ABSTRACT
Figure 4.2 gives one example of one azobenzene compound, 4-ethoxy-4′-(6-hydroxy hexyloxy) azobenzene, showing an LC phase in 104-129°C upon cooling. Its colorful four-arm texture was clearly observed with a polarizing optical microscope (POM) at 110°C. At the LC temperature, a dark image is easily induced in the UV-irradiated area due to the loss of birefringence in its isotropic phase (a cis-azobenzene rich state). The LC phase can be restored upon irradiation with visible light or thermal treatment because of the completely reversible cis-to-trans isomerization of the azobenzene LMWLC compound.
