Study of Polymer Dopant Effects on Covalent-Bonded and H-Bonded Bent-Core Liquid Crystals

• Main Author: 湯捷茵
• Other Authors: 林宏洲
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/75759582099352980416

碩士 === 國立交通大學 === 材料科學與工程系所 === 96 === In order to improve the properties of H-bonded bent core mesogens, there is two series for our research, one is mixtures of single hydrogen bonded banana-shaped polymer doped with covalent bonded banana-shaped liquid crystals；another is mixtures of single hydrogen bonded banana-shaped compound doped with covalent bonded banana-shaped polymer. The phases were demonstrated by polarized light optical microscopy (POM), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), and electro-optical properties based on dielectric response as well as measurements of polarization reversal current. The temperature range of the B2 phase of mixtures was extended from several degrees to about fifteen to thirty degrees due to the contribution of covalent bonded LCs；for both series, as polymer is less than 20 wt％, the spontaneous polarization (PS) shows up；moreover, the spontaneous polarization (PS) of single H-bonded LCs was increased from about 250 nC/cm2 to 500 nC/cm2 with the increasing of the percentage of the covalent bonded mesogens linearly. The relationships between Ps value and applied voltage were also studied. Saturated applied voltage can be reduced by doping H-bonded mesogens in covalent bonded LCs.