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URN etd-0702104-143649 Statistics This thesis had been viewed 2214 times. Download 1065 times. Author Yen-chih Wu Author's Email Address No Public. Department Chemical Engineering Year 2003 Semester 2 Degree Master Type of Document Master's Thesis Language English Page Count 71 Title SYNTHESIS AND ELECTRO-OPTICAL PROPERTIES OF NEW CHIRAL LIQUID CRYSTAL DERIVED FROM (R)-2-(4-HYDROXYPHENOXY)PROPIONIC ACID Keyword propionic acid propionic acid Abstract The primary of this research work was an attempt to elucidate the structure-property correlation in the chiral smectic liquid crystal. A homologous series of chiral materials derived from (R)-(+)-2-(4-hydroxyphenoxy)propanoic acid, has been successfully synthesized and the structures-property relationship investigated in the chiral liquid crystal system. The target compounds were modified independently by the (i) nonchiral peripheral chain length, (ii) the chiral tailed ether alkyl chain length (iii) the linking groups; where the chiral group is connected to the rigid core by ether group.
Chiral materials of three series Ⅰ(m=8~12, n=1), Ⅱ(m=8~12, n=3), and Ⅲ(m=8~12, n=4) displayed enantiotropic mesophases of the SmA* and SmC* phases and most of them have SmX* phase. In compounds Ⅲ(m=8~12, n=4) the temperature range of the mesophase decrease as the nonchiral chain length was increased. It means that the clearing point decreased and the crystal point increased. When the chiral tailed ether alkyl chain length ‘n’ was increased, the temperature range of the SmC* phase and SmX* were decreased.
The electro-optical response in the series of chiral materials in the SmC* phase displayed typical ferroelectric hysteresis loop or hysteresis-free, V-shaped switch property upon various applied frequencies and temperatures. The maximum Ps values of Ⅰ(m=9~11, n=1), Ⅱ(m=9~11, n=3), and Ⅲ(m=8~10, n=4) vary from 34.20~124.32 nC/cm2. Ps value decreases with increasing of the chiral tailed chain length ’n’. The maximum tilt angles of Ⅰ(m=9~11, n=1), Ⅱ(m=9~11, n=3), and Ⅲ(m=8~10, n=4) were in the range of 14.5o~31.5o. There is also a decreasing tendency of tilt angle as increasing chiral chain length.
In conclusion, the results indicated that the chiral tailed ether alkyl chain materials derived from (R)-(+)-2-(4-hydroxyphenoxy)propanoic acid are favorable for the formation of the ferroelectric phase. V-shaped switching behavior achieved in the SmC* phase of the three series of chiral compounds.
Advisor Committee Shune-long Wu - advisor
Chin-tsou Kuo - co-chair
Jiunn-yih Lee - co-chair
Liang-jye Yu - co-chair
Files Date of Defense 2004-06-09 Date of Submission 2004-07-02