Liquid crystal comb polymer with polar mesogenic and aliphatic side groups I. Preparation and structural properties |
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Authors: | B Gallot P Allia P Taverna L Trossi C Cucinelli S Ponti |
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Institution: | Center of Opto-electronic Materials, Xi’an Modern Chemistry Research Institute, Xi’an, PR China |
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Abstract: | A liquid crystal comb polymer of potential interest for electro-optical applications has been synthesized and characterized. The polymer has a polyacrylamide main chain and two different types of side group, built up of 4'-undecanoyloxy-4-cyanobiphenyl groups (68 mol %) and of shorter aliphatic groups (32 mol %). The two types of side group occur randomly along the polymer's main chain. The preparation steps and the liquid crystalline structure of the resulting copolymer are compared with those of a homopolymer whose side groups (built up of 4'-undecanoyloxy-4-cyanobiphenyl groups) are all identical. X-ray diffraction shows that the polymers display different mesophases over different temperature ranges. However, the homopolymer exhibits two smectic phases (SmC2 and SmA2), while the new copolymer exhibits a SmC2 phase and a nematic mesophase at higher temperature. The mesophase thermal stability of the copolymer is significantly lower than that of the homopolymer. |
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Keywords: | fluorinated liquid crystal tolane synthesis mesophase birefringence dielectric anisotropy rotational viscosity |
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