Preparation and properties of highly birefringent liquid crystalline materials: styrene monomers with acetylenes,naphthyl, and isothiocyanate groups |
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Authors: | Lan-Ying Zhang Xiao-Lin Guan Zhen-Lin Zhang Xiao-Fang Chen |
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Institution: | 1. Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education , College of Chemistry and Molecular Engineering, Peking University , Beijing, 100871, China;2. Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education , College of Chemistry and Molecular Engineering, Peking University , Beijing, 100871, China;3. College of Chemistry and Environmental Engineering, Chongqing Three Gorges University , Chongqing, 404000, China |
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Abstract: | Two new series of styrene monomers with different alkyl chain length were successfully synthesised. The chemical structures of synthetic intermediates and monomers were confirmed by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, mass spectrometry and elemental analysis. Their thermal stability, transition temperatures and phase sequences were investigated by polarised light microscopy, thermogravimetric analysis, differential scanning calorimetry and one-dimensional wide-angle X-ray diffraction. The birefringent and photoelectric properties, UV–vis and fluorescence spectroscopy were also measured using Abbe refractometer and fluorescent apparatus. The results indicated that all the monomers exhibited a liquid crystalline phase at higher temperature, high birefringence values between 0.4 and 0.7, and good photoluminescence properties. Optical anisotropy of homologous molecules was reduced with the increase of alkyl chain length due to the decrease of molecular polarisation. Moreover, a significant effect of the chemical structure on the photoluminescence properties was also found and discussed according to the length of π-conjugation. |
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Keywords: | liquid crystal birefringent photoelectric properties mesogen-jacketed liquid crystalline polymers |
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