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URN etd-0706105-162158 Statistics This thesis had been viewed 2238 times. Download 969 times. Author Kuan-Ting Chen Author's Email Address No Public. Department Chemical Engineering Year 2004 Semester 2 Degree Master Type of Document Master's Thesis Language English Page Count 85 Title Synthesis and Properties of Thioester Liquid Crystals Derived from (S) - Lactic Acid Keyword thioester liquid crystals ferroelectric liquid crystals ferroelectric liquid crystals liquid crystals thioester Abstract The primary research was an attempt to study the correlation between structure and property in the chiral liquid crystal materials. Three homologous series of chiral materials derived from (S)-lactic acid were successfully synthesized and investigated the relationship between molecular structures and the mesomorphic properties relationship. The target compounds were modified independently by (i) the length of achiral aliphatic chain ’m’ (ii) the lateral substitution group in the core and (ii) the structure of chiral aliphatic chain.
The results show that chiral liquid crystal, compounds of I-6 (m=8~12) exhibit the mesophases sequence BPII?N*?SmC*, compounds of II-6 (m=8~12) exhibit the mesophases sequence N*?TGBA*?SmA* and compounds of III-6 (m=8~12) exhibit the mesophases sequence N*?TGBA*?SmA*?SmC*. With the increasing achiral aliphatic chain lengths ’m’, the clearing point and the melt point decrease, the temperature range of the N* phase decreases but the temperature range of the SmC* phase increases. The materials with lateral 3-methyl substitution in the phenyl ring of core could depress the formation of the SmC* phase. The structure of chiral aliphatic chain effects the formation of the mesophase, transition temperature, melting point and clearing point.
The electro-optical responses of chiral materials in the SmC* phase display a typical ferroelectric switching behaviour. The maximum Ps values I-6 (m=10~12) are about 91~95nC/cm2 and the maximum tilt angles are about 34~37°. The maximum Ps values III-6 (m=10~12) are about 112~120nC/cm2 and the maximum tilt angles are about 34~35°.
Advisor Committee Shune-Long Wu - advisor
Chain-Shu Hsu - co-chair
Hong-Cheu Lin - co-chair
Files Date of Defense 2005-07-01 Date of Submission 2005-07-06