| A special liquid crystal complex system was prepared through doping the chiral and achiral azobenzene liquid crystal compound(Azo-CC, Azo-ACC) into the matrix liquid crystal 5CB. Azo-CC and Azo-ACC are designed and synthesized in this paper. And a dendritic gelator(POSS-G1-BOC) was added into the complex system innovatively to prepare liquid crystal physical gel. The thermal and liquid crystalline properties of the azobenzene compounds and the complex system were investigated, separately. Besides, the gelling property and photo-responsive performance of the liquid crystal physical gel with different azobenzene light response agents were studied. Analyzing of the liquid crystal physical gel properties showed its application of potential value in the field of light scattering. The main content of this paper includes the following sections:Doping the synthesized of chiral and achiral azobenzene liquid crystal compound(Azo-CC, Azo-ACC) into the matrix liquid crystal 5CB to prepare the complex system. After investigating thermal and liquid crystalline properties of the azobenzene compounds and the complex system, the result showed that the introduction of chiral group not only made the liquid crystal molecular reoriented but also could change the whole nematic host liquid crystal to the helical-twisted kind.Doping 4, 4-2 ethoxy azobenzene liquid crystal compounds into the matrix liquid crystal 5CB, and adding POSS nuclear dendritic gelator(POSS-G1-BOC) into the former complex system to prepare liquid crystal physical gel. By studying the behavior and strength of the gel and the surface morphology of the dry gel with different azobenzene light response agents, the result indicated that the different light response agents had little influence on the gelling property of the liquid crystal gel. With 0.1wt% concentration of the gelator, the complex system could form a gel. And when the concentration of the gelator was only 0.5wt%, the sol-gel temperature of the system could reach 110 oC, which showed its good thermal stability. It concluded that the liquid crystal physical gel had a good property of deformation resistance from the result of strain sweep. That meant it could be applied as the liquid crystal material with the independent shape. The SEM figure of the dry gel surface showed that the liquid crystal molecules were separated into numerous small domain regions by the network of the gel due to its unique “loofah-like” structure. That provided the possibility of the liquid crystal physical gel had a faster response performance.The research of the photo-responsive liquid crystal physical gel with different response agents demonstrated that chiral liquid crystal physical gel had a faster optical response performance and was capable of a shorter time to reach an equilibrium state of the light transmittance compared to the achiral system. Meanwhile, the good fatigue resistance of the liquid crystal physical gel could realize the reuse of the materials.Based on the good gelling property and fast photo-responsive performance, the liquid crystal physical gel could be changed from the scattered state to the transmission state under the condition of the UV irradiation and heating. The features of the materials made them can be applied to the areas of light scattering display. In order to improve the image contrast, an oily fluorescent dye was doped into the liquid crystal physical gel to prepare the fluorescent light scattering display and the fluorescent properties of the system also were characterized. |
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