Abstract
It is known that liquid crystalline molecules can exist with guest molecules in the liquid crystalline state. If the structure of guest molecule is greatly different from that of the host molecule, a small amount of guest molecule disturbs liquid crystalline structure and inhibits the formation of the liquid crystal in the system. Therefore, the formation of liquid crystal can be controlled by structural change of the guest molecules. The photoisomerization of azobenzene molecule was utilized for this structural change. In this study, liquid crystalline molecules of carbonate and azomethine were used and methoxyazobenzene was used as the photoisomerizable molecule. The liquid crystal formation was measured by DSC and polarizing optical microscope. The phase transition temperature of the liquid crystal mixture after the structural change of the photoisomerizable molecule was also meastiied. It was found that the liquid crystal formation of the mixed system could be controlled by the 1.5 h irradiation of 365 nm light at the concentrations between about 5 to 30 mol% of methoxyazobenzene. When the film of this mixture was irradiated by 365 nm light under a masking plate, the masked image was clearly recorded by the isomerization of methoxyazobenzene. The image was observed under cross polarizers of polarizing microscope at liquid crystal temperature. However, this image was not observed at lower temperature because of the crystallization. When this mixture was raised at liquid crystal temperature, the masked image appeared again. Though the memory of the irradiation was preserved, the image became looser because of the diffusion and the reverse photo- or thermal-isomerization.
