Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

Characterization and photoinduced properties of photochromic polymers. 1. Polyesterimides with 4-amino 4'-nitro azobenzene moieties

: Schab-Balcerzak, E.; Sapich, B.; Stumpe, J.; Sobolewska, A.; Miniewicz, A.

e-Polymers. Online journal (2006), No.21, 17 pp.
ISSN: 1618-7229
Journal Article
Fraunhofer IAP ()

Novel photochromic polyesterimides (PEIs) with two different types of azobenzene units as side groups have been synthesized from 2,2'-{4-[(4-nitrophenyl)- azo} phenyl] iminobis( ethyl benzene-1,2-dicarboxylic acid anhydride-4-carboxylate) and diamines:2,4- diamino-4'-methylazobenzene and 2,4-diamino-4'( trifluoromethoxy) azobenzene. An analogous polyesterimide with one azobenzene group based on 1,3-phenylendiamine has been prepared to compare with these PEIs. Molecular structural characterization for these polymers has been achieved by FTIR, H-1 NMR and UV-Vis spectroscopy. These amorphous polyesterimides are thermally stable up to 260 degrees C as follows from the thermogravimetric analysis (TGA). The glass transition temperatures (T-g) for the resulting polyimides have been determined from DSC thermograms and are in the range of 141- 210 degrees C. The irradiation with linearly polarized light of an Ar+ laser results in the induction of optical anisotropy within the initially isotropic films. Light induced optical anisotropy in polymer films has been studied by examining the value of generated dichroism using Ar+ laser (lambda = 488 nm) and by holographic polarization grating recording performed at lambda = 514.5 nm. The value of photoinduced dichroism is in the range of 0.15-0.26. The induction of dichroism and kinetics of grating inscription have been investigated in relation to the presence of the second type of azobenzene group in the polymer and its substitution.