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 |
顯示於類別: | 期刊論文 |