Synthesis of silsesquioxanes having photochromic dithienylethene pendant groups

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