Light-induced properties in polyimides containing side azobenzene groups

A series of new photosensitive polymers have been synthesized by polycondensation reaction of diamines containing azobenzene moieties with hexafluoroisopropylidene diplahalic anhydride or with a diacid chloride containing hexafluoroisopropylidene or dimethylsilane. These amorphous polymers have good solubility in organic solvents and good film forming properties. The irradiation of polymer films with linearly polarized UV-Vis light causes a reorientation of the azobenzene groups by angular-selective E/Z photoisomerization. Thus, optical anisotropy is induced in the initially isotropic films. The photoinduced dichroisin in the films has been measured and the results are discussed with respect to the polymer structure.