首页 | 本学科首页   官方微博 | 高级检索  
     


Structure property and mesomorphic behaviour of S-shaped liquid crystal oligomers possessing two azobenzene moieties
Authors:Faridah Osman  Akihiko Nagashima  Masato M. Ito
Affiliation:1. Liquid Crystal Research Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia;2. Faculty of Science &3. Engineering, Soka University, Hachioji, Tokyo, Japan
Abstract:
A new series of symmetrical S-shaped oligomers 4,4?-bis(ω-2-(ω-[(bromophenyl)diazenyl]-alkoxy)phenoxy)hexylbiphenyl consisting of two different spacers (inner -(CH2)6- and outer -(CH2)n-) have been synthesised. Their physical, thermal and texture observation over various transition temperatures are reported. The outer spacers for these compounds vary from n = 4 to n = 9. The oligomers with even number of members exhibit monotropic phase in which the compound with n = 4 shows nematic (N) phase whilst those with members n = 6 and 8 exhibit N and smectic A (SmA) phases. However, the homologs with odd number of members display enantiotropic phase in which the compound with n = 5 exhibits N and smectic phases whereas the members with n = 7 and 9 are predominantly smectogenic. The temperature range of N phase for even-numbered member decreased with elongation of the outer spacer. The smectic phase stability among the members in the present series increases when the outer spacer n is increased from 5 to 8.
Keywords:Symmetrical S-shaped  mesomorphic behaviour  monotropic  enantiotropic  outer spacer
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号