標題: Liquid crystal dimers containing Cholesteryl and Triazole-containing mesogenic units
作者: Al-shargabi, Arwa
Yeap, Guan-Yeow
Mahmood, Wan Ahmad Kamil
Han, Chun-Chieh
Lin, Hong-Cheu
Ito, Masato M.
材料科學與工程學系
Department of Materials Science and Engineering
關鍵字: Hybrid core;click chemistry;TGB phase;Triazole;Cholesterol;Chiral
公開日期: 1-一月-1970
摘要: New liquid crystals categorised as cholesteryl dimers have been successfully synthesised through the reaction between cholesteryl 4-(prop-2-ynyloxy)benzoate moieties with n-azido(cholesteryloxy-carbonyl)alkane. All the dimers display enantiotropic mesophases. Whilst the odd-numbered dimers exhibit chiral nematic (N*), twisted grain boundary (TGB) and chiral smectic C (SmC*) phases, the even-numbered members from the same series show chiral smectic A and C. A detailed inspection on mesophase reveals that the chiral centres and the bent conformation of the odd-numbered members are essential for the induction of TGB phase. However, upon decreasing the temperature, the ratio of the transition temperatures (TSmC*-SmA*/TSmA*-I) is found to be 0.95, which indicate the second order transition according to the McMillan's molecular theory. In addition, the X-ray diffraction study supports the presence of the smectic A phase on the even members rather than the N* by the appearance of the Bragg diffraction peaks at 190 degrees C. A comparison study with the other analogues in which the cholesterol entity is substituted by azobenzene or biphenyl tails has been carried out to assess the relationship between the molecular structure and mesomorphic behaviour. [GRAPHICS] .
URI: http://dx.doi.org/10.1080/02678292.2019.1641637
http://hdl.handle.net/11536/152668
ISSN: 0267-8292
DOI: 10.1080/02678292.2019.1641637
期刊: LIQUID CRYSTALS
起始頁: 0
結束頁: 0
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