Terminal Effect of the Semi-fluorocarbon Chain on the Liquid Crystalline Behaviors of Some Compounds |
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| Authors: | Xiaoqing Wu Yongmin Guo Yi Li Baozong Li |
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| Institution: | Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P.R. China |
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| Abstract: | Two series of chiral compounds with semi-perfluorocarbon chains and alkoxy ones, nBP4F and nBP6F, are synthesized. Enantiotropic SmA phase is identified in all of these compounds. When the alkoxy chain length is short, enantiotropic SmB is also identified. When the alkoxy chain length is longer than 6 carbons, enantiotropic SmC* phase is formed. Their clearing points increase with increasing the perfluorocarbon chain length. Comparison of compounds with -CF3, -CHF2 and -CF2Cl groups at the terminals of the fluorocarbon chains, the clearing point sequence is -CHF2 < -CF2Cl < -CF3; and the melting point sequence is -CF3 < -CHF2 < -CF2Cl. Therefore, the compounds with semi-perfluorocarbon chains show the widest liquid crystalline temperature range. Moreover, the SmC* phase of the compounds with -CF3 at the terminals shows the highest thermostability. |
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| Keywords: | semi-perfluorocarbon chain liquid crystal terminal modification chirality |
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