Study of Hydrogen-Bonded Banana-Shaped LC Triads and Main-Chain Polymers Containing Siloxane Linking Groups and Chiral Flexible Chains

• Main Author: 黃冠穎
• Other Authors: 林宏洲
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/35321657127908973706

碩士 === 國立交通大學 === 材料科學與工程學系 === 101 === In this study, five types of diacids containing two or three siloxane linking groups in center and various aromatic rings at both terminals were synthesized. These diacids were mixed with pyridine and bipyridine, with or without chiral center, to form H-bonded banana-shaped triads and main-chain polymers. The chemical structures were characterized by H1-NMR and EA, and the liquid crystalline(LC) phases and mesomorphic behavior of all these compounds were investigated using POM, DSC, XRD, and Electro-optical measurement.. It was found that two siloxane linking groups with short mesogenic group could lose its LC phase, while three siloxane linking groups with the same mesogenic group could obtain LC phase. Furthermore, increasing the rigidity of aromatic rings could increase LC range. Adding the chiral center, allows non-LC phase products to turn into LC phase, slightly decreases the LC temperature, and broadens the LC temperature range. Due to the H-bonded molecular design, all the phases we obtained are smectic C (SmC).