Synthesis of silsesquioxanes having photochromic dithienylethene pendant groups

Silsesquioxanes having 1-(2-methoxy-1-benzothiophen-3-yl)-2- [5-(4-butylphe nyl)-2, 4-dimethylthiophen-3-yl]perfluorocyclopentenes as the pendant group s were synthesized. Photochemical conversion from the open-ring to the clos ed-ring forms of the dithienylethenes increases when the methyl group at 2- position of the benzothiophene ring is replaced by a methoxy group. The con version is dependent on the content of dithienylethene in the polymer chain . No appreciable difference in the photochemical conversion was observed be low and above the glass transition temperature (T-g) of the polymer films. The activation energies of coloration and bleach processes were obtained to be 0-1 and 1-3 kcal/mol, respectively.