Synthesis and Properties of Thioester Liquid Crystals Derived from (S) - Lactic Acid

• Main Authors: Kuan-Ting Chen, 陳冠廷
• Other Authors: Shune-Long Wu
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/27955632798043594440

碩士 === 大同大學 === 化學工程學系(所) === 93 === 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°.