Synthesis And Characterization Of Azobenzene Liquid Crystal Materials Containing Chiral Carbon

As well-known azobenzene undergoes photoinduced and thermal as a kind of photosensitive chromorphore. By attaching with azobenzene group, the polymer molecules can be helped to be more ordered. Because of quite low activation energy, the compounds containing azobenzene group have been widely considered for potential application in the field of photoswitching and optical storage.Two kinds of compound were synthesized in this paper.(â… ) Poly(L-lactic acid)(PLLA) of two armed containing azobenzene group;(â…¡) Bent-core liquid crystal materials containing azobenzene and chiral carbon.(â… ) Poly(L-lactic acid)(PLLA) of two armed containing azobenzene groupPoly L-Lactide can form chiral helical structure with thermodynamic and kinetic stability because of many chiral carbon atoms in the main chain, Chiral helix materials usually have large optical rotatory power and caught much attention for optical elements and optical switching devices. But the high crystallinity of Poly L-Lactide reduces its ability of self-assembly, so it is diffcult to use Poly L-Lactide to prepare excellent optical devices with excellent molecular orientation.Poly(L-lactic acid)(PLLA) containing azobenzene group were synthesized for the evaluation of their self-assembly properties being improved and with reduced crystallinity, and the novel polymers may have great potential application to be used as good polymer candidate materials for optical field.HO3OPNPO3OH and HO6OPNPO6OH containing active hydroxyl were synthesized then a series of oligo polylactic acid containing azobenzene with different repeat units and narrow polydispersity were obtained.Their molecular weights were well controlled by the feed ratio as characterized by GPC and1H NMR Spectrometry and agreed well with theoretical values. The thermal properties and liquid crystal phases were investigated by DSC, POM and XRD measurements. Cis-trans photoisomerization behavior of the polymers in the solutions were studied with UV-vis Spectrometry. By the Circular Dichroism Spectroscopy (CD) characterization of the solutions of the polymer, the PLLA segments show huge optical rotation power in helical structure.(â…¡) Bent-core liquid crystal containing azobenzene and chiral carbon.p-nOPCOOPCOOH was synthesized by using HOPCHO, HO3*OPNPO3*OH was prepared from4-aminophenol. Para-n(n=6,8,12)were synthesized according to esterify reaction by using p-nOPCOOPCOOH and HO3*OPNPO3*OH as reagents.The chemical structures of the compounds were confirmed by1H NMR. The thermal properties and liquid crystal phases were investigated by DSC, POM. Para-10and Para-12form thermotropic liquid crystals as expected, which may be used for novel material in the field of photoswitching and optical storage.