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Häckel, Michael ; Kador, Lothar ; Kropp, Daniela ; Frenz, Carsten ; Schmidt, Hans-Werner:
Holographic Gratings in Diblock Copolymers with Azobenzene and Mesogenic Side Groups in the Photoaddressable Dispersed Phase.
In: Advanced Functional Materials.
Bd. 15
(2005)
Heft 10
.
- S. 1722-1727.
ISSN 1616-3028
DOI: https://doi.org/10.1002/adfm.200500158
Abstract
Diblock copolymers, consisting of a photoaddressable mesogen-containing dispersed phase and a polystyrene matrix, have been synthesized and characterized as holographic data storage materials. The photoaddressable phase contains p-methoxy-substituted azobenzene side groups and benzoylbiphenyl mesogenic side groups in a statistical distribution. Three-ring mesogenic groups in combination with photoaddressable azobenzene side groups have been introduced for the first time in block copolymers in order to increase the local refractive-index difference between illuminated and non-illuminated volume elements, as well as to improve the stability of the orientation, while, at the same time, decreasing the optical density. To this end, a series of block copolymers with different azobenzene/mesogen ratios have been synthesized. The light-induced reorientation dynamics of the chromophores and mesogens and the long-term stability of the orientation have been studied with volume holographic measurements. A remarkable increase in stability of the holographic gratings has been achieved.