標題: Synthesis and characterization of achiral banana-shaped liquid crystalline molecules containing bisnaphthyl moieties
作者: Yang, Po-Jen
Lin, Hong-Cheu
材料科學與工程學系
Department of Materials Science and Engineering
公開日期: 1-May-2006
摘要: Three analogous series of symmetric banana-shaped liquid crystalline molecules containing bisnaphthyl units were synthesized and characterized. The effects of linking groups (on the side wings) and lateral meta-fluoro substitutions (on the middle outer rings) on the mesogenic properties were examined. The type of mesophase depends on the lengths of terminal alkoxy chains. Thus, achiral molecules with shorter flexible chains (n = 8) exhibit a rectangular columnar (B-1) phase, while analogous derivatives with longer flexible chains (n = 12) display the B-2 phase. All lateral meta-fluoro substituted analogues (series II) possess the lowest isotropization temperatures and the narrowest mesophasic ranges of the B-1 and B-2 phases. The B-1 and B-2 phases were confirmed by X-ray diffraction, polarizing optical microscopy (POM) and electro-optical (EO) switching experiments. An electric field-induced transition from an antiferroelectric (tristable) state to a ferroelectric (bistable) state was observed in the EO measurements. Spontaneous polarization (by switching current response), tilt angle of chiral domains (by POM), and transmittance -voltage measurements of the B-2 phase in related compounds have been surveyed in this study.
URI: http://dx.doi.org/10.1080/02678290600633394
http://hdl.handle.net/11536/12340
ISSN: 0267-8292
DOI: 10.1080/02678290600633394
期刊: LIQUID CRYSTALS
Volume: 33
Issue: 5
起始頁: 587
結束頁: 603
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