Photoinduced Crosslinking of Distyrylbenzene Containing Blockcopolymers for Manufacture of New Photoalignment Layers.

摘要

1. Photooriented polymer films have received increased interest for the alignment of liquid crystals; 2. Photoalignment layers obtained by photochemical reactions reduce the disadvantages, i.e., dust formation and static electricity build up during the rubbing process, of commercially used rubbed polyimide films. 3. Particularly surface effects are crucial for the alignment of liquid crystals controlled by photoactive polymeric films. 4. Azobenzene, coumarin and cinnamate containing polymers have been already investigated in detail; 5. In the case of azobenzene chromophore containing polymers trans-cis photoisomerization is significant for photoorientation; 6. Crosslinked polymer films oriented by irradiation of main chain polymers with linearly polarized light possess an increased stability in comparison with non- crosslinked polymer films; 7. The polymers investigated in this work are main chain polymers, which contain the distyrylbenzene chromophore and a flexible aliphatic chain; 8. Trans-cis photoisomerization and 2+2 photocycloaddition can competitively occur during irradiation of the photochromic main chain polymers even in the glassy state; 9. The new fluorine containing photoactive polymers 1 and 2, which contain the distyrylbenzene chromophore within the main chain, have been investigated in comparison with the photoactive polymer 3, which possesses a similar chemical structure; and 10. The capability of the photoalignment layer in order to align a liquid crystal was investigated as a function of both surface topography and photoinduced dichroism of the photoalignment layer.