Tailoring the Liquid Crystalline Property via Controlling the Generation of Dendronized Polymers Containing Azobenzene Mesogen

The first- and second-generation dendronized polymers containing azobenzene mesogen were designed and successfully synthesized via free radical polymerization. The chemical structures of the monomers were confirmed by elemental analysis, H-1 NMR, and C-13 NMR. The molecular characterizations of the polymers were performed with H-1 NMR and gel permeation chromatography. The phase structures and transition behaviors were studied using differential scanning calorimetry, polarized light microscopy, and small-angle X-ray scatter experiments. The experiment results revealed that the first-generation dendronized polymer exhibited liquid crystalline behavior of the conventional side-chain liquid crystalline polymer with azobenzene mesogen, that is, the polymer exhibited smectic phase structure at lower temperature and nematic phase structure at higher temperature. However, the second-generation dendronized polymers exhibited more versatile intriguing liquid crystalline structures, namely smectic phase structure at lower temperature and columnar nematic phase structure at higher temperature, and moreover, the phase structure still remained before the decomposition temperature. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1149-1159, 2010