Browsing by Author "Jeng, RJ"

Now showing 1 - 2 of 2

Ferroelectric liquid crystalline polymers based on mesogens with halogen-containing terminal groups
(2003-01-01)
Sha, YA
;
Hsiue, GH
;
Chiu, CH
;
Jeng, RJ
;
Tai, HC
A new series of halogen-containing side chain ferroelectric liquid crystal polymers was synthesized. Mesophases were characterized by differential scanning calorimetry, polarizing optical microscopy. X-ray diffraction and molecular simulation. The behaviour of the liquid crystalline phase was investigated with variation of chiral centres. spacer units and grafted ratios. It was found that the thermal stability and temperature range of the chiral smectic C phase decreased with increasing length of the oligo-oxyethylene spacer. and decreasing mesogenic group content. The bulky substituent attached to the chiral centre reduces molecular packing in smectic liquid crystal phases, which disturbs the orientation of the side chain liquid crystal polymer. Furthermore, the influence of molecular structure on electro-optical properties of FLCPs has been studied by broad band dielectric spectroscopy (from 0.1 to 1 x 10(6) Hz).
Synthesis and characterization of halogen-containing ferroelectric liquid crystals and side chain liquid crystalline polymers
(2001-03-01)
Hsiue, GH
;
Sha, YA
;
Hsieh, SJ
;
Jeng, RJ
;
Kuo, WJ
A new series of ferroelectric liquid crystals and side chain liquid crystalline polymers based on halogen-containing chiral centres has been synthesized. Chemical structures were analysed by NMR. Liquid crystal phases were characterized by differential scanning calorimetry, optical polarizing microscopy, and X-ray diffractometry. The behaviour of the liquid crystalline phases was investigated as a function of spacer units and differing terminal asymmetric moieties. It was found that phase transition temperatures decreased with increasing length of the oligooxyethylene spacer unit. Differing terminal asymmetric moieties led to differing mesophase phenomena. Furthermore, a wide temperature range (including room temperature) of a chiral smectic C phase was achieved.