科研之友
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摘要
A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)phenylazo]nitrobenzene (M-NO2). A terminal Si-Cl functional carbosilane dendrimer based on pentaerythritol was used as dendritic scaffold and subsequently functionalized with the aforementioned groups. Investigation of the liquid crystalline properties of the mesogen-functionalized dendrimer PCSi-1G-NO2 by polarizing optical microscopy, DSC, and X-ray diffraction showed that it exhibits smectic E (S-E) phase, different from the corresponding mesogenic unit, which shows nematic phase. Furthermore, the temperatures of both the melting point and the clearing point of the mesogen-functionalized dendrimer decrease, and the temperature region of the SE phase is wider than that of the nematic phase.
